建設(shè)網(wǎng)站那些公司靠譜/百度網(wǎng)盟推廣
文章目錄
- 三. Netty 進階
- 1. 粘包與半包
- 1.1 ==粘包==現(xiàn)象
- 服務(wù)端代碼
- 客戶端代碼
- 1.2 ==半包==現(xiàn)象
- 服務(wù)端代碼
- 客戶端代碼
- 1.3 現(xiàn)象分析
- 粘包
- 半包
- 緣由
- 滑動窗口
- MSS 限制
- Nagle 算法
- 1.4 解決方案
- 方法1，短鏈接
- 方法2，固定長度
- 方法3，固定分隔符
- 方法4，預(yù)設(shè)長度
- 2. 協(xié)議設(shè)計與解析
- 2.1 為什么需要協(xié)議？
- 2.2 redis 協(xié)議舉例
- 2.3 http 協(xié)議舉例
- 2.4 自定義協(xié)議要素
- 編解碼器
- MessageCodec
- TestMessageCodec
- 輸出
- 💡 什么時候可以加 @Sharable
- 3. 聊天室案例
- 3.1 聊天室業(yè)務(wù)介紹
- 3.2 聊天室業(yè)務(wù)-登錄
- 3.3 聊天室業(yè)務(wù)-單聊
- 3.4 聊天室業(yè)務(wù)-群聊
- 3.5 聊天室業(yè)務(wù)-退出
- 3.6 聊天室業(yè)務(wù)-空閑檢測
- 連接假死
三. Netty 進階
1. 粘包與半包
1.1 粘包現(xiàn)象
服務(wù)端代碼
@Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss = new NioEventLoopGroup(1);NioEventLoopGroup worker = new NioEventLoopGroup();try {ServerBootstrap serverBootstrap = new ServerBootstrap();serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug("connected {}", ctx.channel());super.channelActive(ctx);}@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {log.debug("disconnect {}", ctx.channel());super.channelInactive(ctx);}});}});ChannelFuture channelFuture = serverBootstrap.bind(8080);log.debug("{} binding...", channelFuture.channel());channelFuture.sync();log.debug("{} bound...", channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("server error", e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug("stoped");}}public static void main(String[] args) {new HelloWorldServer().start();}
}
客戶端代碼
客戶端代碼希望發(fā)送 10 個消息，每個消息是 16 字節(jié)
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import lombok.extern.slf4j.Slf4j;@Slf4j
public class HelloWorldClient {public static void main(String[] args) {NioEventLoopGroup worker = new NioEventLoopGroup();try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {log.debug("connected...");ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 會在連接 channel 建立成功之后，會觸發(fā) active事件@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug("sending...");for (int i = 0; i < 10; i++) {ByteBuf buffer = ctx.alloc().buffer();buffer.writeBytes(new byte[]{0, 1, 2, 3, 4,5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15});ctx.writeAndFlush(buffer);}}});}});ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("client error", e);} finally {worker.shutdownGracefully();}}
}服務(wù)器端的某次輸出，可以看到一次就接收了 160 個字節(jié)，而非分 10 次接收。而我們客戶端是發(fā)了10次，每次16字節(jié)，這就是粘包現(xiàn)象。
// 客戶端輸出
/*
11:57:47 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - connetted...
11:57:47 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - sending...
*/// 服務(wù)器端輸出
/*
11:57:08 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0x6e5efdad] binding...
11:57:08 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0x6e5efdad, L:/0:0:0:0:0:0:0:0:8080] bound...
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] REGISTERED
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] ACTIVE
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] c.z.a.HelloWorldServer - connected [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248]
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] READ: 160B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000010| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000020| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000030| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000040| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000050| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000060| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000070| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000080| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000090| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
+--------+-------------------------------------------------+----------------+
11:57:47 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0xfaf43bd5, L:/127.0.0.1:8080 - R:/127.0.0.1:65248] READ COMPLETE*/
1.2 半包現(xiàn)象
服務(wù)端代碼
只添加serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);這一行代碼
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;@Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss = new NioEventLoopGroup(1);NioEventLoopGroup worker = new NioEventLoopGroup();try {ServerBootstrap serverBootstrap = new ServerBootstrap();// 為現(xiàn)象明顯，服務(wù)端修改一下接收緩沖區(qū)，其它代碼不變// （調(diào)整系統(tǒng)的接收緩沖區(qū)-即滑動窗口）serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug("connected {}", ctx.channel());super.channelActive(ctx);}@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {log.debug("disconnect {}", ctx.channel());super.channelInactive(ctx);}});}});ChannelFuture channelFuture = serverBootstrap.bind(8080);log.debug("{} binding...", channelFuture.channel());channelFuture.sync();log.debug("{} bound...", channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("server error", e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug("stoped");}}public static void main(String[] args) {new HelloWorldServer().start();}
}
客戶端代碼
客戶端沒有任何代碼變動
@Slf4j
public class HelloWorldClient {public static void main(String[] args) {NioEventLoopGroup worker = new NioEventLoopGroup();try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {log.debug("connected...");ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 會在連接 channel 建立成功之后，會觸發(fā) active事件@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug("sending...");for (int i = 0; i < 10; i++) {ByteBuf buffer = ctx.alloc().buffer();buffer.writeBytes(new byte[]{0, 1, 2, 3, 4,5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15});ctx.writeAndFlush(buffer);}}});}});ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("client error", e);} finally {worker.shutdownGracefully();}}
}
輸出如下，可以看到客戶端發(fā)了10次，每次16字節(jié)的消息，但是服務(wù)端分幾次接受了36B、50B、50B、24B加起來共160字節(jié)。
（只要是使用TCP協(xié)議，那就會出現(xiàn)粘包和半包問題）
// 客戶端輸出
/*
12:10:42 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - connected...
12:10:42 [DEBUG] [nioEventLoopGroup-2-1] c.z.a.HelloWorldClient - sending...
*/// 服務(wù)端輸出
/*
12:10:32 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xdafb9db3] binding...
12:10:32 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xdafb9db3, L:/0:0:0:0:0:0:0:0:8080] bound...
