一、ElasticSearch介绍
ElasticSearch是一个分布式搜索引擎，能与SpringBoot、Python等框架做集成 , 可扩展性好。 另外elaticsearch官方提供了可视化的图表工具kibana, 能够让您的搜索数据展示的更友好，ElasticSearch提供一系列Rest API给客户端索引, 他能够对海量数据下的指定搜索能快速的做出响应。
官网说明: ElasticSearch是一个基于JSON的分布式搜索和分析引擎。
Spring官网提供了spring data elasticsearch工具包供开发者使用，用SpringBoot开发时，我们一定要注意Springboot版本与ElasticSearch版本对应关系，如果版本对不上，在调用时，可能会发生问题。
elasticsearch与springboot版本对应关系
注: 在ElasticSearch 7以后，Spring data建议采用High-level REST client。
二、Spring Boot 整合ElasticSearch
通过版本关系图，我们需要准备Springboot版本与elasticsearch客户端，我们就使用图中最第一条，即最新版本。
1. SpringBoot版本
Spring Boot 版本采用2.5.6, 可以在2.5.x中选一个即可。
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.5.6</version> <relativePath/> <!-- lookup parent from repository --></parent>
data-elasticsearch不用指定版本，因为是依赖Springboot,Springboot包下载好后，会自定给你指定data-elasticsearch的版本：
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-elasticsearch</artifactId> </dependency>
如上图，maven会自动给你下载4.2.6版本的包，正好也符合Spring官网提供的版本关系图。
其他依赖:
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.5.6</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>org.spring.data</groupId> <artifactId>elasticsearch</artifactId> <version>0.0.1-SNAPSHOT</version> <name>elasticsearch</name> <description>Demo project for Spring Boot</description> <properties> <java.version>11</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.62</version> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> <!-- springboot test--> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <scope>test</scope> </dependency> <!--整合elasticsearch--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-elasticsearch</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>
2. ElasticSearch服务器版本
Spring官网推荐的版本是7.15.2， 在这里推荐一个国内加速下载网站，华为云，地址如下:
Index of elasticsearch-local
下载64位版本:
注: 解压的目录不要放到program files目录下，因为低版本的elasticsearch运行时可能会出现没有权限写入的问题。
解压后到E盘后，启动elasticsearch服务器, 以管理员的身份进行运行:
如果能看到红框框里的内容，说明就启动成功了。
三、调用ElasticSearch
1. 配置elasticSearch客户端
刚提到Spring官网在elasticsearch 7以后，推荐我们使用high-leve-client，那我们就使用RestHighLevelClient。
添加配置类ElasticSearchClientConfig, 可将uri放入到配置文件里，为了方便测试，在这里写固定 http://localhost:9200。
package org.spring.data.config;import org.apache.http.HttpHost;import org.elasticsearch.client.RestClient;import org.elasticsearch.client.RestHighLevelClient;import org.springframework.beans.factory.annotation.Value;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configurationpublic class ElasticSearchClientConfig { @Value("${spring.elasticsearch.rest.uris}") private String urls; @Bean public RestHighLevelClient restHighLevelClient() { RestHighLevelClient restHighLevelClient = new RestHighLevelClient( RestClient.builder( new HttpHost("localhost",9200, "http") ) ); return restHighLevelClient; }}
spring.elasticsearch.rest.uris=http://localhost:9200
2. RestFul API使用
首先引入Springboot test 相关依赖:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope></dependency><dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <scope>test</scope></dependency>
Spring data ElasticSearch提供了的增、删、改、查的包装类, 分别是CreateIndexRequest、DeleteIndexRequest、GetIndexRequest、UpdateRequest，另外不推荐使用过时的API,例如:
@Deprecated public boolean exists(org.elasticsearch.action.admin.indices.get.GetIndexRequest request, RequestOptions options) throws IOException { return (Boolean)this.restHighLevelClient.performRequest(request, IndicesRequestConverters::indicesExist, options, RestHighLevelClient::convertExistsResponse, Collections.emptySet()); }
可以从导包来查看是否过时:org.elasticsearch.action.admin.indices.get, 推荐使用的GetIndexRequest是在org.elasticsearch.client.indices包下。
package org.spring.data;import org.elasticsearch.action.admin.indices.delete.DeleteIndexRequest;import org.elasticsearch.action.support.master.AcknowledgedResponse;import org.elasticsearch.client.RestHighLevelClient;import org.elasticsearch.client.indices.CreateIndexRequest;import org.elasticsearch.client.indices.CreateIndexResponse;import org.elasticsearch.client.indices.GetIndexRequest;import org.junit.jupiter.api.Test;import org.springframework.boot.test.context.SpringBootTest;import org.elasticsearch.client.RequestOptions;import org.springframework.beans.factory.annotation.Autowired;import java.io.IOException;@SpringBootTest(classes = ElasticsearchApplication.class)public class ElasticsearchApplicationTests { @Test void contextLoads() { } @Autowired private RestHighLevelClient restHighLevelClient; /** * create * @throws IOException */ @Test public void testCreateIndex() throws IOException { CreateIndexRequest createIndexRequest = new CreateIndexRequest("test"); CreateIndexResponse response = restHighLevelClient.indices().create(createIndexRequest, RequestOptions.DEFAULT); System.out.println(response); } /** * exist * * @throws IOException */ @Test public void testExistIndex() throws IOException { GetIndexRequest request = new GetIndexRequest("test"); boolean exists = restHighLevelClient.indices().exists(request, RequestOptions.DEFAULT); System.out.println(exists); } /** * delete */ @Test public void deleteIndex() throws IOException { DeleteIndexRequest deleteIndexRequest = new DeleteIndexRequest("test"); AcknowledgedResponse delete = restHighLevelClient.indices().delete(deleteIndexRequest, RequestOptions.DEFAULT); System.out.println(delete.isAcknowledged()); }}
如果都测试成功，那么表示连上了elasticsearch, Spring boot整合elasticsearch成功。
原文:https://juejin.cn/post/7096068549412093983