REST

REST基本介紹

REST (Representational State Transfer), 表現(xiàn)形式狀態(tài)轉(zhuǎn)換(訪問(wèn)網(wǎng)絡(luò)資源的風(fēng)格)

傳統(tǒng)風(fēng)格資源描述形式

• http://localhost/user/getById?id=1
• http://localhost/user/saveUser

REST風(fēng)格描述形式

• http://localhost/user/1
• http://localhost/user

REST優(yōu)點(diǎn):

隱藏資源的訪問(wèn)行為，無(wú)法通過(guò)地址得知對(duì)資源是何種操作

書寫簡(jiǎn)化

REST風(fēng)格介紹:

按照REST風(fēng)格訪問(wèn)資源時(shí)使用行為動(dòng)作區(qū)分對(duì)資源進(jìn)行了何種操作

• http://localhost/users 查詢?nèi)坑脩粜畔?GET（查詢）
• http://localhost/users/1 查詢指定用戶信息 GET（查詢）
• http://localhost/users 添加用戶信息 POST（新增/保存）
• http://localhost/users 修改用戶信息 PUT（修改/更新）
• http://localhost/users/1 刪除用戶信息 DELETE（刪除）

根據(jù)REST風(fēng)格對(duì)資源進(jìn)行訪問(wèn)稱為RESTful

注意事項(xiàng):

上述行為是約定方式，約定不是規(guī)范，可以打破，所以稱REST風(fēng)格，而不是REST規(guī)范

描述模塊的名稱通常使用復(fù)數(shù)，也就是加s的格式描述，表示此類資源，而非單個(gè)資源，例如：users、books、accounts……

RESTful快速入門

1. 設(shè)定http請(qǐng)求動(dòng)作(請(qǐng)求方式)

通過(guò)@RequestMapping注解的, method屬性

@Controller
public class UserController {// 新增/保存 指定請(qǐng)求行為: POST@RequestMapping(value = "/users", method = RequestMethod.POST)@ResponseBodypublic String save(@RequestBody User user) {System.out.println("user save..." + user);return "{'module': 'user save'}";}// 刪除 指定請(qǐng)求行為: DELETE@RequestMapping(value = "/users", method = RequestMethod.DELETE)@ResponseBodypublic String delete(Integer id) {System.out.println("user delete..." + id);return "{'module': 'user delete'}";}
}

2. 設(shè)定請(qǐng)求參數(shù)(路徑變量)

@PathVariable注解, 寫在形參變量的前面, 綁定路徑參數(shù)與處理器方法形參間的關(guān)系，要求路徑參數(shù)名與形參名一一對(duì)應(yīng)

設(shè)置完成后可以在路徑中攜帶id訪問(wèn): http://localhost:80/users/1

@Controller
public class UserController {// 定義路徑參數(shù)@RequestMapping(value = "/users/{id}", method = RequestMethod.DELETE)@ResponseBody// 從路徑參數(shù)中取值public String delete(@PathVariable Integer id) {System.out.println("user delete..." + id);return "{'module': 'user delete'}";}
}

@RequestBody @RequestParam @PathVariable 對(duì)比:

區(qū)別:

@RequestParam用于接收url地址傳參或表單傳參

@RequestBody用于接收json數(shù)據(jù)

@PathVariable用于接收路徑參數(shù)，使用{參數(shù)名稱}描述路徑參數(shù)

應(yīng)用:

后期開發(fā)中，發(fā)送請(qǐng)求參數(shù)超過(guò)1個(gè)時(shí)，以json格式為主，@RequestBody應(yīng)用較廣

如果發(fā)送非json格式數(shù)據(jù)，選用@RequestParam接收請(qǐng)求參數(shù)

采用RESTful進(jìn)行開發(fā)，當(dāng)參數(shù)數(shù)量較少時(shí)，例如1個(gè)，可以采用@PathVariable接收請(qǐng)求路徑變量，通常用于傳遞id值