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] REGISTERED
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] ACTIVE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] c.z.a.HelloWorldServer - connected [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450]
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 36B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000010| 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
|00000020| 00 01 02 03 |.... |
+--------+-------------------------------------------------+----------------+
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 50B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 |................|
|00000010| 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 |................|
|00000020| 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 |................|
|00000030| 04 05 |.. |
+--------+-------------------------------------------------+----------------+
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 50B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 |................|
|00000010| 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 |................|
|00000020| 06 07 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 |................|
|00000030| 06 07 |.. |
+--------+-------------------------------------------------+----------------+
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ: 24B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 08 09 0a 0b 0c 0d 0e 0f 00 01 02 03 04 05 06 07 |................|
|00000010| 08 09 0a 0b 0c 0d 0e 0f |........ |
+--------+-------------------------------------------------+----------------+
12:10:42 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:12:26 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] READ COMPLETE
12:12:26 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x07aed482, L:/127.0.0.1:8080 - R:/127.0.0.1:65450] EXCEPTION: java.io.IOException: 遠(yuǎn)程主機強迫關(guān)閉了一個現(xiàn)有的連接。*/
注意
serverBootstrap.option(ChannelOption.SO_RCVBUF, 10) 影響的底層接收緩沖區(qū)（即滑動窗口）大小，僅決定了 netty 讀取的最小單位，netty 實際每次讀取的一般是它的整數(shù)倍
1.3 現(xiàn)象分析
粘包
-
現(xiàn)象，發(fā)送 abc def，接收 abcdef
-
原因
- 應(yīng)用層（應(yīng)用層面）：接收方 ByteBuf 設(shè)置太大（Netty 默認(rèn) 1024）
- 滑動窗口（TCP層面）：假設(shè)發(fā)送方 256 bytes 表示一個完整報文，但由于接收方處理不及時且窗口大小足夠大，這 256 bytes 字節(jié)就會緩沖在接收方的滑動窗口中，當(dāng)滑動窗口中緩沖了多個報文就會粘包
- Nagle 算法（TCP層面）：會造成粘包（因為報文頭也占據(jù)一定的大小，如果攜帶的實際數(shù)據(jù)較小，那顯然不劃算，因此會攢夠了一批量數(shù)據(jù)，然后發(fā)送過去，因此也會造成粘包）
半包
- 現(xiàn)象，發(fā)送 abcdef，接收 abc def
- 原因
- 應(yīng)用層（應(yīng)用層面）：接收方 ByteBuf 小于實際發(fā)送數(shù)據(jù)量
- 滑動窗口（TCP層面）：假設(shè)接收方的窗口只剩了 128 bytes，發(fā)送方的報文大小是 256 bytes，這時放不下了，只能先發(fā)送前 128 bytes，等待 ack 后才能發(fā)送剩余部分，這就造成了半包
- MSS 限制（鏈路層面）：當(dāng)發(fā)送的數(shù)據(jù)超過 MSS 限制后，會將數(shù)據(jù)切分發(fā)送，就會造成半包
本質(zhì)是因為 TCP 是流式協(xié)議，消息無邊界
緣由
滑動窗口
TCP 以一個段（segment）為單位，每發(fā)送一個段就需要進行一次確認(rèn)應(yīng)答（ack）處理，但如果這么做，缺點是包的往返時間越長性能就越差（因為tcp協(xié)議是可靠的傳輸協(xié)議，因此需要保證1次請求1次應(yīng)答，但是如果等到上一次請求得到應(yīng)答，再發(fā)送下一次請求，那效率顯然就很低，因此下面引入了滑動窗口來解決這個問題）
[外鏈圖片轉(zhuǎn)存失敗,源站可能有防盜鏈機制,建議將圖片保存下來直接上傳(img-leJ1X8om-1690552927974)(assets/0049.png)]
為了解決此問題，引入了窗口概念，窗口大小即決定了無需等待應(yīng)答而可以繼續(xù)發(fā)送的數(shù)據(jù)最大值
[外鏈圖片轉(zhuǎn)存失敗,源站可能有防盜鏈機制,建議將圖片保存下來直接上傳(img-c4Pwo8wB-1690552927976)(assets/0051.png)]
窗口實際就起到一個緩沖區(qū)的作用，同時也能起到流量控制的作用
- 圖中深色的部分即要發(fā)送的數(shù)據(jù)，高亮的部分即窗口
窗口內(nèi)的數(shù)據(jù)才允許被發(fā)送，當(dāng)應(yīng)答未到達(dá)前，窗口必須停止滑動
如果 1001~2000 這個段的數(shù)據(jù) ack 回來了，窗口就可以向前滑動
接收方也會維護一個窗口，只有落在窗口內(nèi)的數(shù)據(jù)才能允許接收
MSS 限制
鏈路層對一次能夠發(fā)送的最大數(shù)據(jù)有限制，這個限制稱之為 MTU（maximum transmission unit），不同的鏈路設(shè)備的 MTU 值也有所不同，例如
以太網(wǎng)的 MTU 是 1500
FDDI（光纖分布式數(shù)據(jù)接口）的 MTU 是 4352
本地回環(huán)地址的 MTU 是 65535 - 本地測試不走網(wǎng)卡
MSS 是最大段長度（maximum segment size），它是 MTU 刨去 tcp 頭和 ip 頭后剩余能夠作為數(shù)據(jù)傳輸?shù)淖止?jié)數(shù)
ipv4 tcp 頭占用 20 bytes，ip 頭占用 20 bytes，因此以太網(wǎng) MSS 的值為 1500 - 40 = 1460
TCP 在傳遞大量數(shù)據(jù)時，會按照 MSS 大小將數(shù)據(jù)進行分割發(fā)送
MSS 的值在三次握手時通知對方自己 MSS 的值，然后在兩者之間選擇一個小值作為 MSS
Nagle 算法
- 即使發(fā)送一個字節(jié)，也需要加入 tcp 頭和 ip 頭，也就是總字節(jié)數(shù)會使用 41 bytes，非常不經(jīng)濟。因此為了提高網(wǎng)絡(luò)利用率，tcp 希望盡可能發(fā)送足夠大的數(shù)據(jù)，這就是 Nagle 算法產(chǎn)生的緣由
- 該算法是指發(fā)送端即使還有應(yīng)該發(fā)送的數(shù)據(jù)，但如果這部分?jǐn)?shù)據(jù)很少的話，則進行延遲發(fā)送
- 如果 SO_SNDBUF 的數(shù)據(jù)達(dá)到 MSS，則需要發(fā)送
- 如果 SO_SNDBUF 中含有 FIN（表示需要連接關(guān)閉）這時將剩余數(shù)據(jù)發(fā)送，再關(guān)閉
- 如果 TCP_NODELAY = true，則需要發(fā)送
- 已發(fā)送的數(shù)據(jù)都收到 ack 時，則需要發(fā)送
- 上述條件不滿足，但發(fā)生超時（一般為 200ms）則需要發(fā)送
- 除上述情況，延遲發(fā)送
1.4 解決方案
- 短鏈接，發(fā)一個包建立一次連接，這樣連接建立到連接斷開之間就是消息的邊界，缺點效率太低
- 每一條消息采用固定長度，缺點浪費空間
- 每一條消息采用分隔符，例如 \n，缺點需要轉(zhuǎn)義
- 每一條消息分為 head 和 body，head 中包含 body 的長度
方法1，短鏈接
以解決粘包為例
public class HelloWorldClient {static final Logger log = LoggerFactory.getLogger(HelloWorldClient.class);public static void main(String[] args) {// 分 10 次發(fā)送for (int i = 0; i < 10; i++) {send();}}private static void send() {NioEventLoopGroup worker = new NioEventLoopGroup();try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {log.debug("conneted...");ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {log.debug("sending...");ByteBuf buffer = ctx.alloc().buffer();buffer.writeBytes(new byte[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15});ctx.writeAndFlush(buffer);// 發(fā)完即關(guān)ctx.channel().close();}});}});ChannelFuture channelFuture = bootstrap.connect("localhost", 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("client error", e);} finally {worker.shutdownGracefully();}}
}
輸出，略
半包用這種辦法還是解決不了，因為接收方的緩沖區(qū)大小是有限的（可再服務(wù)端通過如下方式調(diào)整netty的接收緩沖區(qū)，查看還是會出現(xiàn)半包現(xiàn)象：serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR, new AdaptiveRecvByteBufAllocator(16, 16, 16));
方法2，固定長度
客戶端的操作就是一次發(fā)送一個100字節(jié)長度的消息, 其中每10個字節(jié)表示一條消息（不夠10個字節(jié)的補位，湊夠10個字節(jié)）
服務(wù)端使用定長解碼器，每10個字節(jié)，湊夠1條消息，才給到下一個handler
客戶端代碼
@Slf4j
public class HelloWorldClient {public static void main(String[] args) {send();}private static void send() {NioEventLoopGroup worker = new NioEventLoopGroup();try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 會在連接 channel 建立成功之后，會觸發(fā) active事件@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {/*這里的操作就是發(fā)送一個100字節(jié)長度的消息, 其中每10個字節(jié)表示一條消息*/ByteBuf buf = ctx.alloc().buffer();char c = '0';Random r = new Random();for (int i = 0; i < 10; i++) {byte[] bytes = fill10Bytes(c, r.nextInt(10) + 1);c++;buf.writeBytes(bytes);}ctx.writeAndFlush(buf);}});}});ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("client error", e);} finally {worker.shutdownGracefully();}}// 填夠10個字節(jié)public static byte[] fill10Bytes(char c, int len) {byte[] bytes = new byte[10];Arrays.fill(bytes, (byte) '_');for (int i = 0; i < len; i++) {bytes[i] = (byte) c;}System.out.println(new String(bytes));return bytes;}
}服務(wù)端代碼
@Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss = new NioEventLoopGroup(1);NioEventLoopGroup worker = new NioEventLoopGroup();try {ServerBootstrap serverBootstrap = new ServerBootstrap();// 為現(xiàn)象明顯，服務(wù)端修改一下接收緩沖區(qū)，其它代碼不變// (調(diào)整系統(tǒng)的接收緩沖區(qū)（即滑動窗口）)// serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);// 調(diào)整netty的接收緩沖區(qū)// serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR,// new AdaptiveRecvByteBufAllocator(16, 16, 16));serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {// 注意順序: 要先添加定長的解碼處理器, 再添加日志處理器ch.pipeline().addLast(new FixedLengthFrameDecoder(10));ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));}});ChannelFuture channelFuture = serverBootstrap.bind(8080);log.debug("{} binding...", channelFuture.channel());channelFuture.sync();log.debug("{} bound...", channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("server error", e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug("stoped");}}public static void main(String[] args) {new HelloWorldServer().start();}
}
客戶端輸出，可以看到客戶端輸出，一次寫入了100個字節(jié)
Connected to the target VM, address: '127.0.0.1:50935', transport: 'socket'
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac] REGISTERED
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac] CONNECT: /127.0.0.1:8080
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac, L:/127.0.0.1:50973 - R:/127.0.0.1:8080] ACTIVE
000000____
111_______
2222222222
333333____
444_______
55________
6666666___
77777_____
8888______
99999_____
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac, L:/127.0.0.1:50973 - R:/127.0.0.1:8080] WRITE: 100B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 30 30 30 30 30 30 5f 5f 5f 5f 31 31 31 5f 5f 5f |000000____111___|
|00000010| 5f 5f 5f 5f 32 32 32 32 32 32 32 32 32 32 33 33 |____222222222233|
|00000020| 33 33 33 33 5f 5f 5f 5f 34 34 34 5f 5f 5f 5f 5f |3333____444_____|
|00000030| 5f 5f 35 35 5f 5f 5f 5f 5f 5f 5f 5f 36 36 36 36 |__55________6666|
|00000040| 36 36 36 5f 5f 5f 37 37 37 37 37 5f 5f 5f 5f 5f |666___77777_____|
|00000050| 38 38 38 38 5f 5f 5f 5f 5f 5f 39 39 39 39 39 5f |8888______99999_|
|00000060| 5f 5f 5f 5f |____ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0xdc9dffac, L:/127.0.0.1:50973 - R:/127.0.0.1:8080] FLUSH服務(wù)端輸出，重點看服務(wù)端輸出，服務(wù)端每10個字節(jié)接收作為一條消息，交給后面的handler處理，并沒有發(fā)生半包
13:51:21 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xafdaf078] binding...
