五、ElasticSearch应用
1.ES 的Java API两种方式
Elasticsearch 的API 分为 REST Client API（http请求形式）以及 transportClient
API两种。相比来说transportClient API效率更高，transportClient
是通过Elasticsearch内部RPC的形式进行请求的，连接可以是一个长连接，相当于是把客户端的请求当成
Elasticsearch 集群的一个节点，当然 REST Client API 也支持http
keepAlive形式的长连接，只是非内部RPC形式。但是从Elasticsearch 7 后就会移除transportClient
。主要原因是transportClient 难以向下兼容版本。
1.1 9300[TCP]
利用9300端口的是spring-data-elasticsearch:transport-api.jar,但是这种方式因为对应的SpringBoot版本不一致，造成对应的transport-api.jar也不同，不能适配es的版本，而且ElasticSearch7.x中已经不推荐使用了，ElasticSearch 8之后更是废弃了，所以我们不做过多的介绍
1.2 9200[HTTP]
基于9200端口的方式也有多种
- JsetClient:非官方，更新缓慢
- RestTemplate:模拟发送Http请求，ES很多的操作需要我们自己来封装，效率低
- HttpClient：和上面的情况一样
- ElasticSearch-Rest-Client:官方的RestClient，封装了ES的操作，API层次分明，易于上手。
- JavaAPIClient 7.15版本后推荐
2.ElasticSearch-Rest-Client整合
2.1 创建检索的服务
我们在商城服务中创建一个检索的SpringBoot服务
添加对应的依赖：官方地址：https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-getting-started-maven.html#java-rest-high-getting-started-maven-maven
公共依赖不要忘了，同时我们在公共依赖中依赖了MyBatisPlus所以我们需要在search服务中排除数据源，不然启动报错
然后我们需要把这个服务注册到Nacos注册中心中，这块操作了很多遍，不重复
添加对应的ElasticSearch的配置类
/*** ElasticSearch的配置类*/
@Configuration
public class MallElasticSearchConfiguration {@Beanpublic RestHighLevelClient restHighLevelClient(){RestClientBuilder builder = RestClient.builder(new HttpHost("192.168.56.100", 9200, "http"));RestHighLevelClient client = new RestHighLevelClient(builder);return client;}
}
测试：
2.2 测试保存文档
设置RequestOptions
我们就在ElasticSearch的配置文件中设置
保存数据
然后就可以结合官方文档来实现文档数据的存储
package com.msb.mall.mallsearch;import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.util.JSONPObject;
import com.msb.mall.mallsearch.config.MallElasticSearchConfiguration;
import lombok.Data;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentType;
import org.json.JSONObject;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;@SpringBootTest
class MallSearchApplicationTests {@Autowiredprivate RestHighLevelClient client;@Testvoid contextLoads() {System.out.println("--->"+client);}/*** 测试保存文档*/@Testvoid saveIndex() throws Exception {IndexRequest indexRequest = new IndexRequest("system");indexRequest.id("1");// indexRequest.source("name","bobokaoya","age",18,"gender","男");User user = new User();user.setName("bobo");user.setAge(22);user.setGender("男");// 用Jackson中的对象转json数据ObjectMapper objectMapper = new ObjectMapper();String json = objectMapper.writeValueAsString(user);indexRequest.source(json, XContentType.JSON);// 执行操作IndexResponse index = client.index(indexRequest, MallElasticSearchConfiguration.COMMON_OPTIONS);// 提取有用的返回信息System.out.println(index);}@Dataclass User{private String name;private Integer age;private String gender;}}之后成功
2.3 检索操作
参考官方文档可以获取到处理各种检索情况的API
案例1：检索出所有的bank索引的所有文档
@Testvoid searchIndexAll() throws IOException {// 1.创建一个 SearchRequest 对象SearchRequest searchRequest = new SearchRequest();searchRequest.indices("bank"); // 设置我们要检索的数据对应的索引库SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();/*sourceBuilder.query();sourceBuilder.from();sourceBuilder.size();sourceBuilder.aggregation();*/searchRequest.source(sourceBuilder);// 2.如何执行检索操作SearchResponse response = client.search(searchRequest, MallElasticSearchConfiguration.COMMON_OPTIONS);// 3.获取检索后的响应对象，我们需要解析出我们关心的数据System.out.println("ElasticSearch检索的信息："+response);}
案例2：根据address全文检索
@Testvoid searchIndexByAddress() throws IOException {// 1.创建一个 SearchRequest 对象SearchRequest searchRequest = new SearchRequest();searchRequest.indices("bank"); // 设置我们要检索的数据对应的索引库SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();// 查询出bank下 address 中包含 mill的记录sourceBuilder.query(QueryBuilders.matchQuery("address","mill"));searchRequest.source(sourceBuilder);// System.out.println(searchRequest);// 2.如何执行检索操作SearchResponse response = client.search(searchRequest, MallElasticSearchConfiguration.COMMON_OPTIONS);// 3.获取检索后的响应对象，我们需要解析出我们关心的数据System.out.println("ElasticSearch检索的信息："+response);}
