前面：https://www.cnblogs.com/toov5/p/9899238.html 服務發生宕機 咋辦？

發個事件通知，告知大家喲，

會有通知事件哦

看專案：

服務端：

package com.toov5.zkDubbo;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

import org.I0Itec.zkclient.ZkClient;

//##ServerScoekt服務端
public class ZkServerScoekt implements
 
 Runnable {
    private static int port = 18083;  //socket 服務啟動後的所使用的 埠號

    public static void main(String[] args) throws IOException {
        ZkServerScoekt server = new ZkServerScoekt(port);  //建構函式傳入port
        regServer();  //去zk註冊
        Thread thread = new Thread(server);
        thread.start();
    }

    
 
public ZkServerScoekt(int port) {
        this.port = port;
    }
  //註冊服務
    public static void regServer(){
        //1、建立zk連線
    ZkClient zkClient = new ZkClient("192.168.91.5",5000,10000);
        //2.先建立父節點
    String root = "/toov5";
    if (!zkClient.exists(root)) {
        //如果父節點不存，直接建立父節點
        zkClient.createPersistent(root);  //
 
持久節點
    }
       //3、建立子節點
     String nodeName = root+"/service_"+port;      
     String nodeValue="127.0.0.1:"+port;
     if (zkClient.exists(nodeName)) {  //如果存在 直接刪除掉
        zkClient.delete(nodeName);
    }
     zkClient.createEphemeral(nodeName,nodeValue); //位元組的 臨時節點  如果服務宕機了 找不到了
     System.out.println("服務註冊成功"+nodeName);
     
    }
    
    
    
    public void run() {
        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(port);
            System.out.println("Server start port:" + port);
            Socket socket = null;
            while (true) {
                socket = serverSocket.accept();
                new Thread(new ServerHandler(socket)).start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (serverSocket != null) {
                    serverSocket.close();
                }
            } catch (Exception e2) {

            }
        }
    }

}

客戶端

package com.toov5.zkDubbo;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

import org.I0Itec.zkclient.IZkChildListener;
import org.I0Itec.zkclient.ZkClient;

public class ZkServerClient {
    public static List<String> listServer = new ArrayList<String>();

    public static void main(String[] args) {
        initServer();
        ZkServerClient     client= new ZkServerClient();
        BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            String name;
            try {
                name = console.readLine();
                if ("exit".equals(name)) {
                    System.exit(0);
                }
                client.send(name);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    // 註冊所有server 
    public static void initServer() {
        listServer.clear();
//        listServer.add("127.0.0.1:18080"); //連線服務 放到list中   存放叢集地址 做負載均衡用的   
        //建立zk連線
        final ZkClient zkClient = new ZkClient("192.168.91.5",5000,10000);
        //讀取父節點資訊
       final String root = "/toov5";
        List<String> children=zkClient.getChildren(root);
        for(String pString : children){
            //父+子 =完整的路徑
            String path = root+"/"+pString;
            String nodeValue =zkClient.readData(path);
            //把值放到集合中去
            listServer.add(nodeValue);
        }
        //服務發現成功
         System.out.println("服務發現:"+listServer.toString());
         //然後給 serverCount賦值
         serverCount=listServer.size();
         
         //使用zk事件監聽，如果服務發生宕機情況，重新讀取新的節點
         zkClient.subscribeChildChanges(root, new IZkChildListener() {
            
            public void handleChildChange(String arg0, List<String> children) throws Exception {  //children移除之後 剩下的
                System.out.println("有服務宕機了，重新讀取新的節點資訊"+listServer.toString());
                listServer.clear(); //清除之前的 然後讀取最新的
                for(String pString : children){
                    //父+子 =完整的路徑
                    String path = root+"/"+pString;
                    String nodeValue =zkClient.readData(path);
                    //把值放到集合中去
                    listServer.add(nodeValue);
                }
                serverCount=children.size();
                System.out.println("服務發現"+listServer.toString());
            }
        });
              
    }
    
    
 
  //請求總數
    private static  int  reqCount = 1;
  //服務個數    
    private static int  serverCount = 0; //初始值是0
    
    // 獲取當前server資訊
    public static String getServer() {
//        return listServer.get(0);  不能寫死  本地負載均衡輪詢演算法
    String serverName = listServer.get(reqCount%serverCount );
    System.out.println("客戶端請求次數："+reqCount+"對應伺服器"+serverName);
    reqCount++;
    return serverName;    
    }
    
    public void send(String name) {

        String server = ZkServerClient.getServer();
        String[] cfg = server.split(":"); 

        Socket socket = null;
        BufferedReader in = null;
        PrintWriter out = null;
        try {
            socket = new Socket(cfg[0], Integer.parseInt(cfg[1]));
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(), true);

            out.println(name);
            while (true) {
                String resp = in.readLine();
                if (resp == null)
                    break;
                else if (resp.length() > 0) {
                    System.out.println("Receive : " + resp);
                    break;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (out != null) {
                out.close();
            }
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

pom:

<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">
  <modelVersion>4.0.0</modelVersion>
  <groupId>zkDobbo</groupId>
  <artifactId>com.toov5.zkDubbo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
   <dependencies>
		<dependency>
			<groupId>com.101tec</groupId>
			<artifactId>zkclient</artifactId>
			<version>0.8</version>
		</dependency>
	</dependencies>
</project>

啟動三個服務端，一個客戶端。然後隨機關閉一個服務端：

 控制檯：

當有新節點啟動時候：

 核心部分程式碼欣賞~~