13:51:21 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xafdaf078, L:/0:0:0:0:0:0:0:0:8080] bound...
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] REGISTERED
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] ACTIVE
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 30 30 30 30 30 30 5f 5f 5f 5f |000000____ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 31 31 31 5f 5f 5f 5f 5f 5f 5f |111_______ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 32 32 32 32 32 32 32 32 32 32 |2222222222 |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 33 33 33 33 33 33 5f 5f 5f 5f |333333____ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 34 34 34 5f 5f 5f 5f 5f 5f 5f |444_______ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 35 35 5f 5f 5f 5f 5f 5f 5f 5f |55________ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 36 36 36 36 36 36 36 5f 5f 5f |6666666___ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 37 37 37 37 37 5f 5f 5f 5f 5f |77777_____ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 38 38 38 38 5f 5f 5f 5f 5f 5f |8888______ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ: 10B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 39 39 39 39 39 5f 5f 5f 5f 5f |99999_____ |
+--------+-------------------------------------------------+----------------+
13:51:29 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x0d23d3d4, L:/127.0.0.1:8080 - R:/127.0.0.1:50973] READ COMPLETE缺點是，數(shù)據(jù)包的大小不好把握
- 長度定的太大，浪費
- 長度定的太小，對某些數(shù)據(jù)包又顯得不夠
方法3，固定分隔符
服務(wù)端代碼
- 服務(wù)端加入，默認(rèn)以 \n 或 \r\n 作為分隔符的處理器（如果超出最大長度仍未出現(xiàn)分隔符，則拋出異常）
@Slf4j
public class HelloWorldServer {void start() {NioEventLoopGroup boss = new NioEventLoopGroup(1);NioEventLoopGroup worker = new NioEventLoopGroup();try {ServerBootstrap serverBootstrap = new ServerBootstrap();// 為現(xiàn)象明顯，服務(wù)端修改一下接收緩沖區(qū)，其它代碼不變// (調(diào)整系統(tǒng)的接收緩沖區(qū)（即滑動窗口）)// serverBootstrap.option(ChannelOption.SO_RCVBUF, 10);// 調(diào)整netty的接收緩沖區(qū)// serverBootstrap.childOption(ChannelOption.RCVBUF_ALLOCATOR,// new AdaptiveRecvByteBufAllocator(16, 16, 16));serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {// 注意順序: 要先添加基于分隔符的解碼處理器, 再添加日志處理器ch.pipeline().addLast(new LineBasedFrameDecoder(1024));ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));}});ChannelFuture channelFuture = serverBootstrap.bind(8080);log.debug("{} binding...", channelFuture.channel());channelFuture.sync();log.debug("{} bound...", channelFuture.channel());channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("server error", e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();log.debug("stoped");}}public static void main(String[] args) {new HelloWorldServer().start();}
}客戶端代碼
客戶端在每條消息之后，加入 \n 分隔符
@Slf4j
public class HelloWorldClient {public static void main(String[] args) {send();}private static void send() {NioEventLoopGroup worker = new NioEventLoopGroup();try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 會在連接 channel 建立成功之后，會觸發(fā) active事件@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {/*在每條消息后面加上1個\n, 來表示消息的分隔符*/ByteBuf buf = ctx.alloc().buffer();char c = '0';Random r = new Random();for (int i = 0; i < 10; i++) {StringBuilder sb = makeString(c, r.nextInt(256) + 1);buf.writeBytes(sb.toString().getBytes());c++;}// 還是1次性寫入bufctx.writeAndFlush(buf);}});}});ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("client error", e);} finally {worker.shutdownGracefully();}}public static StringBuilder makeString(char c, int len) {StringBuilder sb = new StringBuilder(len + 2);for (int i = 0; i < len; i++) {sb.append(c);}sb.append("\n");return sb;}
}
客戶端輸出
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a] REGISTERED
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a] CONNECT: /127.0.0.1:8080
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a, L:/127.0.0.1:54341 - R:/127.0.0.1:8080] ACTIVE
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a, L:/127.0.0.1:54341 - R:/127.0.0.1:8080] WRITE: 1445B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000010| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000020| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000030| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000040| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000050| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000060| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000070| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000080| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000090| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000a0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000b0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000c0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000d0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000e0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000f0| 30 30 30 30 0a 31 31 31 31 31 31 31 31 31 31 31 |0000.11111111111|
|00000100| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000110| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000120| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000130| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000140| 31 31 31 31 31 31 31 31 31 31 31 31 31 0a 32 32 |1111111111111.22|
|00000150| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000160| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000170| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000180| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000190| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001a0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001b0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001c0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001d0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001e0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000001f0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000200| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000210| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000220| 32 32 0a 33 33 33 33 33 33 33 33 33 33 33 33 33 |22.3333333333333|
|00000230| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000240| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000250| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000260| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000270| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000280| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000290| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002a0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002b0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002c0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002d0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002e0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000002f0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000300| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000310| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000320| 0a 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |.444444444444444|
|00000330| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000340| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000350| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000360| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000370| 34 34 0a 35 35 35 35 35 35 35 35 35 35 35 35 35 |44.5555555555555|
|00000380| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000390| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003a0| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003b0| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003c0| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|000003d0| 35 35 35 35 35 35 35 0a 36 36 36 36 36 36 36 36 |5555555.66666666|
|000003e0| 36 36 36 36 36 36 0a 37 37 37 37 37 37 37 37 37 |666666.777777777|
|000003f0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000400| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000410| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000420| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000430| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000440| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000450| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000460| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000470| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000480| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000490| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004a0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004b0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004c0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000004d0| 37 0a 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |7.88888888888888|
|000004e0| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|000004f0| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000500| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000510| 38 38 38 38 38 38 38 0a 39 39 39 39 39 39 39 39 |8888888.99999999|
|00000520| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000530| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000540| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000550| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000560| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000570| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000580| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000590| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|000005a0| 39 39 39 39 0a |9999. |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x45f4846a, L:/127.0.0.1:54341 - R:/127.0.0.1:8080] FLUSH服務(wù)端輸出
14:27:25 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xd4acc436] binding...
14:27:25 [DEBUG] [main] c.z.a.HelloWorldServer - [id: 0xd4acc436, L:/0:0:0:0:0:0:0:0:8080] bound...