RESTful快速開發(fā)

使用RESTful開發(fā), 我們可以發(fā)現(xiàn)有許多重復(fù)的代碼

例如下面代碼: 每一個(gè)處理器都需要寫value = "/users"以及@ResponseBody;

@Controller
public class UserController {@RequestMapping(value = "/users", method = RequestMethod.POST)@ResponseBodypublic String save(@RequestBody User user) {System.out.println("user save..." + user);return "{'module': 'user save'}";}@RequestMapping(value = "/users", method = RequestMethod.PUT)@ResponseBodypublic String update(@RequestBody User user) {System.out.println("user update..." + user);return "{'module': 'user update'}";}
}

簡(jiǎn)化一: 將公共的路徑提取到處理器所在類上

@Controller
@RequestMapping("/users")
public class UserController {@RequestMapping(method = RequestMethod.POST)@ResponseBodypublic String save(@RequestBody User user) {System.out.println("user save..." + user);return "{'module': 'user save'}";}@RequestMapping(value = "/{id}", method = RequestMethod.DELETE)@ResponseBodypublic String delete(@PathVariable Integer id) {System.out.println("user delete..." + id);return "{'module': 'user delete'}";}
}

簡(jiǎn)化二: 將每個(gè)處理器都有的@RequestBody注解提取到處理器所在類上

@Controller
@RequestMapping("/users")
@ResponseBody
public class UserController {@RequestMapping(method = RequestMethod.POST)public String save(@RequestBody User user) {System.out.println("user save..." + user);return "{'module': 'user save'}";}@RequestMapping(value = "/{id}", method = RequestMethod.DELETE)public String delete(@PathVariable Integer id) {System.out.println("user delete..." + id);return "{'module': 'user delete'}";}
}

簡(jiǎn)化三: @RestController注解

@RestController等同于@ResponseBody加上@ResponseBody注解組合起來(lái)的功能

@RestController
@RequestMapping("/users")
public class UserController {@RequestMapping(method = RequestMethod.POST)public String save(@RequestBody User user) {System.out.println("user save..." + user);return "{'module': 'user save'}";}@RequestMapping(value = "/{id}", method = RequestMethod.DELETE)public String delete(@PathVariable Integer id) {System.out.println("user delete..." + id);return "{'module': 'user delete'}";}
}

簡(jiǎn)化四: 通過(guò)@GetMapping @PostMapping @PutMapping @DeleteMapping注解替代method = RequestMethod.XXX

設(shè)置當(dāng)前控制器方法請(qǐng)求訪問(wèn)路徑與請(qǐng)求動(dòng)作，每種對(duì)應(yīng)一個(gè)請(qǐng)求動(dòng)作，例如@GetMapping對(duì)應(yīng)GET請(qǐng)求;

默認(rèn)屬性value：請(qǐng)求訪問(wèn)路徑

@RestController
@RequestMapping("/users")
public class UserController {// 新增/保存 指定請(qǐng)求行為: POST@PostMappingpublic String save(@RequestBody User user) {System.out.println("user save..." + user);return "{'module': 'user save'}";}// 刪除 指定請(qǐng)求行為: DELETE@DeleteMapping("/{id}")public String delete(@PathVariable Integer id) {System.out.println("user delete..." + id);return "{'module': 'user delete'}";}// 修改/更新 指定請(qǐng)求行為: PUT@PutMappingpublic String update(@RequestBody User user) {System.out.println("user update..." + user);return "{'module': 'user update'}";}// 查詢?nèi)?指定請(qǐng)求行為: GET@GetMappingpublic String selectAll() {System.out.println("user selectAll...");return "{'module': 'user selectAll'}";}// 查詢根據(jù)id 指定請(qǐng)求行為: GET@GetMapping("/{id}")public String selectById(@PathVariable Integer id) {System.out.println("user selectById..." + id);return "{'module': 'user selectById'}";}
}