一、快速入門

上面的查詢文檔都是依賴kibana，在瀏覽器頁(yè)面使用DSL語(yǔ)句去查詢es，如何用java去查詢es里面的文檔(數(shù)據(jù))呢
我們通過match_all查詢來(lái)演示基本的API，注意下面演示的是 'match_all查詢，也叫基礎(chǔ)查詢'
首先保證你已經(jīng)做好了 '實(shí)用篇-ES-環(huán)境搭建' ，創(chuàng)建了名為gghotel的索引庫(kù)，然后開始下面的操作。如果需要瀏覽器操作es，那就不需要啟動(dòng)kibana容器

在進(jìn)行下面的操作之前，確保你已經(jīng)看了前面 '實(shí)用篇-ES-RestClient操作文檔' 學(xué)的 '1. RestClient案例準(zhǔn)備'，然后在進(jìn)行下面的操作

第一步: 在src/test/java/cn.itcast.hotel目錄新建HotelSearchTest類，寫入如下

package cn.itcast.hotel;import cn.itcast.hotel.service.IHotelService;
import org.apache.http.HttpHost;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.QueryBuilders;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.io.IOException;@SpringBootTest
public class HotelIndexTest2 {private RestHighLevelClient client;@Autowiredprivate IHotelService hotelService;@Testvoid init(){System.out.println(client);}@BeforeEachvoid setUp(){this.client = new RestHighLevelClient(RestClient.builder(//指定你Centos7部署的es的主機(jī)地址HttpHost.create("http://192.168.229.129:9200")));}@AfterEachvoid tearDown() throws IOException {this.client.close();}@Testvoid testMatchAll() throws IOException {//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)request.source().query(QueryBuilders.matchAllQuery());//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);System.out.println(response);}}

第二步: 把控制臺(tái)里面我們需要的數(shù)據(jù)解析出來(lái)。返回的數(shù)據(jù)很多，我們主要是解析hits里面的數(shù)據(jù)就行了

把HotelSearchTest類修改為如下，主要的修改是sout之前做了一次解析，拿到我們想要的數(shù)據(jù)

package cn.itcast.hotel;import cn.itcast.hotel.pojo.HotelDoc;
import cn.itcast.hotel.service.IHotelService;
import com.alibaba.fastjson.JSON;
import org.apache.http.HttpHost;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;import java.io.IOException;@SpringBootTest
public class HotelIndexTest2 {private RestHighLevelClient client;@Autowiredprivate IHotelService hotelService;@Testvoid init(){System.out.println(client);}@BeforeEachvoid setUp(){this.client = new RestHighLevelClient(RestClient.builder(//指定你Centos7部署的es的主機(jī)地址HttpHost.create("http://192.168.229.129:9200")));}@AfterEachvoid tearDown() throws IOException {this.client.close();}@Testvoid testMatchAll() throws IOException {//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)request.source().query(QueryBuilders.matchAllQuery());//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);//下面為逐層解析json數(shù)據(jù)SearchHits searchHits = response.getHits();long total = searchHits.getTotalHits().value;System.out.println("共有" + total + "條數(shù)據(jù)");SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {String json = hit.getSourceAsString();//反系列化HotelDoc hotelDoc = JSON.parseObject(json, HotelDoc.class);System.out.println("hotelDoc = " + hotelDoc);}}}

二、match的三種查詢

我們剛剛在第一節(jié)演示的是 match_all(也叫基本查詢) 查詢，下面將演示 match(也叫單字段查詢) 和 multi_match(也叫多字段查詢) 查詢

【match 查詢，也叫單字段查詢】

在HotelSearchTest類添加如下

 @Testvoid testMatch() throws IOException {//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)request.source().query(QueryBuilders.matchQuery("name","如家"));//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);//下面為逐層解析json數(shù)據(jù)SearchHits searchHits = response.getHits();long total = searchHits.getTotalHits().value;System.out.println("共有" + total + "條數(shù)據(jù)");SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {String json = hit.getSourceAsString();//反系列化HotelDoc hotelDoc = JSON.parseObject(json, HotelDoc.class);System.out.println("hotelDoc = " + hotelDoc);}}