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] REGISTERED
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] ACTIVE
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 244B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000010| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000020| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000030| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000040| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000050| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000060| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000070| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000080| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|00000090| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000a0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000b0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000c0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000d0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000e0| 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 |0000000000000000|
|000000f0| 30 30 30 30 |0000 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 88B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000010| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000020| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000030| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000040| 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 |1111111111111111|
|00000050| 31 31 31 31 31 31 31 31 |11111111 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 212B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000010| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000020| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000030| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000040| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000050| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000060| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000070| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000080| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|00000090| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000a0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000b0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000c0| 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 |2222222222222222|
|000000d0| 32 32 32 32 |2222 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 253B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000010| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000020| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000030| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000040| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000050| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000060| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000070| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000080| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|00000090| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000a0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000b0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000c0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000d0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000e0| 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333333|
|000000f0| 33 33 33 33 33 33 33 33 33 33 33 33 33 |3333333333333 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 81B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000010| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000020| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000030| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000040| 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 |4444444444444444|
|00000050| 34 |4 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 100B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000010| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000020| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000030| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000040| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000050| 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 35 |5555555555555555|
|00000060| 35 35 35 35 |5555 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 14B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 36 36 36 36 36 36 36 36 36 36 36 36 36 36 |66666666666666 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 234B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000010| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000020| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000030| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000040| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000050| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000060| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000070| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000080| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|00000090| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000a0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000b0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000c0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000d0| 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 37 |7777777777777777|
|000000e0| 37 37 37 37 37 37 37 37 37 37 |7777777777 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 69B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000010| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000020| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000030| 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 38 |8888888888888888|
|00000040| 38 38 38 38 38 |88888 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ: 140B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000010| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000020| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000030| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000040| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000050| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000060| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000070| 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 39 |9999999999999999|
|00000080| 39 39 39 39 39 39 39 39 39 39 39 39 |999999999999 |
+--------+-------------------------------------------------+----------------+
14:27:28 [DEBUG] [nioEventLoopGroup-3-1] i.n.h.l.LoggingHandler - [id: 0x8dfc81f2, L:/127.0.0.1:8080 - R:/127.0.0.1:54341] READ COMPLETE缺點，處理字符數(shù)據(jù)比較合適，但如果內(nèi)容本身包含了分隔符（字節(jié)數(shù)據(jù)常常會有此情況），那么就會解析錯誤
方法4，預(yù)設(shè)長度
在發(fā)送消息前，先約定用定長字節(jié)表示接下來數(shù)據(jù)的長度
LengthFieldBasedFrameDecoder
-
lengthFieldOffset - 長度字段偏移量
-
lengthFieldLength - 長度字段長度
-
lengthAdjustment - 長度字段為基準(zhǔn)，還要跳過幾個字節(jié)才是內(nèi)容
-
initialBytesTostrip - 從頭剝離幾個字節(jié)
// 最大長度，長度偏移，長度占用字節(jié)，長度調(diào)整，剝離字節(jié)數(shù)
ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(1024, 0, 1, 0, 1));
測試示例，使用EmbeddedChannel模擬
