ElasticSearch client API

从运行结果看并没有打印节点信息出来

从结果看出来，集群节点信道打印出来了，不过这种方法有个问题，就是当我们连接的节点挂掉了，就没法连接整个集群了，这个时候我们就利用他的一个嗅探的功能。

从这里我们可以看到，通过嗅探功能把集群的三个节点都打印出来了

实际上我们只传入master节点，但是同过master节点探测到其他两个节点信息

但是但应用重启之后master节点挂掉了就不能连接集群了，为了防止容错性，我们就多设置几个节点

参考代码ESTestClient.java

 package com.dajiangtai.djt_spider.elasticsearch;

 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.List;

 import org.elasticsearch.client.transport.TransportClient;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.transport.InetSocketTransportAddress;
 import org.junit.Before;
 import org.junit.Test;
 /**
  * 获取TransportClient
  * @author 大讲台
  *
  */
 public class ESTestClient {

     /**
      * 测试使用Java API 连接ElasticSearch 集群
      *
      * @throws UnknownHostException
      */
     @Test
     public void test1() throws UnknownHostException {
         // on startup
         // 获取TransportClient
         TransportClient client = TransportClient
                 .builder()
                 .build()
                 .addTransportAddress(
                         new InetSocketTransportAddress(InetAddress
                                 .getByName("master"), 9300));

         List<DiscoveryNode> connectedNodes = client.connectedNodes();
         for (DiscoveryNode discoveryNode : connectedNodes) {
             System.out.println("集群节点："+discoveryNode.getHostName());
         }
         // on shutdown
         client.close();
     }

     /**
      * 生成环境下，ElasticSearch集群名称非默认需要显示设置
      *
      * @throws UnknownHostException
      */
     @Test
     public void test2() throws UnknownHostException {
         Settings settings = Settings.settingsBuilder()
                 .put("cluster.name", "escluster").build();
         // on startup
         // 获取TransportClient
         TransportClient client = TransportClient
                 .builder()
                 .settings(settings)
                 .build()
                 .addTransportAddress(
                         new InetSocketTransportAddress(InetAddress
                                 .getByName("master"), 9300));

         List<DiscoveryNode> connectedNodes = client.connectedNodes();
         for (DiscoveryNode discoveryNode : connectedNodes) {
             System.out.println("集群节点："+discoveryNode.getHostName());
         }

         // on shutdown
         client.close();
     }

     /**
      * 1、启动应用程序之后，client.transport.sniff能保证即使master挂掉也能连接上集群
      * 2、master节点挂机同时应用程序重启，则无法连接ElasticSearch集群
      *
      * @throws UnknownHostException
      */
     @Test
     public void test3() throws UnknownHostException {

         // 开启client.transport.sniff功能，探测集群所有节点
         Settings settings = Settings.settingsBuilder()
                 .put("cluster.name", "escluster")
                 .put("client.transport.sniff", true).build();
         // on startup
         // 获取TransportClient
         TransportClient client = TransportClient
                 .builder()
                 .settings(settings)
                 .build()
                 .addTransportAddress(
                         new InetSocketTransportAddress(InetAddress
                                 .getByName("master"), 9300));

         List<DiscoveryNode> connectedNodes = client.connectedNodes();
         for (DiscoveryNode discoveryNode : connectedNodes) {
             System.out.println("集群节点："+discoveryNode.getHostName());
         }

         // on shutdown
         client.close();
     }

     /**
      * 1、启动应用程序之后，client.transport.sniff能保证即使master挂掉也能连接上集群
      * 2、设置多节点，防止其中一个节点挂机同时应用程序重启，无法连接ElasticSearch集群问题
      *
      * @throws UnknownHostException
      */
     @Test
     public void test4() throws UnknownHostException {

         // 开启client.transport.sniff功能，探测集群所有节点
         Settings settings = Settings.settingsBuilder()
                 .put("cluster.name", "escluster")
                 .put("client.transport.sniff", true).build();
         // on startup
         // 获取TransportClient
         TransportClient client = TransportClient
                 .builder()
                 .settings(settings)
                 .build()
                 .addTransportAddress(
                         new InetSocketTransportAddress(InetAddress
                                 .getByName("master"), 9300))
                 .addTransportAddress(
                         new InetSocketTransportAddress(InetAddress
                                 .getByName("slave1"), 9300))
                 .addTransportAddress(
                         new InetSocketTransportAddress(InetAddress
                                 .getByName("slave2"), 9300));

         List<DiscoveryNode> connectedNodes = client.connectedNodes();
         for (DiscoveryNode discoveryNode : connectedNodes) {
             System.out.println("集群节点："+discoveryNode.getHostName());
         }

         // on shutdown
         client.close();
     }
 }