zookeeper分布式锁用法

package com.example.demo3.zk;

import lombok.extern.slf4j.Slf4j;
import org.apache.storm.shade.org.apache.zookeeper.*;
import java.util.concurrent.CountDownLatch;

/**
 * Zookeeper 初始化，获取锁，释放锁。创建临时锁。
 */
@Slf4j
public class ZooKeeperSession {

    private static CountDownLatch countDownLatch=new CountDownLatch(1);

    private ZooKeeper zooKeeper;

    //目录
    private String lockPath="/orderId-lock-";

    /**
     * 连接zookeeper
     */
    public ZooKeeperSession(){
        try {
            //连接zk服务器
            this.zooKeeper=new ZooKeeper("192.168.132.154:2181,192.168.132.156:2181,192.168.132.155:2181",
                    50000,new ZooKeeperWatcher());
            log.info("状态："+zooKeeper.getState().toString());

            try {
                countDownLatch.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        log.info("ZooKeeper session 建立......");
    }

    /**
     * 获取分布式锁。
     * @param orderId
     */
    public void acquireDistributeLock(Long orderId) {
        String path = lockPath + orderId;
        try {
            zooKeeper.create(path, "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
            log.info("success to acquire lock for order[id=" + orderId + "]");
        } catch (Exception e) {
            e.printStackTrace();
            int count = 0;
            while (true) {
                try {
                    Thread.sleep(20);
                    zooKeeper.create(path, "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

                } catch (Exception e1) {
                    e1.printStackTrace();
                    count++;
                    continue;
                }
                log.info("success to acquire lock for order[id=" + orderId + " after " + count + " times try......");
                break;
            }
        }
    }

    /**
     * 释放分布式锁。
     * @param orderId
     */
    public void releaseDistributeLock(Long orderId){
        String path = lockPath+orderId;
        try {
            zooKeeper.delete(path,-1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (KeeperException e) {
            e.printStackTrace();
        }
    }

    private class ZooKeeperWatcher implements Watcher{

        @Override
        public void process(WatchedEvent event) {
            log.info("Receive watch event:"+event.getState());
            if(Event.KeeperState.SyncConnected == event.getState()){
                countDownLatch.countDown();
            }
        }
    }

    /**
     * 封装单例静态内部类。
     */
    private static class Singleton{
        private static ZooKeeperSession instance;

        static {
            instance=new ZooKeeperSession();
        }

        public static ZooKeeperSession getIntance(){
            return instance;
        }
    }

    /**
     * 获取单例。
     * @return
     */
    public static ZooKeeperSession getInstance(){
        return Singleton.getIntance();
    }

    /**
     * 初始化单例方法。
     */
    public static void init(){
        getInstance();
    }
}

package com.example.demo3;

import com.example.demo3.zk.ZooKeeperSession;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;

@Slf4j
public class TestZooKeeper extends Demo3ApplicationTests {

    /**
     * 测试分布式锁。
     */
    @Test
    public void testZookeeper() {
        Long orderId = 1L;
        ZooKeeperSession zooKeeperSession = new ZooKeeperSession();
        log.info("获取锁");
        zooKeeperSession.acquireDistributeLock(orderId);
        log.info("执行业务逻辑...");
        zooKeeperSession.releaseDistributeLock(orderId);
        log.info("释放锁");
    }

}