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.embedded.EmbeddedChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;public class TestLengthFieldDecoder {public static void main(String[] args) {// 注意處理器的添加順序EmbeddedChannel channel = new EmbeddedChannel(new LengthFieldBasedFrameDecoder(1024, 0, 4, 1, 5),new LoggingHandler(LogLevel.DEBUG));// 4 個字節(jié)的內(nèi)容長度， 實際內(nèi)容ByteBuf buffer = ByteBufAllocator.DEFAULT.buffer();// 模擬對方發(fā)送過來消息send(buffer, "Hello, world");send(buffer, "Hi!");// 把消息寫入channelchannel.writeInbound(buffer);}private static void send(ByteBuf buffer, String content) {// 實際內(nèi)容byte[] bytes = content.getBytes();// 實際內(nèi)容長度int length = bytes.length;// 寫入內(nèi)容長度buffer.writeInt(length);// 寫入版本號buffer.writeByte(1);// 寫入實際內(nèi)容buffer.writeBytes(bytes);}
}
// 輸出
/*
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] REGISTERED
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] ACTIVE
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 12B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 |Hello, world |
+--------+-------------------------------------------------+----------------+
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 3B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 48 69 21 |Hi! |
+--------+-------------------------------------------------+----------------+
16:09:07 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ COMPLETE
*/
2. 協(xié)議設(shè)計與解析
2.1 為什么需要協(xié)議？
TCP/IP 中消息傳輸基于流的方式，沒有邊界。
協(xié)議的目的就是劃定消息的邊界，制定通信雙方要共同遵守的通信規(guī)則
例如：在網(wǎng)絡(luò)上傳輸
下雨天留客天留我不留
是中文一句著名的無標(biāo)點符號句子，在沒有標(biāo)點符號情況下，這句話有數(shù)種拆解方式，而意思卻是完全不同，所以常被用作講述標(biāo)點符號的重要性
一種解讀
下雨天留客，天留，我不留
另一種解讀
下雨天，留客天，留我不？留
如何設(shè)計協(xié)議呢？其實就是給網(wǎng)絡(luò)傳輸?shù)男畔⒓由稀皹?biāo)點符號”。但通過分隔符來斷句不是很好，因為分隔符本身如果用于傳輸，那么必須加以區(qū)分。因此，下面一種協(xié)議較為常用
定長字節(jié)表示內(nèi)容長度 + 實際內(nèi)容
例如，假設(shè)一個中文字符長度為 3，按照上述協(xié)議的規(guī)則，發(fā)送信息方式如下，就不會被接收方弄錯意思了
0f下雨天留客06天留09我不留
小故事
很久很久以前，一位私塾先生到一家任教。雙方簽訂了一紙協(xié)議：“無雞鴨亦可無魚肉亦可白菜豆腐不可少不得束修金”。此后，私塾先生雖然認(rèn)真教課，但主人家則總是給私塾先生以白菜豆腐為菜，絲毫未見雞鴨魚肉的款待。私塾先生先是很不解，可是后來也就想通了：主人把雞鴨魚肉的錢都會換為束修金的，也罷。至此雙方相安無事。
年關(guān)將至，一個學(xué)年段亦告結(jié)束。私塾先生臨行時，也不見主人家為他交付束修金，遂與主家理論。然主家亦振振有詞：“有協(xié)議為證——無雞鴨亦可，無魚肉亦可，白菜豆腐不可少，不得束修金。這白紙黑字明擺著的，你有什么要說的呢？”
私塾先生據(jù)理力爭：“協(xié)議是這樣的——無雞，鴨亦可；無魚，肉亦可；白菜豆腐不可，少不得束修金?！?/p>
雙方唇槍舌戰(zhàn)，你來我往，真?zhèn)€是不亦樂乎！
這里的束修金，也作“束脩”，應(yīng)當(dāng)是泛指教師應(yīng)當(dāng)?shù)玫降膱蟪?/p>
2.2 redis 協(xié)議舉例
使用netty編寫客戶端，連接redis，并且發(fā)送set aaa bbb，get aaa 這2個命令
@Slf4j
public class TestRedis {/*set name zhangsan*3 （3個元素 \r\n）$3 （第一個元素3個字節(jié) \r\n）set （set 3個字節(jié)）$4 （第二個元素4個字節(jié) \r\n）name（name 4個字節(jié)）$8 （第三個元素8個字節(jié) \r\n）zhangsan（zhangsan 8個字節(jié)）*/public static void main(String[] args) {NioEventLoopGroup worker = new NioEventLoopGroup();byte[] LINE = new byte[]{13, 10};System.out.println(LINE_BYTES[0] == '\r');System.out.println(LINE_BYTES[1] == '\n');try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(worker);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) {ch.pipeline().addLast(new LoggingHandler());ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {// 會在連接 channel 建立成功后，會觸發(fā) active 事件@Overridepublic void channelActive(ChannelHandlerContext ctx) {// 執(zhí)行命令: set aaa bbbset(ctx);// 執(zhí)行命令: get aaaget(ctx);}private void get(ChannelHandlerContext ctx) {ByteBuf buf = ctx.alloc().buffer();buf.writeBytes("*2".getBytes());buf.writeBytes(LINE);buf.writeBytes("$3".getBytes());buf.writeBytes(LINE);buf.writeBytes("get".getBytes());buf.writeBytes(LINE);buf.writeBytes("$3".getBytes());buf.writeBytes(LINE);buf.writeBytes("aaa".getBytes());buf.writeBytes(LINE);ctx.writeAndFlush(buf);}private void set(ChannelHandlerContext ctx) {ByteBuf buf = ctx.alloc().buffer();buf.writeBytes("*3".getBytes());buf.writeBytes(LINE);buf.writeBytes("$3".getBytes());buf.writeBytes(LINE);buf.writeBytes("set".getBytes());buf.writeBytes(LINE);buf.writeBytes("$3".getBytes());buf.writeBytes(LINE);buf.writeBytes("aaa".getBytes());buf.writeBytes(LINE);buf.writeBytes("$3".getBytes());buf.writeBytes(LINE);buf.writeBytes("bbb".getBytes());buf.writeBytes(LINE); // 注意：最后面的這個\r\n也不能省略ctx.writeAndFlush(buf); }@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {ByteBuf buf = (ByteBuf) msg;System.out.println(buf.toString(Charset.defaultCharset()));// 我覺得這里應(yīng)該需要釋放buf吧??}});}});ChannelFuture channelFuture = bootstrap.connect("localhost", 6379).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {log.error("client error", e);} finally {worker.shutdownGracefully(); // 優(yōu)雅關(guān)閉}}
}
// 輸出日志
/*12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1] REGISTERED
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1] CONNECT: localhost/127.0.0.1:6379
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] ACTIVE
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] WRITE: 31B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 2a 33 0d 0a 24 33 0d 0a 73 65 74 0d 0a 24 33 0d |*3..$3..set..$3.|
|00000010| 0a 61 61 61 0d 0a 24 33 0d 0a 62 62 62 0d 0a |.aaa..$3..bbb.. |
+--------+-------------------------------------------------+----------------+
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] FLUSH
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] WRITE: 22B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 2a 32 0d 0a 24 33 0d 0a 67 65 74 0d 0a 24 33 0d |*2..$3..get..$3.|
|00000010| 0a 61 61 61 0d 0a |.aaa.. |
+--------+-------------------------------------------------+----------------+
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] FLUSH
12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] READ: 14B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 2b 4f 4b 0d 0a 24 33 0d 0a 62 62 62 0d 0a |+OK..$3..bbb.. |
+--------+-------------------------------------------------+----------------+
+OK
$3
bbb12:57:21 [DEBUG] [nioEventLoopGroup-2-1] i.n.h.l.LoggingHandler - [id: 0x80c5b3b1, L:/127.0.0.1:58542 - R:localhost/127.0.0.1:6379] READ COMPLETE*/
2.3 http 協(xié)議舉例
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.*;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import lombok.extern.slf4j.Slf4j;@Slf4j
public class TestHttp {public static void main(String[] args) throws InterruptedException {NioEventLoopGroup boss = new NioEventLoopGroup(1);NioEventLoopGroup worker = new NioEventLoopGroup();try {ServerBootstrap serverBootstrap = new ServerBootstrap().group(boss, worker).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new LoggingHandler(LogLevel.DEBUG));// 配置http編解碼器（包括編碼、解碼）// 解碼 - 把發(fā)向服務(wù)端的請求ByteBuf解碼// 編碼 - 把發(fā)給客戶端的數(shù)據(jù)編碼成ByteBuf, 以便寫出字節(jié)數(shù)據(jù)// （HttpServerCodec繼承自CombinedChannelDuplexHandler<HttpRequestDecoder,// HttpResponseEncoder>）ch.pipeline().addLast(new HttpServerCodec());// 注意寫入的泛型, 表示該處理器只處理該類型的消息ch.pipeline().addLast(new SimpleChannelInboundHandler<HttpRequest>() {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, HttpRequest msg) throws Exception {// 獲取請求urilog.info(msg.uri());// 響應(yīng)對象DefaultFullHttpResponse response = new DefaultFullHttpResponse(msg.protocolVersion(), HttpResponseStatus.OK);byte[] content = "<h1>hello,world</h1>".getBytes();response.content().writeBytes(content);// 告訴瀏覽器, 響應(yīng)內(nèi)容就這么長, 不然瀏覽器會一直傻傻的等待接收后面的內(nèi)容// （網(wǎng)站圖標(biāo)位置一直在轉(zhuǎn)圈圈）response.headers().set(HttpHeaderNames.CONTENT_LENGTH, content.length);// 寫回響應(yīng)// （這個response將會經(jīng)過HttpServerCodec出站處理器，將它編碼了，// 再返回回去）ctx.writeAndFlush(response);}});/*// 當(dāng)瀏覽器發(fā)起1個get請求后, 該處理器的channelRead方法被調(diào)用了2次，// - 第一次傳過來的msg是 DefaultHttpRequest(decodeResult: success,version: HTTP/1.1)// - 第二次傳過來的是 EmptyLastHttpContentch.pipeline().addLast(new ChannelInboundHandlerAdapter() {@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {log.info("接收到請求: {}", msg);// HttpServerCodec會把接收到的請求, // 分為 HttpRequest 和 HttpContent(對該handler進行了2次調(diào)用)// 如果只處理其中某一種類型的消息，可以如上使用// SimpleChannelInboundHandler，// 并指定泛型（比如上面就指定了HttpRequest）if (msg instanceof HttpRequest) { // 請求行 和 請求頭log.info("HttpRequest msg: {}", msg);} else if (msg instanceof HttpContent) { // 請求體log.info("HttpContent msg: {}", msg);}}});*/}});ChannelFuture channelFuture = serverBootstrap.bind(8080).sync();channelFuture.channel().closeFuture().sync();} catch (InterruptedException e) {e.printStackTrace();} finally {boss.shutdownGracefully();worker.shutdownGracefully();}}
