06_zookeeper原生Java API使用

/**
     * 客户端和zk服务端的连接是一个异步的过程
     * 当连接成功后，客户端会收到一个watch通知
     *
     * ZooKeeper(String connectString, int sessionTimeout, Watcher watcher,
     *          long sessionId, byte[] sessionPasswd, boolean canBeReadOnly)
     * 参数介绍
     * connectString：连接服务器的ip字符串
     *      比如："192.168.1.1:2181,192.168.1.2:2181,192.168.1.3:2181"
     *      可以是一个ip，也可以是多个ip，一个ip代表单机，多个ip代表集群
     *      也可以在ip后加路径
     * sessionTimeout：超时时间，心跳收不到了，那就超时
     * watcher：通知事件，如果有对应的事件触发，则会收到一个通知：如果不需要，那就设为null
     * sessionId：会话的id
     * sessionPasswd：会话密码，当会话丢失后，可以依据sessionId和sessionPasswd重新获取会话
     * canBeReadOnly：可读，当这个物理机节点断开后，还是可以读到数据的，只是不能写，
     *                此时数据被读取到的可能是旧数据，一般设置为false，不推荐使用
     *
     */
public ZooKeeper(String connectString, int sessionTimeout, Watcher watcher, long sessionId, byte[] sessionPasswd, boolean canBeReadOnly)

package com.zk.demo;

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

/**
 * Created by HigginCui on 2018/9/20.
 */
public class ZkConnect implements Watcher{

    public static final String zkServerPath = "127.0.0.1:2181";

    public static final Integer timeout = 5000;

    /**
     * 客户端和zk服务端的连接是一个异步的过程
     * 当连接成功后，客户端会收到一个watch通知
     */
    public static void main(String[] args) throws Exception{
        ZooKeeper zk = new ZooKeeper(zkServerPath,timeout,new ZkConnect());

        for (int i=0;i<20;i++) {
            Thread.sleep(10);  //休眠10ms，在这个过程中，连接状态会从CONNECTING--->CONNECTED
            System.out.println(i+"---"+zk.getState());
        }

    }

    @Override
    public void process(WatchedEvent watchedEvent) {
        System.err.println("收到zk的watch通知----" );
    }
}

package com.zk.demo;

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

import java.util.concurrent.CountDownLatch;

public class ZkConnect implements Watcher{

    public static final String zkServerPath = "127.0.0.1:2181";

    public static final Integer timeout = 5000;

    private static CountDownLatch latch = new CountDownLatch(1);

    public static void main(String[] args) throws Exception{
        ZooKeeper zk = new ZooKeeper(zkServerPath,timeout,new ZkConnect());

        System.out.println("连接状态---" + zk.getState());
        latch.await();
        System.out.println("连接状态---" + zk.getState());

    }

    @Override
    public void process(WatchedEvent watchedEvent) {
        System.err.println("收到zk的watch通知----" );
        latch.countDown();
    }
}