案例3：嵌套的聚合操作：检索出bank下的年龄分布和每个年龄段的平均薪资
/*** 聚合：嵌套聚合* @throws IOException*/@Testvoid searchIndexAggregation() throws IOException {// 1.创建一个 SearchRequest 对象SearchRequest searchRequest = new SearchRequest();searchRequest.indices("bank"); // 设置我们要检索的数据对应的索引库SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();// 查询出bank下 所有的文档sourceBuilder.query(QueryBuilders.matchAllQuery());// 聚合 aggregation// 聚合bank下年龄的分布和每个年龄段的平均薪资AggregationBuilder aggregationBuiler = AggregationBuilders.terms("ageAgg").field("age").size(10);// 嵌套聚合aggregationBuiler.subAggregation(AggregationBuilders.avg("balanceAvg").field("balance"));sourceBuilder.aggregation(aggregationBuiler);sourceBuilder.size(0); // 聚合的时候就不用显示满足条件的文档内容了searchRequest.source(sourceBuilder);System.out.println(sourceBuilder);// 2.如何执行检索操作SearchResponse response = client.search(searchRequest, MallElasticSearchConfiguration.COMMON_OPTIONS);// 3.获取检索后的响应对象，我们需要解析出我们关心的数据System.out.println(response);}
案例4：并行的聚合操作：查询出bank下年龄段的分布和总的平均薪资
/*** 聚合* @throws IOException*/@Testvoid searchIndexAggregation1() throws IOException {// 1.创建一个 SearchRequest 对象SearchRequest searchRequest = new SearchRequest();searchRequest.indices("bank"); // 设置我们要检索的数据对应的索引库SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();// 查询出bank下 所有的文档sourceBuilder.query(QueryBuilders.matchAllQuery());// 聚合 aggregation// 聚合bank下年龄的分布和平均薪资AggregationBuilder aggregationBuiler = AggregationBuilders.terms("ageAgg").field("age").size(10);sourceBuilder.aggregation(aggregationBuiler);// 聚合平均年龄AvgAggregationBuilder balanceAggBuilder = AggregationBuilders.avg("balanceAgg").field("age");sourceBuilder.aggregation(balanceAggBuilder);sourceBuilder.size(0); // 聚合的时候就不用显示满足条件的文档内容了searchRequest.source(sourceBuilder);System.out.println(sourceBuilder);// 2.如何执行检索操作SearchResponse response = client.search(searchRequest, MallElasticSearchConfiguration.COMMON_OPTIONS);// 3.获取检索后的响应对象，我们需要解析出我们关心的数据System.out.println(response);}
案例5：处理检索后的结果
@Testvoid searchIndexResponse() throws IOException {// 1.创建一个 SearchRequest 对象SearchRequest searchRequest = new SearchRequest();searchRequest.indices("bank"); // 设置我们要检索的数据对应的索引库SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();// 查询出bank下 address 中包含 mill的记录sourceBuilder.query(QueryBuilders.matchQuery("address","mill"));searchRequest.source(sourceBuilder);// System.out.println(searchRequest);// 2.如何执行检索操作SearchResponse response = client.search(searchRequest, MallElasticSearchConfiguration.COMMON_OPTIONS);// 3.获取检索后的响应对象，我们需要解析出我们关心的数据// System.out.println("ElasticSearch检索的信息："+response);RestStatus status = response.status();TimeValue took = response.getTook();SearchHits hits = response.getHits();TotalHits totalHits = hits.getTotalHits();TotalHits.Relation relation = totalHits.relation;long value = totalHits.value;float maxScore = hits.getMaxScore(); // 相关性的最高分SearchHit[] hits1 = hits.getHits();for (SearchHit documentFields : hits1) {/*"_index" : "bank","_type" : "account","_id" : "970","_score" : 5.4032025*///documentFields.getIndex(),documentFields.getType(),documentFields.getId(),documentFields.getScore();String json = documentFields.getSourceAsString();//System.out.println(json);// JSON字符串转换为 Object对象ObjectMapper mapper = new ObjectMapper();Account account = mapper.readValue(json, Account.class);System.out.println("account = " + account);}//System.out.println(relation.toString()+"--->" + value + "--->" + status);}@ToString@Datastatic class Account {private int account_number;private int balance;private String firstname;private String lastname;private int age;private String gender;private String address;private String employer;private String email;private String city;private String state;}
数据的结果：