}
2.4 自定義協(xié)議要素
- 魔數(shù)，用來在第一時間判定是否是無效數(shù)據(jù)包
- 版本號，可以支持協(xié)議的升級
- 序列化算法，消息正文到底采用哪種序列化反序列化方式，可以由此擴展，例如：json、protobuf、hessian、jdk
- 指令類型，是登錄、注冊、單聊、群聊… 跟業(yè)務(wù)相關(guān)
- 請求序號，為了雙工通信，提供異步能力
- 正文長度
- 消息正文
編解碼器
根據(jù)上面的要素，設(shè)計一個登錄請求消息和登錄響應(yīng)消息，并使用 Netty 完成收發(fā)
MessageCodec
@Slf4j
public class MessageCodec extends ByteToMessageCodec<Message> {@Overridepublic void encode(ChannelHandlerContext ctx, Message msg, ByteBuf out) throws Exception {// 1. 4 字節(jié)的魔數(shù)out.writeBytes(new byte[]{1, 2, 3, 4});// 2. 1 字節(jié)的版本,out.writeByte(1);// 3. 1 字節(jié)的序列化方式 jdk 0 , json 1out.writeByte(0);// 4. 1 字節(jié)的指令類型out.writeByte(msg.getMessageType());// 5. 4 個字節(jié)out.writeInt(msg.getSequenceId());// 無意義，對齊填充，為了滿2^n固定字節(jié)數(shù), 正好湊夠16個固定字節(jié)數(shù)out.writeByte(0xff);/* 將Message對象先轉(zhuǎn)為字節(jié)數(shù)組(使用ByteArrayOutputStream + ObjectOutputStream),然后把字節(jié)數(shù)組寫到ByteBuf中 */// 6. 獲取內(nèi)容的字節(jié)數(shù)組ByteArrayOutputStream bos = new ByteArrayOutputStream();ObjectOutputStream oos = new ObjectOutputStream(bos);oos.writeObject(msg);byte[] bytes = bos.toByteArray();// 7. 長度out.writeInt(bytes.length);// 8. 寫入內(nèi)容out.writeBytes(bytes);log.info("message 編碼完成...{}", msg);}@Overrideprotected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {// 讀取 4 字節(jié)的魔數(shù)（讀指針向后移動4位）int magicNum = in.readInt();// 讀取 1 字節(jié)的版本byte version = in.readByte();// 讀取 1 字節(jié)的序列化方式byte serializerType = in.readByte();// 讀取 1 字節(jié)的指令類型byte messageType = in.readByte();// 讀取 4 個字節(jié) 序列idint sequenceId = in.readInt();// 讀取 無意義 的字節(jié)（將讀指針向后移動1位）in.readByte();// 讀取 長度int length = in.readInt();// 使用讀取到的長度創(chuàng)建字節(jié)數(shù)組byte[] bytes = new byte[length];// 將ByteBuf讀取到字節(jié)數(shù)組in.readBytes(bytes, 0, length);/* 這里將ByteBuf的數(shù)據(jù), 通過jdk反序列化的方式, 轉(zhuǎn)為java對象,那就要保證這個數(shù)據(jù)一定是對象完整的序列化字節(jié)數(shù)據(jù),如果不是一個完整的數(shù)據(jù)（即出現(xiàn)半包的情況）, 那就廢了。因此，*/// jdk反序列化 將字節(jié)數(shù)組 轉(zhuǎn)為 Message對象ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(bytes));Message message = (Message) ois.readObject();log.debug("{}, {}, {}, {}, {}, {}", magicNum, version, serializerType, messageType, sequenceId, length);log.debug("message 解碼完成{}", message);// 將消息添加到out集合當(dāng)中out.add(message);}
}
TestMessageCodec
@Slf4j
public class TestMessageCodec {public static void main(String[] args) throws Exception {EmbeddedChannel channel = new EmbeddedChannel(new LoggingHandler(),// 參數(shù)的含義：數(shù)據(jù)的最大長度為1024個字節(jié)、從索引0開始,偏移12個字節(jié)開始,是實際內(nèi)容長度信息、// 實際內(nèi)容長度占4個字節(jié)、不做調(diào)整(即不偏移,實際內(nèi)容長度后面開始就是實際內(nèi)容)、// 不剝離前面的字節(jié)（因為在MessageCodec中有解析前面的字節(jié)）// 幀解碼器，解決粘包&半包問題// （如果發(fā)現(xiàn)數(shù)據(jù)不完整(即發(fā)生了半包問題), 它是不會把消息傳遞給下一個處理器處理的,// 等數(shù)據(jù)完整了，它才會把完整的消息發(fā)給下一個處理器）// 此處可用來解決半包的問題: 也就是說, 實際內(nèi)容長度可能有239個字節(jié), 但是本次只收到了100個字節(jié),// 那如果往后面讀的話, 就讀不滿239個字節(jié), 那就等接收到下一次消息后,// 一直到滿了239個字節(jié), 再把這個完整的消息, 傳遞給下一個handlernew LengthFieldBasedFrameDecoder(1024, 12, 4, 0, 0),// 自定義編解碼器new MessageCodec());log.info("------------------測試編碼-----------------");// 測試encodeLoginRequestMessage message = new LoginRequestMessage("zhangsan", "123");// 向channel中寫出數(shù)據(jù)（MessageCodec會對message作編碼處理，寫入到ByteBuf）channel.writeOutbound(message);log.info("------------------測試解碼-----------------");// 測試decode// 先使用MessageCodec將message寫入到ByteBufByteBuf buf = ByteBufAllocator.DEFAULT.buffer();new MessageCodec().encode(null, message, buf);// 將buf切片成2部分, 模擬半包(先接收100字節(jié), 然后再接收剩下的字節(jié)),// 注意: 須使用LengthFieldBasedFrameDecoder處理半包問題ByteBuf s1 = buf.slice(0, 100);ByteBuf s2 = buf.slice(100, buf.readableBytes() - 100);s1.retain(); // 引用計數(shù)+1（即現(xiàn)在為2）// 這個方法默認(rèn)會釋放buf（release 1）,接收半包后的數(shù)據(jù)時,buf被釋放了就會報錯(下面這句會報錯)// 因此上面就使用了s1.retain()讓引用計數(shù)+1了channel.writeInbound(s1);channel.writeInbound(s2);}
}
輸出
觀察下面的輸出
- 編碼的時候, 寫出了224個字節(jié)
- 解碼的時候，接受了2次，第一次接受收了100個字節(jié)，第二次接收了124個字節(jié)，并且只出現(xiàn)了1次解碼完成，這說明在出現(xiàn)了半包的情況下LengthFieldBasedFrameDecoder幫助我們解決了半包問題，并且它會接收一個完整的包后，才會傳給后面的handler
- 可以留意一下，在寫出的時候，第一行的字節(jié)數(shù)據(jù) 正好 符合 我們的編碼規(guī)則哦
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] REGISTERED
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] ACTIVE
21:50:22 [INFO ] [main] c.i.a.c.TestMessageCodec - ------------------測試編碼-----------------
21:50:22 [INFO ] [main] c.i.p.MessageCodec - message 編碼完成...LoginRequestMessage(super=Message(sequenceId=0, messageType=0), username=zhangsan, password=123)
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] WRITE: 214B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 01 02 03 04 01 00 00 00 00 00 00 ff 00 00 00 c6 |................|
|00000010| ac ed 00 05 73 72 00 25 63 6e 2e 69 74 63 61 73 |....sr.%cn.itcas|
|00000020| 74 2e 6d 65 73 73 61 67 65 2e 4c 6f 67 69 6e 52 |t.message.LoginR|
|00000030| 65 71 75 65 73 74 4d 65 73 73 61 67 65 a0 3f 71 |equestMessage.?q|
|00000040| cb 31 45 b5 88 02 00 02 4c 00 08 70 61 73 73 77 |.1E.....L..passw|
|00000050| 6f 72 64 74 00 12 4c 6a 61 76 61 2f 6c 61 6e 67 |ordt..Ljava/lang|
|00000060| 2f 53 74 72 69 6e 67 3b 4c 00 08 75 73 65 72 6e |/String;L..usern|
|00000070| 61 6d 65 71 00 7e 00 01 78 72 00 19 63 6e 2e 69 |ameq.~..xr..cn.i|
|00000080| 74 63 61 73 74 2e 6d 65 73 73 61 67 65 2e 4d 65 |tcast.message.Me|
|00000090| 73 73 61 67 65 3d dd 19 a0 bc 07 47 cb 02 00 02 |ssage=.....G....|
|000000a0| 49 00 0b 6d 65 73 73 61 67 65 54 79 70 65 49 00 |I..messageTypeI.|
|000000b0| 0a 73 65 71 75 65 6e 63 65 49 64 78 70 00 00 00 |.sequenceIdxp...|
|000000c0| 00 00 00 00 00 74 00 03 31 32 33 74 00 08 7a 68 |.....t..123t..zh|
|000000d0| 61 6e 67 73 61 6e |angsan |
+--------+-------------------------------------------------+----------------+
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] FLUSH
21:50:22 [INFO ] [main] c.i.a.c.TestMessageCodec - ------------------測試解碼-----------------
21:50:22 [INFO ] [main] c.i.p.MessageCodec - message 編碼完成...LoginRequestMessage(super=Message(sequenceId=0, messageType=0), username=zhangsan, password=123)
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 100B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 01 02 03 04 01 00 00 00 00 00 00 ff 00 00 00 c6 |................|
|00000010| ac ed 00 05 73 72 00 25 63 6e 2e 69 74 63 61 73 |....sr.%cn.itcas|
|00000020| 74 2e 6d 65 73 73 61 67 65 2e 4c 6f 67 69 6e 52 |t.message.LoginR|
|00000030| 65 71 75 65 73 74 4d 65 73 73 61 67 65 a0 3f 71 |equestMessage.?q|
|00000040| cb 31 45 b5 88 02 00 02 4c 00 08 70 61 73 73 77 |.1E.....L..passw|
|00000050| 6f 72 64 74 00 12 4c 6a 61 76 61 2f 6c 61 6e 67 |ordt..Ljava/lang|
|00000060| 2f 53 74 72 |/Str |
+--------+-------------------------------------------------+----------------+
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ COMPLETE
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ: 114B+-------------------------------------------------+| 0 1 2 3 4 5 6 7 8 9 a b c d e f |
