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这里分类和汇总了欣宸的全部原创(含配套源码)：https://github.com/zq2599/blog_demos
本篇概览
- 本篇是《java与es8实战》系列的第四篇，系列文章写到现在，连个HelloWorld都没运行起来，实在说不过去了...
- 因此，本篇总体目标明确：实战在SpringBoot应用中操作elasticsearch8
- 为了降低难度，本篇部署的elasticsearch8未设置安全检查，无需证书、账号、密码，只要连接到es的IP和端口就能执行操作
- 总体目标可以拆解为两个子任务
- 在SpringBoot中连接elasticsearch8
- 在SpringBoot中使用elasticsearch8官方的Java API Client
- 接下来直接开始
部署elasticsearch集群(无安全检查)
- 关于快速部署elasticsearch集群(无安全检查)，可以参考《docker-compose快速部署elasticsearch-8.x集群+kibana》
Java应用连接elasticsearch的核心套路
- 不论是直连，还是带安全检查的连接，亦或是与SpringBoot的集成使之更方便易用，都紧紧围绕着一个不变的核心套路，该套路由两部分组成，掌握了它们就能在各种条件下成功连接es
- 首先，是builder pattern，连接es有关的代码，各种对象都是其builder对象的build方法创建的，建议您提前阅读《java与es8实战之一》一文，看完后，满屏的builder代码可以从丑变成美...
- 其次，就是java应用能向es发请求的关键：ElasticsearchClient对象，该对象的创建是有套路的，如下图，先创建RestClient，再基于RestClient创建ElasticsearchTransport，最后基于ElasticsearchTransport创建ElasticsearchClient，这是个固定的套路，咱们后面的操作都是基于此的，可能会加一点东西，但不会改变流程和图中的对象
- 准备完毕，开始写代码
新建子工程
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为了便于管理依赖库版本和源码，《java与es8实战》系列的所有代码都以子工程的形式存放在父工程elasticsearch-tutorials中
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《java与es8实战之二：实战前的准备工作》一文说明了创建父工程的详细过程
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在父工程elasticsearch-tutorials中新建名为basic-crud的子工程，其pom.xml内容如下
<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <!-- 请改为自己项目的parent坐标 --> <parent> <artifactId>elasticsearch-tutorials</artifactId> <groupId>com.bolingcavalry</groupId> <version>1.0-SNAPSHOT</version> <relativePath>../pom.xml</relativePath> </parent> <modelVersion>4.0.0</modelVersion> <!-- 请改为自己项目的artifactId --> <artifactId>basic-crud</artifactId> <packaging>jar</packaging> <!-- 请改为自己项目的name --> <name>basic-crud</name> <url>https://github.com/zq2599</url> <!--不用spring-boot-starter-parent作为parent时的配置--> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-dependencies</artifactId> <version>${springboot.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <!-- 不加这个，configuration类中，IDEA总会添加一些提示 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </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>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <!-- exclude junit 4 --> <exclusions> <exclusion> <groupId>junit</groupId> <artifactId>junit</artifactId> </exclusion> </exclusions> </dependency> <!-- junit 5 --> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> <scope>test</scope> </dependency> <!-- elasticsearch引入依赖 start --> <dependency> <groupId>co.elastic.clients</groupId> <artifactId>elasticsearch-java</artifactId> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> </dependency> <!-- 使用spring boot Maven插件时需要添加该依赖 --> <dependency> <groupId>jakarta.json</groupId> <artifactId>jakarta.json-api</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <build> <plugins> <!-- 需要此插件，在执行mvn test命令时才会执行单元测试 --> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>3.0.0-M4</version> <configuration> <skipTests>false</skipTests> </configuration> </plugin> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <excludes> <exclude> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </exclude> </excludes> </configuration> </plugin> </plugins> <resources> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.*</include> </includes> </resource> </resources> </build> </project> 编码：配置文件
- 先准备好配置文件application.yml，内容如下，很简单，只有es的地址信息
elasticsearch: # 多个IP逗号隔开 hosts: 127.0.0.1:9200 编码：配置类
- 首先把启动类写好，平平无奇的启动类BasicCrudApplication.java
@SpringBootApplication public class BasicCrudApplication { public static void main(String[] args) { SpringApplication.run(BasicCrudApplication.class, args); } } - 然后是配置类ClientConfig.java，这是本篇的关键，操作ES所需的ElasticsearchClient实例如何创建，ES的IP地址如何传入，全部写在这里了