【multi_match 查詢，也叫多字段查詢】

在HotelSearchTest類添加如下

  @Testvoid testMatch() throws IOException {//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)request.source().query(QueryBuilders.multiMatchQuery("如家","name","business"));//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);//下面為逐層解析json數(shù)據(jù)SearchHits searchHits = response.getHits();long total = searchHits.getTotalHits().value;System.out.println("共有" + total + "條數(shù)據(jù)");SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {String json = hit.getSourceAsString();//反系列化HotelDoc hotelDoc = JSON.parseObject(json, HotelDoc.class);System.out.println("hotelDoc = " + hotelDoc);}}

總結(jié): 要構(gòu)建查詢條件，只要記住一個(gè)QueryBuilders類即可

三、解析代碼的抽取

我們發(fā)現(xiàn)對(duì)于 match、multi_match、match_all 查詢，的解析部分的代碼都是相同的，所以我們可以對(duì)解析部分的代碼進(jìn)行抽取，如下

快捷鍵ctrl + alt + M

  private void handleResponse(SearchResponse response) {//下面為逐層解析json數(shù)據(jù)SearchHits searchHits = response.getHits();long total = searchHits.getTotalHits().value;System.out.println("共有" + total + "條數(shù)據(jù)");SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {String json = hit.getSourceAsString();//反系列化HotelDoc hotelDoc = JSON.parseObject(json, HotelDoc.class);System.out.println("hotelDoc = " + hotelDoc);}}

之后我們?cè)趖est中只專注于json的獲取，解析的任務(wù)交給這段代碼?

四、bool和term、rang精確查詢

原理同上

我們直接演示bool復(fù)合查詢?

?

 @Testvoid testBool() throws IOException {//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)BoolQueryBuilder boolQuery = QueryBuilders.boolQuery();boolQuery.must(QueryBuilders.termQuery("city","杭州"));boolQuery.filter(QueryBuilders.rangeQuery("price").lte(250));request.source().query(boolQuery);//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);handleResponse(response);}

五、排序和分頁(yè)

 @Testvoid testPageAndSort() throws IOException {int pageNum = 1;int pageSize = 5;//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)//查詢所有request.source().query(QueryBuilders.matchAllQuery());//排序request.source().sort("price", SortOrder.ASC);//分頁(yè)request.source().from(pageNum - 1).size(pageSize);//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);handleResponse(response);}

六、高亮顯示

?高亮API包括請(qǐng)求DSL構(gòu)建和結(jié)果解析兩部分，API和對(duì)應(yīng)的DSL語(yǔ)句如下圖，下圖只是構(gòu)建，再下面還有解析，高亮必須由構(gòu)建+解析才能實(shí)現(xiàn)

解析，如下圖?

  @Testvoid testHighLight() throws IOException {//準(zhǔn)備RequestSearchRequest request = new SearchRequest("hotel");//組織DSL參數(shù)//查詢所有request.source().query(QueryBuilders.matchQuery("name","如家"));//設(shè)置高亮匹配方式request.source().highlighter(new HighlightBuilder().field("name").requireFieldMatch(false));//發(fā)送請(qǐng)求，得到響應(yīng)結(jié)果SearchResponse response = client.search(request, RequestOptions.DEFAULT);//下面為逐層解析json數(shù)據(jù)SearchHits searchHits = response.getHits();long total = searchHits.getTotalHits().value;System.out.println("共有" + total + "條數(shù)據(jù)");SearchHit[] hits = searchHits.getHits();for (SearchHit hit : hits) {String json = hit.getSourceAsString();//反系列化HotelDoc hotelDoc = JSON.parseObject(json, HotelDoc.class);//解析，獲取高亮結(jié)果Map<String, HighlightField> highlightFields = hit.getHighlightFields();if(!CollectionUtils.isEmpty(highlightFields)){//根據(jù)字段名獲取高亮結(jié)果HighlightField highlightField = highlightFields.get("name");//判斷高亮字段不為空if(highlightField!=null){//獲取高亮值String name = highlightField.getFragments()[0].string();//覆蓋非高亮結(jié)果hotelDoc.setName(name);}}//最終輸出System.out.println("hotelDoc = " + hotelDoc);}}