上一篇：Elasticsearch基础与概念
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所有代码均为参考官方文档：官方文档

原文说明

Java 高级 REST 客户端在 Java 低级 REST 客户端之上工作。它的主要目标是公开 API 特定的方法，这些方法接受请求对象作为参数并返回响应对象，以便由客户端自己处理请求编组和响应解组。

每个 API都可以同步或异步调用。同步方法返回一个响应对象，而名称以async后缀结尾的异步方法需要一个侦听器参数，一旦收到响应或错误，就会通知该侦听器参数（在低级客户端管理的线程池上）。

Java High Level REST Client 依赖于 Elasticsearch 核心项目。它接受与相同的请求参数TransportClient并返回相同的响应对象。

java API 文档：JAVA doc
低版本的：Java REST Client
高版本的：Elasticsearch Java API Client

注意安装版本要与客户端引入依赖保持一致，否则会出现版本问题
高版本的初始化方式与低版本的不一样，建议参考对应版本的文档
高版本的依赖会出现一部分jakarta.json加载不到，可引入下面依赖来解决

<dependency>
    <groupId>org.eclipse.parsson</groupId>
    <artifactId>jakarta.json</artifactId>
    <version>1.0.0</version>
</dependency>

Elasticsearch Maven

# 所需的最低 Java 版本是1.8
# 所需依赖
<dependency>
     <groupId>org.elasticsearch.client</groupId>
     <artifactId>elasticsearch-rest-high-level-client</artifactId>
     <version>6.7.2</version>
 </dependency>
 <dependency>
     <groupId>org.elasticsearch</groupId>
     <artifactId>elasticsearch</artifactId>
     <version>6.7.2</version>
 </dependency>

初始化客户端

package com.wdz.es.config.es;

import org.apache.http.HttpHost;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class ElasticsearchConfig {
    @Value("${elasticsearch.hosts}")
    private String hosts;
    @Value("${elasticsearch.username}")
    private String username;
    @Value("${elasticsearch.password}")
    private String password;

    /**
     * 有密码初始化
     *
     * @return
     */
    @Bean(destroyMethod = "close")
    public RestHighLevelClient restHighLevelClient() {
        // 设置密码
        BasicCredentialsProvider provider = new BasicCredentialsProvider();
        provider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username, password));
        RestHighLevelClient restHighLevelClient = new RestHighLevelClient(
                RestClient.builder(setHost()).setHttpClientConfigCallback(
                        new RestClientBuilder.HttpClientConfigCallback() {
                            @Override
                            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpAsyncClientBuilder) {
                                httpAsyncClientBuilder.disableAuthCaching();
                                return httpAsyncClientBuilder.setDefaultCredentialsProvider(provider);
                            }
                        }
                ));
        return restHighLevelClient;
    }

    /**
     * 无密码初始化
     * @return
     */
    @Bean(destroyMethod = "close")
    public RestHighLevelClient restHighLevelClient() {
        RestHighLevelClient restHighLevelClient = new RestHighLevelClient(RestClient.builder(setHost()));
        return restHighLevelClient;
    }

    private HttpHost[] setHost(){
        String[] split = hosts.split(",");
        HttpHost[] hhs = new HttpHost[split.length];
        for (int i = 0; i < split.length; i++) {
            String host = split[i];
            String[] ht = host.split(":");
            hhs[i] = new HttpHost(ht[0], Integer.parseInt(ht[1]), "http");
        }
        return hhs;
    }
}

参数hosts可以多个用户逗号分隔，在代码中进行解析，格式：ip:port

校验和创建索引

/**
 * 校验索引是否存在，如果不存在进行创建
 */
private boolean checkCreate(String index) throws IOException {
    GetIndexRequest request = new GetIndexRequest(index);
    boolean exists = restHighLevelClient.indices().exists(request, RequestOptions.DEFAULT);
    if (!exists) {
        CreateIndexRequest create = new CreateIndexRequest(index);
        CreateIndexResponse createIndexResponse = restHighLevelClient.indices().create(create, RequestOptions.DEFAULT);
        System.out.println(JSONObject.toJSONString(createIndexResponse));
    }
    return exists;
}
// 该方法可以放在业务实现类中，在服务启动时校验一次
@PostConstruct
public void checkCreate(){
   // 索引参数，相当于数据库中的一张表
   String index = "edu-app-user";
   GetIndexRequest request = new GetIndexRequest(index);
   try {
       boolean exists = restHighLevelClient.indices().exists(request, RequestOptions.DEFAULT);
       if (!exists) {
           CreateIndexRequest create = new CreateIndexRequest(index);
           CreateIndexResponse createIndexResponse = restHighLevelClient.indices().create(create, RequestOptions.DEFAULT);
           System.out.println(JSONObject.toJSONString(createIndexResponse));
       }
   } catch (IOException e) {
       e.printStackTrace();
   }
}