package com.bolingcavalry.basic.config; import co.elastic.clients.elasticsearch.ElasticsearchAsyncClient; import co.elastic.clients.elasticsearch.ElasticsearchClient; import co.elastic.clients.json.jackson.JacksonJsonpMapper; import co.elastic.clients.transport.rest_client.RestClientTransport; import lombok.Setter; import org.apache.http.HttpHost; import org.elasticsearch.client.RestClient; import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.util.StringUtils; @ConfigurationProperties(prefix = "elasticsearch") //配置的前缀 @Configuration public class ClientConfig { @Setter private String hosts; /** * 解析配置的字符串，转为HttpHost对象数组 * @return */ private HttpHost[] toHttpHost() { if (!StringUtils.hasLength(hosts)) { throw new RuntimeException("invalid elasticsearch configuration"); } String[] hostArray = hosts.split(","); HttpHost[] httpHosts = new HttpHost[hostArray.length]; HttpHost httpHost; for (int i = 0; i < hostArray.length; i++) { String[] strings = hostArray[i].split(":"); httpHost = new HttpHost(strings[0], Integer.parseInt(strings[1]), "http"); httpHosts[i] = httpHost; } return httpHosts; } @Bean public ElasticsearchClient elasticsearchClient() { HttpHost[] httpHosts = toHttpHost(); RestClient restClient = RestClient.builder(httpHosts).build(); RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper()); return new ElasticsearchClient(transport); } @Bean public ElasticsearchAsyncClient elasticsearchAsyncClient() { HttpHost[] httpHosts = toHttpHost(); RestClient restClient = RestClient.builder(httpHosts).build(); RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper()); return new ElasticsearchAsyncClient(transport); } } - 从上面的代码可以看出，配置类已经向Spring容器注册了ElasticsearchClient实例，后面的业务都可以使用此实例来操作ES
编码：服务类
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本篇只是为了演示SpringBoot应用如何连接和操作ES，还不会深入ES操作的细节，因此只对索引做一些基本操作即可
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先写一个接口IndexService.java，里面定义了多个索引操作的方法
package com.bolingcavalry.basic.service; import co.elastic.clients.elasticsearch._types.mapping.TypeMapping; import co.elastic.clients.elasticsearch.indices.IndexSettings; import co.elastic.clients.util.ObjectBuilder; import java.io.IOException; import java.util.function.Function; public interface IndexService { /** * 新建指定名称的索引 * @param name * @throws IOException */ void addIndex(String name) throws IOException; /** * 检查指定名称的索引是否存在 * @param name * @return * @throws IOException */ boolean indexExists(String name) throws IOException; /** * 删除指定索引 * @param name * @throws IOException */ void delIndex(String name) throws IOException; /** * 创建索引，指定setting和mapping * @param name 索引名称 * @param settingFn 索引参数 * @param mappingFn 索引结构 * @throws IOException */ void create(String name, Function<IndexSettings.Builder, ObjectBuilder<IndexSettings>> settingFn, Function<TypeMapping.Builder, ObjectBuilder<TypeMapping>> mappingFn) throws IOException; } - 然后接口的实现，可见所有操作都是在调用ElasticsearchClient实例的API
package com.bolingcavalry.basic.service.impl; import co.elastic.clients.elasticsearch.ElasticsearchClient; import co.elastic.clients.elasticsearch._types.mapping.TypeMapping; import co.elastic.clients.elasticsearch.indices.IndexSettings; import co.elastic.clients.util.ObjectBuilder; import com.bolingcavalry.basic.service.IndexService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext; import org.springframework.stereotype.Service; import java.io.IOException; import java.util.function.Function; @Service public class IndexServiceImpl implements IndexService { @Autowired private ElasticsearchClient