zookeeper java API开发服务器动态上下线监控

约定与配置

客户端代码

package com.chen.zk;

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

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

public class DistributeClient {
    private String connectString = "hadoop100:2181,hadoop101:2181,hadoop102:2181";
    private int sessionTimeout = 2000;// 2秒
    private ZooKeeper zooKeeper;

    public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
        DistributeClient client = new DistributeClient();
        //获取连接
        client.getConnect();
        //监听服务器节点的子节点增加和删除
        client.getServer();
        //启动业务逻辑
        client.business();
    }

    private void business() throws InterruptedException {
        Thread.sleep(Long.MAX_VALUE);
    }

    private void getServer() throws KeeperException, InterruptedException {
        List<String> children = zooKeeper.getChildren("/server", true);
        for (String child : children) {
            System.out.println(new String(zooKeeper.getData("/server/" + child, false, null)));
        }
        System.out.println("----------------------");
    }

    private void getConnect() throws IOException {
        zooKeeper = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            //监听
            public void process(WatchedEvent watchedEvent) {
                try {
                    getServer();
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

服务端代码

package com.chen.zk;

import org.apache.zookeeper.*;

import java.io.IOException;

public class DistributeServer {
    private String connectString = "hadoop100:2181,hadoop101:2181,hadoop102:2181";
    private int sessionTimeout = 2000;// 2秒
    private ZooKeeper zooKeeper;

    public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
        DistributeServer server = new DistributeServer();
        //获取连接
        server.getConnect();
        //注册服务器到集群
        server.regist(args[0]);
        //启动业务逻辑
        server.business();
    }

    private void regist(String hostname) throws KeeperException, InterruptedException {
        zooKeeper.create("/server/" + hostname, hostname.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        System.out.println(hostname + " is online");
    }

    private void business() throws InterruptedException {
        Thread.sleep(Long.MAX_VALUE);
    }

    private void getConnect() throws IOException {
        zooKeeper = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            //监听
            public void process(WatchedEvent watchedEvent) {

            }
        });
    }
}