1．需求

2．需求分析，如圖 5-12 所示

3．具體實現

[zk: localhost:2181(CONNECTED) 10] create /servers "servers"
Created /servers

package com.atguigu.zkclient;

import java.io.IOException;

import org.apache.zookeeper.CreateMode;
 
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.ZooDefs.Ids;

public class DistributeServer {
    private static final String CONNECTION_STRING = "192.168.1.122:2181,192.168.1.133:2181,192.168.1.144:2128";
    
 
private static final int SESSION_TIMEOUT = 300000;
    private ZooKeeper zk;
    private String parentNode = "/servers";

    // 建立到 zk 的客戶端連線
    public void getConnect() throws IOException {
        zk = new ZooKeeper(CONNECTION_STRING, SESSION_TIMEOUT, new Watcher() {

            @Override
            public
 
 void process(WatchedEvent evemt){
            }
        });
    }
    
    // 註冊伺服器
    public void registerServer(String hostname) throws Exception {
        String create = zk.create(parentNode+"/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        System.out.println(hostname + " is online "+ create);
    }


    // 業務功能
    public void business(String hostname) throws Exception{
        System.out.println(hostname + "is working ...");
        Thread.sleep(Long.MAX_VALUE)

    }

    public static void main(String[] args) throws Exception{
        // 1 獲取 zk 連線
        DistributeServer server = new DistributeServer();
        server.getConnect();

        // 2 利用 zk 連線註冊伺服器資訊
        server.registerServer(args[0]);

        // 3 啟動業務功能
        server.business(args[0]);
    }
}

package com.atguigu.zkclient;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

public class DistributeClient {
    private static final String CONNECTION_STRING = "192.168.1.122:2181,192.168.1.133:2181,192.168.1.144:2128";
    private static final int SESSION_TIMEOUT = 300000;
    private ZooKeeper zk;
    private String parentNode = "/servers";

    // 建立到 zk 的客戶端連線
    public void getConnect() throws IOException {
        zk = new ZooKeeper(CONNECTION_STRING, SESSION_TIMEOUT, new Watcher() {
            public void process(WatchedEvent event){
                try {
                    getServerList();
                } catch (Exception e) {
                    //TODO: handle exception
                    e.printStackTrace();
                }
            }
        });
    }

    // 獲取伺服器列表資訊
    public void getServerList() throws Exception {
        // 1 獲取伺服器子節點資訊，並且對父節點進行監聽
        List<String> children = zk.getChildren(parentNode, true);

        // 2 儲存伺服器資訊列表
        ArrayList<String> servers = new ArrayList<>();

        // 3 遍歷所有節點，獲取節點中的主機名稱資訊
        for (String child : children) {
            byte[] data = zk.getData(parentNode + "/" + child, false, null);
            servers.add(new String(data));
        }

        // 4 列印伺服器列表資訊
        System.out.println(servers);
    }

    // 業務功能
    public void business() throws Exception {
        System.out.println("client is working ....");
        Thread.sleep(Long.MAX_VALUE);
    }

    public static void main(String[] args) throws Exception{
        // 1 獲取 zk 連線
        DistributeClient client = new DistributeClient();
        client.getConnect();

        // 2 獲取 servers 的子節點資訊，從中獲取伺服器資訊列表
        client.getServerList();

        // 3 業務程序啟動
        client.business();
    }
}