ElasticSearch三種Java客戶端

目錄

• 預備知識
• Java客戶端分析
• Java API Client
  • Demo
• Java Low Level Rest Client
  • Demo
• Java High Level Rest Client
  • Demo
• 總結

預備知識

官方客戶端地址

Java客戶端分析

• 分為Java API Client和Java Rest Client
• Java API Client默認連接的是9300端口，傳輸協議，依賴netty
• Java API Client不同版本有兼容問題
• Java API Client通過方法調用完成交互，有豐富的API
• Java Rest Client默認連接的是9200端口，http協議
• Java Rest Client不同版本沒有兼容問題
• Java Rest Client分為High和Low兩種
• Java Low Level Rest Client使用Apache HttpClient進行HTTP調用，簡單封裝了一下，需要自己處理請求和響應，還是面向HTTP請求的，API簡單
• Java High Level Rest Client基於Java Low Level Rest Client封裝，提供了面向方法的API。同時請求參數和響應參數使用了elasticsearch定義的實體，方便從Java API Client遷移。
• Java High Level Rest Client完成elasticsearch請求響應實體轉換為Java Low Level Rest Client的請求響應。即解決了Java API Client兼容問題，又解決了Java Low Level Rest Client封裝使用問題

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();
    }

}

• 請求需要自己組裝http請求
• 響應需要自己解析http響應
• 提供了HttpClient對ElasticSearch簡單封裝

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();
    }

}

總結

• Java High Level Rest Client兼顧另外兩種api的優點，推薦使用
• Java High Level Rest Client的請求響應跟Java API Client是一樣的，但是易用性更好