同步添加数据

为了方便调试，所有接口使用get方式

# 方式一：使用map方式进行添加数据，推荐使用
@GetMapping("add")
public IndexResponse add(String id, String name, String mobile, Integer age) {
    Map<String, Object> jsonMap = new HashMap<>();
    jsonMap.put("id", id);
    jsonMap.put("name", name);
    jsonMap.put("mobile", mobile);
    jsonMap.put("age", age);
    // 参数1: 索引，同一个文档（或者说数据库中的表名）唯一，
    // 参数2：文档类型，在高版本中已经优化，可不需要该参数，
    // 参数3：id,内部id参数值，也可默认,该参数是String类型
    IndexRequest request = new IndexRequest("edu-app-user", "doc", id).source(jsonMap);
    // 选填数据
    request.opType(DocWriteRequest.OpType.CREATE);
    IndexResponse response = null;
    try {
        // 校验索引是否存在，否则
        checkCreate("edu-app-user");
        // 执行添加，默认的请求操作方式
        response = restHighLevelClient.index(request, RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return response;
}

# 方式二 拼接json方式，该方式不推荐使用，容易出错
@GetMapping("add2")
public IndexResponse add2(String id, String name, String mobile, Integer age) {
    IndexRequest request = new IndexRequest("edu-app-user", "doc", id);
    String jsonString = "{" +
                "\"id\":" + id + "," +
                "\"name\":" + name + "," +
                "\"mobile\":" + mobile + "," +
                "\"age\":" + age +
                "}";
    request.source(jsonString, XContentType.JSON.mediaType());
    IndexResponse response = null;
    try {
        response = restHighLevelClient.index(request, RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return response;
}
# XContentType 中定义多种类型，默认是XContentType.JSON = "application/json",会出现编码问题

# 方式三 推荐使用，更简洁易读
@GetMapping("add3")
public IndexResponse add3(String id, String name, String mobile, Integer age) throws IOException {
    XContentBuilder builder = XContentFactory.jsonBuilder();
    builder.startObject();
    {
        builder.field("id", id);
        builder.field("name", name);
        builder.field("mobile", mobile);
        builder.timeField("updateTime", new Date());
        builder.field("age", age);
    }
    builder.endObject();
    IndexRequest request = new IndexRequest("edu-app-user", "doc", id);
    request.source(builder);
    IndexResponse response = null;
    try {
        response = restHighLevelClient.index(request, RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return response;
}

# 方式四：直接在request.source()中进行参数操作
@GetMapping("add4")
public IndexResponse add4(String id, String name, String mobile, Integer age) {
    IndexRequest request = new IndexRequest("edu-app-user", "doc", id)
            .source("id", id,
                    "name", name,
                    "age", age,
                    "mobile", mobile);
    IndexResponse response = null;
    try {
        response = restHighLevelClient.index(request, RequestOptions.DEFAULT);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return response;
}

# 其他可选方法
# 过期时间指定，两种方式
request.timeout(TimeValue.timeValueSeconds(1)); 
request.timeout("1s");
# 刷新策略
request.setRefreshPolicy(WriteRequest.RefreshPolicy.WAIT_UNTIL); 
request.setRefreshPolicy("wait_for");  

异步添加数据

同步与异步区别是方法上：(springboot 中的es版本和显式引入的依赖会出现冲突问题，直接显式定义es版本即可解决)

<properties>
   <elasticsearch.version>6.7.2</elasticsearch.version>
</properties>

@GetMapping("addAsync")
public void addAsync(String id, String name, String mobile, Integer age) {
     IndexRequest request = new IndexRequest("edu-app-user", "doc", id)
             .source("id", id,
                     "name", name,
                     "age", age,
                     "mobile", mobile);
     restHighLevelClient.indexAsync(request, RequestOptions.DEFAULT, new EduAppUserListener());
 }

# 监听类
package com.wdz.es.config.es;

import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.index.IndexResponse;

public class EduAppUserListener implements ActionListener<IndexResponse> {
    @Override
    public void onResponse(IndexResponse response) {
        System.out.println("异步保存成功："+ response);
    }

    @Override
    public void onFailure(Exception e) {
        System.out.println("异步保存失败："+ e.getMessage());
    }
}

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