+--------+-------------------------------------------------+----------------+
|00000000| 69 6e 67 3b 4c 00 08 75 73 65 72 6e 61 6d 65 71 |ing;L..usernameq|
|00000010| 00 7e 00 01 78 72 00 19 63 6e 2e 69 74 63 61 73 |.~..xr..cn.itcas|
|00000020| 74 2e 6d 65 73 73 61 67 65 2e 4d 65 73 73 61 67 |t.message.Messag|
|00000030| 65 3d dd 19 a0 bc 07 47 cb 02 00 02 49 00 0b 6d |e=.....G....I..m|
|00000040| 65 73 73 61 67 65 54 79 70 65 49 00 0a 73 65 71 |essageTypeI..seq|
|00000050| 75 65 6e 63 65 49 64 78 70 00 00 00 00 00 00 00 |uenceIdxp.......|
|00000060| 00 74 00 03 31 32 33 74 00 08 7a 68 61 6e 67 73 |.t..123t..zhangs|
|00000070| 61 6e |an |
+--------+-------------------------------------------------+----------------+
21:50:22 [DEBUG] [main] c.i.p.MessageCodec - 16909060, 1, 0, 0, 0, 198
21:50:22 [DEBUG] [main] c.i.p.MessageCodec - message 解碼完成LoginRequestMessage(super=Message(sequenceId=0, messageType=0), username=zhangsan, password=123)
21:50:22 [DEBUG] [main] i.n.h.l.LoggingHandler - [id: 0xembedded, L:embedded - R:embedded] READ COMPLETE
💡 什么時候可以加 @Sharable
- 當(dāng) handler 不保存狀態(tài)時，就可以安全地在多線程下被共享
- 但要注意對于編解碼器類，不能繼承 ByteToMessageCodec 或 CombinedChannelDuplexHandler 父類，他們的構(gòu)造方法對 @Sharable 有限制
- 如果能確保編解碼器不會保存狀態(tài)，可以繼承 MessageToMessageCodec 父類
@Slf4j
@ChannelHandler.Sharable
/*** 必須和 LengthFieldBasedFrameDecoder 一起使用，確保接到的 ByteBuf 消息是完整的*/
public class MessageCodecSharable extends MessageToMessageCodec<ByteBuf, Message> {@Overrideprotected void encode(ChannelHandlerContext ctx, Message msg, List<Object> outList) throws Exception {ByteBuf out = ctx.alloc().buffer();// 1. 4 字節(jié)的魔數(shù)out.writeBytes(new byte[]{1, 2, 3, 4});// 2. 1 字節(jié)的版本,out.writeByte(1);// 3. 1 字節(jié)的序列化方式 jdk 0 , json 1out.writeByte(0);// 4. 1 字節(jié)的指令類型out.writeByte(msg.getMessageType());// 5. 4 個字節(jié)out.writeInt(msg.getSequenceId());// 無意義，對齊填充out.writeByte(0xff);// 6. 獲取內(nèi)容的字節(jié)數(shù)組ByteArrayOutputStream bos = new ByteArrayOutputStream();ObjectOutputStream oos = new ObjectOutputStream(bos);oos.writeObject(msg);byte[] bytes = bos.toByteArray();// 7. 長度out.writeInt(bytes.length);// 8. 寫入內(nèi)容out.writeBytes(bytes);outList.add(out);}@Overrideprotected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {int magicNum = in.readInt();byte version = in.readByte();byte serializerType = in.readByte();byte messageType = in.readByte();int sequenceId = in.readInt();in.readByte();int length = in.readInt();byte[] bytes = new byte[length];in.readBytes(bytes, 0, length);ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(bytes));Message message = (Message) ois.readObject();log.debug("{}, {}, {}, {}, {}, {}", magicNum, version, serializerType, messageType, sequenceId, length);log.debug("{}", message);out.add(message);}
}
3. 聊天室案例
3.1 聊天室業(yè)務(wù)介紹
/*** 用戶管理接口*/
public interface UserService {/*** 登錄* @param username 用戶名* @param password 密碼* @return 登錄成功返回 true, 否則返回 false*/boolean login(String username, String password);
}
/*** 會話管理接口*/
public interface Session {/*** 綁定會話* @param channel 哪個 channel 要綁定會話* @param username 會話綁定用戶*/void bind(Channel channel, String username);/*** 解綁會話* @param channel 哪個 channel 要解綁會話*/void unbind(Channel channel);/*** 獲取屬性* @param channel 哪個 channel* @param name 屬性名* @return 屬性值*/Object getAttribute(Channel channel, String name);/*** 設(shè)置屬性* @param channel 哪個 channel* @param name 屬性名* @param value 屬性值*/void setAttribute(Channel channel, String name, Object value);/*** 根據(jù)用戶名獲取 channel* @param username 用戶名* @return channel*/Channel getChannel(String username);
}
/*** 聊天組會話管理接口*/
public interface GroupSession {/*** 創(chuàng)建一個聊天組, 如果不存在才能創(chuàng)建成功, 否則返回 null* @param name 組名* @param members 成員* @return 成功時返回組對象, 失敗返回 null*/Group createGroup(String name, Set<String> members);/*** 加入聊天組* @param name 組名* @param member 成員名* @return 如果組不存在返回 null, 否則返回組對象*/Group joinMember(String name, String member);/*** 移除組成員* @param name 組名* @param member 成員名* @return 如果組不存在返回 null, 否則返回組對象*/Group removeMember(String name, String member);/*** 移除聊天組* @param name 組名* @return 如果組不存在返回 null, 否則返回組對象*/Group removeGroup(String name);/*** 獲取組成員* @param name 組名* @return 成員集合, 沒有成員會返回 empty set*/Set<String> getMembers(String name);/*** 獲取組成員的 channel 集合, 只有在線的 channel 才會返回* @param name 組名* @return 成員 channel 集合*/List<Channel> getMembersChannel(String name);
}
3.2 聊天室業(yè)務(wù)-登錄
@Slf4j
public class ChatServer {public static void main(String[] args) {NioEventLoopGroup boss = new NioEventLoopGroup();NioEventLoopGroup worker = new NioEventLoopGroup();LoggingHandler LOGGING_HANDLER = new LoggingHandler(LogLevel.DEBUG);MessageCodecSharable MESSAGE_CODEC = new MessageCodecSharable();try {ServerBootstrap serverBootstrap = new ServerBootstrap();serverBootstrap.channel(NioServerSocketChannel.class);serverBootstrap.group(boss, worker);serverBootstrap.childHandler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new ProcotolFrameDecoder());ch.pipeline().addLast(LOGGING_HANDLER);ch.pipeline().addLast(MESSAGE_CODEC);ch.pipeline().addLast(new SimpleChannelInboundHandler<LoginRequestMessage>() {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, LoginRequestMessage msg) throws Exception {String username = msg.getUsername();String password = msg.getPassword();boolean login = UserServiceFactory.getUserService().login(username, password);LoginResponseMessage message;if(login) {message = new LoginResponseMessage(true, "登錄成功");} else {message = new LoginResponseMessage(false, "用戶名或密碼不正確");}ctx.writeAndFlush(message);}});}});Channel channel = serverBootstrap.bind(8080).sync().channel();channel.closeFuture().sync();} catch (InterruptedException e) {log.error("server error", e);} finally {boss.shutdownGracefully();worker.shutdownGracefully();}}
}
@Slf4j
public class ChatClient {public static void main(String[] args) {NioEventLoopGroup group = new NioEventLoopGroup();LoggingHandler LOGGING_HANDLER = new LoggingHandler(LogLevel.DEBUG);MessageCodecSharable MESSAGE_CODEC = new MessageCodecSharable();CountDownLatch WAIT_FOR_LOGIN = new CountDownLatch(1);AtomicBoolean LOGIN = new AtomicBoolean(false);try {Bootstrap bootstrap = new Bootstrap();bootstrap.channel(NioSocketChannel.class);bootstrap.group(group);bootstrap.handler(new ChannelInitializer<SocketChannel>() {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ch.pipeline().addLast(new ProcotolFrameDecoder());