elasticsearchClient; @Override public void addIndex(String name) throws IOException { ApplicationContext applicationContext; elasticsearchClient.indices().create(c -> c.index(name)); } @Override public boolean indexExists(String name) throws IOException { ApplicationContext a; return elasticsearchClient.indices().exists(b -> b.index(name)).value(); } @Override public void delIndex(String name) throws IOException { elasticsearchClient.indices().delete(c -> c.index(name)); } @Override public void create(String name, Function<IndexSettings.Builder, ObjectBuilder<IndexSettings>> settingFn, Function<TypeMapping.Builder, ObjectBuilder<TypeMapping>> mappingFn) throws IOException { elasticsearchClient .indices() .create(c -> c .index(name) .settings(settingFn) .mappings(mappingFn) ); } } - 以上就是本篇的功能代码了，连接ES在其上进行索引相关操作
编码：单元测试
- 为了验证上述代码是否生效，接下来写一个单元测试类IndexServiceTest.java，可以重点关注createIndex方法，里面演示了Builder pattern构建参数的详细步骤
package com.bolingcavalry.basic.service; import co.elastic.clients.elasticsearch._types.mapping.Property; import co.elastic.clients.elasticsearch._types.mapping.TypeMapping; import co.elastic.clients.elasticsearch.indices.IndexSettings; import co.elastic.clients.util.ObjectBuilder; import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.Test; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import java.util.function.Function; @SpringBootTest class IndexServiceTest { @Autowired IndexService indexService; @Test void addIndex() throws Exception { String indexName = "test_index"; Assertions.assertFalse(indexService.indexExists(indexName)); indexService.addIndex(indexName); Assertions.assertTrue(indexService.indexExists(indexName)); indexService.delIndex(indexName); Assertions.assertFalse(indexService.indexExists(indexName)); } @Test void indexExists() throws Exception { indexService.indexExists("a"); } @Test void createIndex() throws Exception { // 索引名 String indexName = "product002"; // 构建setting时，builder用到的lambda Function<IndexSettings.Builder, ObjectBuilder<IndexSettings>> settingFn = sBuilder -> sBuilder .index(iBuilder -> iBuilder // 三个分片 .numberOfShards("3") // 一个副本 .numberOfReplicas("1") ); // 新的索引有三个字段，每个字段都有自己的property，这里依次创建 Property keywordProperty = Property.of(pBuilder -> pBuilder.keyword(kBuilder -> kBuilder.ignoreAbove(256))); Property textProperty = Property.of(pBuilder -> pBuilder.text(tBuilder -> tBuilder)); Property integerProperty = Property.of(pBuilder -> pBuilder.integer(iBuilder -> iBuilder)); // // 构建mapping时，builder用到的lambda Function<TypeMapping.Builder, ObjectBuilder<TypeMapping>> mappingFn = mBuilder -> mBuilder .properties("name", keywordProperty) .properties("description", textProperty) .properties("price", integerProperty); // 创建索引，并且指定了setting和mapping indexService.create(indexName, settingFn, mappingFn); } } - 确保不做安全检查的ES集群运行正常，再执行单元测试，如下图，顺利通过，证明所有对ES的操作都符合预期
- 再用eshead观察product002索引的情况，如下图，三个分片，一个副本，与代码中设置的一致
- 至此最简单的连接和操作ES实战已经完成，希望本篇能给您一些参考，助您顺利完成基本操作
是不是线程安全的
- 官方回应：https://discuss.elastic.co/t/is-elasticsearch-client-is-thread-safe/151745
- 有人在问这个问题，es团队的成员Simon Willnauer的回答是：java的client肯定是线程安全的，golang的不清楚
- 对我来说，有他这话就够了，至于golang的嘛，在本文就不讨论了
源码下载
- 本篇实战的完整源码可在GitHub下载到，地址和链接信息如下表所示(https://github.com/zq2599/blog_demos)
| 名称 | 链接 | 备注 |
|---|---|---|
| 项目主页 | https://github.com/zq2599/blog_demos | 该项目在GitHub上的主页 |
| git仓库地址(https) | https://github.com/zq2599/blog_demos.git | 该项目源码的仓库地址，https协议 |
| git仓库地址(ssh) | git@github.com:zq2599/blog_demos.git | 该项目源码的仓库地址，ssh协议 |
- 这个git项目中有多个文件夹，本次实战的源码在elasticsearch-tutorials文件夹下，如下图红框
- elasticsearch-tutorials是个父工程，里面有多个module，本篇实战的module是basic-crud，如下图红框
