实现过程：

首先，一个线程获取锁并调用方法生成订单号，在该线程未释放锁资源时，其他线程会被

countDownLatch阻塞，直到该线程释放锁资源。

实现模拟并发生成订单号功能

代码实现：

先导入一个依赖

        <dependency>
            <groupId>com.101tec</groupId>
            <artifactId>zkclient</artifactId>
            <version>0.10</version>
        </dependency>

Lock接口：

package com.doll.zookeeperlock;

public interface Lock {
    /**
     * 获取锁
     */
    void getLock();

    /**
     * 释放锁
     */
    void unLock();
}

ZookeeperAbstractLock抽象类并实现Lock

package com.doll.zookeeperlock;

import org.I0Itec.zkclient.ZkClient;

import java.util.concurrent.CountDownLatch;

public abstract class ZookeeperAbstractLock implements Lock{

    private static final String CONNECTSTRING="linuxIP地址:zookeeper端口"; // zookeeper地址

    protected ZkClient zkClient=new ZkClient(CONNECTSTRING); // 连接zookeeper

    protected static String PATH="/lock"; // 创建节点路径

    protected CountDownLatch countDownLatch; // 倒计时器作用线程阻塞

    @Override
    public void getLock() {
        if(tryLock()){
            System.out.println("---------------获取锁成功---------------");
        }else {
            waitLock();
            getLock(); //自己调自己
        }
    }

    @Override
    public void unLock() {
        if(zkClient!=null){
            zkClient.close();
            System.out.println("---------------释放资源---------------");
        }
    }

    /**
     * 是否获取锁成功
     * @return
     */
    public abstract boolean tryLock();

    /**
     * 等待锁
     */
    public abstract void waitLock();
}

OrderNumGenerator订单号生成类：

package com.doll.zookeeperlock;

import java.text.SimpleDateFormat;
import java.util.Date;

public class OrderNumGenerator {

    //组成订单号的变量
    private static int count = 0;

    /**
     * 使用new Date()和count生成订单号
     * @return
     */
    public String getNumber() {
        SimpleDateFormat simpt = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss"); //时间类型转化
        return simpt.format(new Date()) + "-" + ++count;
    }

}

ZookeeperDistrbuteLock继承并实现分布式锁

package com.doll.zookeeperlock;

import org.I0Itec.zkclient.IZkDataListener;

import java.util.concurrent.CountDownLatch;


public class ZookeeperDistrbuteLock extends ZookeeperAbstractLock {

    public boolean tryLock() {
        try {
            //创建临时节点成功，返回true
            zkClient.createEphemeral(PATH);
            return true;
        } catch (Exception e) {
            return false;
        }
    }

    public void waitLock() {
        // 使用事件监听，获取到节点被删除
        IZkDataListener iZkDataListener = new IZkDataListener(){
            public void handleDataChange(String s, Object o) throws Exception {

            }

            public void handleDataDeleted(String s) throws Exception {
                if(countDownLatch!=null){
                    countDownLatch.countDown();
                }
            }
        };

        zkClient.subscribeDataChanges(PATH,iZkDataListener);
        if(zkClient.exists(PATH)){
            countDownLatch=new CountDownLatch(1);
            try {
                countDownLatch.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        zkClient.unsubscribeDataChanges(PATH,iZkDataListener);
    }
}

OrderService，main方法类

package com.doll.zookeeperlock;

//Runnable模拟并发编程
public class OrderService implements Runnable {

    private OrderNumGenerator orderNumGenerator = new OrderNumGenerator();

    private Lock lock = new com.doll.zookeeperlock.ZookeeperDistrbuteLock();

    public void run() {
        try {
            lock.getLock();
            getNumber();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unLock();
        }
    }


    public void getNumber(){
        String orderNo = orderNumGenerator.getNumber();
        System.out.println(Thread.currentThread().getName() + ",orderNo=======>:" + orderNo);
    }


    public static void main(String[] args) {
        System.out.println("--------------模拟生成订单号开始--------------");
        for (int i = 1; i <10 ; i++) {
            new Thread(new OrderService()).start();
        }
    }
}

运行结果图