ElasticSearch三种Java客户端

目录

• 预备知识
• Java客户端分析
• Java API Client
  • Demo
• Java Low Level Rest Client
  • Demo
• Java High Level Rest Client
  • Demo
• 总结

预备知识

官方客户端地址

Java客户端分析

• 分为Java API Client和Java Rest Client
• Java API Client默认连接的是9300端口，传输协议，依赖netty
• Java API Client不同版本有兼容问题
• Java API Client通过方法调用完成交互，有丰富的API
• Java Rest Client默认连接的是9200端口，http协议
• Java Rest Client不同版本没有兼容问题
• Java Rest Client分为High和Low两种
• Java Low Level Rest Client使用Apache HttpClient进行HTTP调用，简单封装了一下，需要自己处理请求和响应，还是面向HTTP请求的，API简单
• Java High Level Rest Client基于Java Low Level Rest Client封装，提供了面向方法的API。同时请求参数和响应参数使用了elasticsearch定义的实体，方便从Java API Client迁移。
• Java High Level Rest Client完成elasticsearch请求响应实体转换为Java Low Level Rest Client的请求响应。即解决了Java API Client兼容问题，又解决了Java Low Level Rest Client封装使用问题

Java API Client

Demo

	<dependency>
		<groupId>org.elasticsearch.client</groupId>
		<artifactId>transport</artifactId>
		<version>7.5.2</version>
	</dependency>

package com.zby;

import java.io.IOException;
import java.net.InetAddress;

import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.TransportAddress;
import org.elasticsearch.transport.client.PreBuiltTransportClient;

/**
 * @author zby
 * @title ElasticSearchApiDemo
 * @date 2020年7月1日
 * @description
 */
@SuppressWarnings({"deprecation", "resource"})
public class ElasticSearchApiDemo {

    public static void main(String[] args) throws IOException {
        TransportClient client = new PreBuiltTransportClient(Settings.EMPTY)
                .addTransportAddress(new TransportAddress(InetAddress.getByName("localhost"), 9300));
        GetResponse response = client.get(new GetRequest("customer", "1")).actionGet();
        System.out.println(response);
        client.close();



    }

}

Java Low Level Rest Client

Demo

	<dependency>
		<groupId>org.elasticsearch.client</groupId>
		<artifactId>elasticsearch-rest-client</artifactId>
		<version>7.5.2</version>
	</dependency>

package com.zby;

import java.io.IOException;

import org.apache.http.HttpHost;
import org.apache.http.util.EntityUtils;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;

/**
 * @author zby
 * @title ElasticSearchLowLevelApiDemo
 * @date 2020年7月1日
 * @description
 */
public class ElasticSearchLowLevelApiDemo {

    public static void main(String[] args) throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200, "http")).build();
        Response response = restClient.performRequest(new Request("GET", "/customer/_doc/1"));
        System.out.println(EntityUtils.toString(response.getEntity()));
        restClient.close();
    }

}

• 请求需要自己组装http请求
• 响应需要自己解析http响应
• 提供了HttpClient对ElasticSearch简单封装

Java High Level Rest Client

Demo

	<dependency>
		<groupId>org.elasticsearch.client</groupId>
		<artifactId>elasticsearch-rest-high-level-client</artifactId>
		<version>7.5.2</version>
	</dependency>

package com.zby;

import java.io.IOException;

import org.apache.http.HttpHost;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;

/**
 * @author zby
 * @title ElasticSearchHighLevelApiDemo
 * @date 2020年7月1日
 * @description
 */
public class ElasticSearchHighLevelApiDemo {

    public static void main(String[] args) throws IOException {
        RestHighLevelClient client =
                new RestHighLevelClient(RestClient.builder(new HttpHost("localhost", 9200, "http")));
        GetResponse getResponse = client.get(new GetRequest("customer", "1"), RequestOptions.DEFAULT);
        System.out.println(getResponse);
        client.close();
    }

}

总结

• Java High Level Rest Client兼顾另外两种api的优点，推荐使用
• Java High Level Rest Client的请求响应跟Java API Client是一样的，但是易用性更好