ElasticSearch进阶篇之ElasticSearch-Rest-Client在SpringBoot项目中实战

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 { @Bean public RestHighLevelClient restHighLevelClient(){ RestClientBuilder builder = RestClient.builder(new HttpHost("192.168.56.100", 9200, "http")); RestHighLevelClient client = new RestHighLevelClient(builder); return client; } }

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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 { @Autowired private RestHighLevelClient client; @Test void contextLoads() { System.out.println("--->"+client); } /** * 测试保存文档 */ @Test void 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); } @Data class User{ private String name; private Integer age; private String gender; } }

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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

@Test void 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); }

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案例2：根据address全文检索

@Test void 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); }

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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 */ @Test void 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); }

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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 */ @Test void 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); }

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案例5：处理检索后的结果

@Test void 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 @Data static 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; }

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数据的结果：

Elasticsearch Spring Boot

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