// ch.pipeline().addLast(LOGGING_HANDLER);ch.pipeline().addLast(MESSAGE_CODEC);ch.pipeline().addLast("client handler", new ChannelInboundHandlerAdapter() {// 接收響應(yīng)消息@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {log.debug("msg: {}", msg);if ((msg instanceof LoginResponseMessage)) {LoginResponseMessage response = (LoginResponseMessage) msg;if (response.isSuccess()) {// 如果登錄成功LOGIN.set(true);}// 喚醒 system in 線程WAIT_FOR_LOGIN.countDown();}}// 在連接建立后觸發(fā) active 事件@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {// 負(fù)責(zé)接收用戶在控制臺的輸入，負(fù)責(zé)向服務(wù)器發(fā)送各種消息new Thread(() -> {Scanner scanner = new Scanner(System.in);System.out.println("請輸入用戶名:");String username = scanner.nextLine();System.out.println("請輸入密碼:");String password = scanner.nextLine();// 構(gòu)造消息對象LoginRequestMessage message = new LoginRequestMessage(username, password);// 發(fā)送消息ctx.writeAndFlush(message);System.out.println("等待后續(xù)操作...");try {WAIT_FOR_LOGIN.await();} catch (InterruptedException e) {e.printStackTrace();}// 如果登錄失敗if (!LOGIN.get()) {ctx.channel().close();return;}while (true) {System.out.println("==================================");System.out.println("send [username] [content]");System.out.println("gsend [group name] [content]");System.out.println("gcreate [group name] [m1,m2,m3...]");System.out.println("gmembers [group name]");System.out.println("gjoin [group name]");System.out.println("gquit [group name]");System.out.println("quit");System.out.println("==================================");String command = scanner.nextLine();String[] s = command.split(" ");switch (s[0]){case "send":ctx.writeAndFlush(new ChatRequestMessage(username, s[1], s[2]));break;case "gsend":ctx.writeAndFlush(new GroupChatRequestMessage(username, s[1], s[2]));break;case "gcreate":Set<String> set = new HashSet<>(Arrays.asList(s[2].split(",")));set.add(username); // 加入自己ctx.writeAndFlush(new GroupCreateRequestMessage(s[1], set));break;case "gmembers":ctx.writeAndFlush(new GroupMembersRequestMessage(s[1]));break;case "gjoin":ctx.writeAndFlush(new GroupJoinRequestMessage(username, s[1]));break;case "gquit":ctx.writeAndFlush(new GroupQuitRequestMessage(username, s[1]));break;case "quit":ctx.channel().close();return;}}}, "system in").start();}});}});Channel channel = bootstrap.connect("localhost", 8080).sync().channel();channel.closeFuture().sync();} catch (Exception e) {log.error("client error", e);} finally {group.shutdownGracefully();}}
}
3.3 聊天室業(yè)務(wù)-單聊
服務(wù)器端將 handler 獨立出來
登錄 handler
@ChannelHandler.Sharable
public class LoginRequestMessageHandler extends SimpleChannelInboundHandler<LoginRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, LoginRequestMessage msg) throws Exception {String username = msg.getUsername();String password = msg.getPassword();boolean login = UserServiceFactory.getUserService().login(username, password);LoginResponseMessage message;if(login) {SessionFactory.getSession().bind(ctx.channel(), username);message = new LoginResponseMessage(true, "登錄成功");} else {message = new LoginResponseMessage(false, "用戶名或密碼不正確");}ctx.writeAndFlush(message);}
}
單聊 handler
@ChannelHandler.Sharable
public class ChatRequestMessageHandler extends SimpleChannelInboundHandler<ChatRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, ChatRequestMessage msg) throws Exception {String to = msg.getTo();Channel channel = SessionFactory.getSession().getChannel(to);// 在線if(channel != null) {channel.writeAndFlush(new ChatResponseMessage(msg.getFrom(), msg.getContent()));}// 不在線else {ctx.writeAndFlush(new ChatResponseMessage(false, "對方用戶不存在或者不在線"));}}
}
3.4 聊天室業(yè)務(wù)-群聊
創(chuàng)建群聊
@ChannelHandler.Sharable
public class GroupCreateRequestMessageHandler extends SimpleChannelInboundHandler<GroupCreateRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupCreateRequestMessage msg) throws Exception {String groupName = msg.getGroupName();Set<String> members = msg.getMembers();// 群管理器GroupSession groupSession = GroupSessionFactory.getGroupSession();Group group = groupSession.createGroup(groupName, members);if (group == null) {// 發(fā)生成功消息ctx.writeAndFlush(new GroupCreateResponseMessage(true, groupName + "創(chuàng)建成功"));// 發(fā)送拉群消息List<Channel> channels = groupSession.getMembersChannel(groupName);for (Channel channel : channels) {channel.writeAndFlush(new GroupCreateResponseMessage(true, "您已被拉入" + groupName));}} else {ctx.writeAndFlush(new GroupCreateResponseMessage(false, groupName + "已經(jīng)存在"));}}
}
群聊
@ChannelHandler.Sharable
public class GroupChatRequestMessageHandler extends SimpleChannelInboundHandler<GroupChatRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupChatRequestMessage msg) throws Exception {List<Channel> channels = GroupSessionFactory.getGroupSession().getMembersChannel(msg.getGroupName());for (Channel channel : channels) {channel.writeAndFlush(new GroupChatResponseMessage(msg.getFrom(), msg.getContent()));}}
}
加入群聊
@ChannelHandler.Sharable
public class GroupJoinRequestMessageHandler extends SimpleChannelInboundHandler<GroupJoinRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupJoinRequestMessage msg) throws Exception {Group group = GroupSessionFactory.getGroupSession().joinMember(msg.getGroupName(), msg.getUsername());if (group != null) {ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() + "群加入成功"));} else {ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() + "群不存在"));}}
}
退出群聊
@ChannelHandler.Sharable
public class GroupQuitRequestMessageHandler extends SimpleChannelInboundHandler<GroupQuitRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupQuitRequestMessage msg) throws Exception {Group group = GroupSessionFactory.getGroupSession().removeMember(msg.getGroupName(), msg.getUsername());if (group != null) {ctx.writeAndFlush(new GroupJoinResponseMessage(true, "已退出群" + msg.getGroupName()));} else {ctx.writeAndFlush(new GroupJoinResponseMessage(true, msg.getGroupName() + "群不存在"));}}
}
查看成員
@ChannelHandler.Sharable
public class GroupMembersRequestMessageHandler extends SimpleChannelInboundHandler<GroupMembersRequestMessage> {@Overrideprotected void channelRead0(ChannelHandlerContext ctx, GroupMembersRequestMessage msg) throws Exception {Set<String> members = GroupSessionFactory.getGroupSession().getMembers(msg.getGroupName());ctx.writeAndFlush(new GroupMembersResponseMessage(members));}
}
3.5 聊天室業(yè)務(wù)-退出
@Slf4j
@ChannelHandler.Sharable
public class QuitHandler extends ChannelInboundHandlerAdapter {// 當(dāng)連接斷開時觸發(fā) inactive 事件@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {SessionFactory.getSession().unbind(ctx.channel());log.debug("{} 已經(jīng)斷開", ctx.channel());}// 當(dāng)出現(xiàn)異常時觸發(fā)@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {SessionFactory.getSession().unbind(ctx.channel());log.debug("{} 已經(jīng)異常斷開 異常是{}", ctx.channel(), cause.getMessage());}
}
3.6 聊天室業(yè)務(wù)-空閑檢測
連接假死
原因
- 網(wǎng)絡(luò)設(shè)備出現(xiàn)故障，例如網(wǎng)卡，機房等，底層的 TCP 連接已經(jīng)斷開了，但應(yīng)用程序沒有感知到，仍然占用著資源。
- 公網(wǎng)網(wǎng)絡(luò)不穩(wěn)定，出現(xiàn)丟包。如果連續(xù)出現(xiàn)丟包，這時現(xiàn)象就是客戶端數(shù)據(jù)發(fā)不出去，服務(wù)端也一直收不到數(shù)據(jù)，就這么一直耗著
- 應(yīng)用程序線程阻塞，無法進行數(shù)據(jù)讀寫
問題
- 假死的連接占用的資源不能自動釋放
- 向假死的連接發(fā)送數(shù)據(jù)，得到的反饋是發(fā)送超時
服務(wù)器端解決
- 怎么判斷客戶端連接是否假死呢？如果能收到客戶端數(shù)據(jù)，說明沒有假死。因此策略就可以定為，每隔一段時間就檢查這段時間內(nèi)是否接收到客戶端數(shù)據(jù)，沒有就可以判定為連接假死
// 用來判斷是不是 讀空閑時間過長，或 寫空閑時間過長
// 5s 內(nèi)如果沒有收到 channel 的數(shù)據(jù)，會觸發(fā)一個 IdleState#READER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(5, 0, 0));
// ChannelDuplexHandler 可以同時作為入站和出站處理器
ch.pipeline().addLast(new ChannelDuplexHandler() {// 用來觸發(fā)特殊事件@Overridepublic void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception{IdleStateEvent event = (IdleStateEvent) evt;// 觸發(fā)了讀空閑事件if (event.state() == IdleState.READER_IDLE) {log.debug("已經(jīng) 5s 沒有讀到數(shù)據(jù)了");ctx.channel().close();}}
});
客戶端定時心跳
- 客戶端可以定時向服務(wù)器端發(fā)送數(shù)據(jù)，只要這個時間間隔小于服務(wù)器定義的空閑檢測的時間間隔，那么就能防止前面提到的誤判，客戶端可以定義如下心跳處理器
// 用來判斷是不是 讀空閑時間過長，或 寫空閑時間過長
// 3s 內(nèi)如果沒有向服務(wù)器寫數(shù)據(jù)，會觸發(fā)一個 IdleState#WRITER_IDLE 事件
ch.pipeline().addLast(new IdleStateHandler(0, 3, 0));
// ChannelDuplexHandler 可以同時作為入站和出站處理器
ch.pipeline().addLast(new ChannelDuplexHandler() {// 用來觸發(fā)特殊事件@Overridepublic void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception{IdleStateEvent event = (IdleStateEvent) evt;// 觸發(fā)了寫空閑事件if (event.state() == IdleState.WRITER_IDLE) {// log.debug("3s 沒有寫數(shù)據(jù)了，發(fā)送一個心跳包");ctx.writeAndFlush(new PingMessage());}}
});