本地使用Zookeeper偽集群模式钉跷，同步鎖控制多個進(jìn)程的同步狀態(tài)。

1彬坏、獲取鎖

實現(xiàn)方式：
1.各個進(jìn)程創(chuàng)建一個EPHEMERAL_SEQUENTIAL目錄節(jié)點。
2.調(diào)用getChildren方法獲取當(dāng)前的目錄節(jié)點列表中最小的目錄節(jié)點栓始，
  如果是自己創(chuàng)建的血当，那么它就獲得了這個鎖；
  如果不是自己創(chuàng)建的調(diào)用exists()臊旭；并監(jiān)控 Zookeeper 上目錄節(jié)點列表的變化，
  一直到自己創(chuàng)建的節(jié)點是列表中最小編號的目錄節(jié)點就可以獲得鎖离熏。

2、釋放鎖

實現(xiàn)方式：
1.獲取到鎖的Server刪除自己所創(chuàng)建的目錄節(jié)點钻蔑。

3奸鸯、代碼示例

public class MainTest implements Runnable {

    private static ZooKeeper zooKeeper;
    private static String root = "/xmy";
    private static String tempZnode = "/lock";
    private static String myZnode = null;
    private static String hostPort = "127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183";

    public static void main(String[] args) throws Exception {
        zooKeeper = new ZooKeeper(hostPort, 5000, null);
        //創(chuàng)建一個EPHEMERAL_SEQUENTIAL目錄節(jié)點
        myZnode = zooKeeper.create(root + tempZnode, "value".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        System.out.println("----------創(chuàng)建的目錄名為：" + myZnode);

        MainTest mainTest = new MainTest();
        mainTest.tryLock();
    }

    /**
     * 獲取鎖
     */
    public void tryLock() throws Exception {
        System.out.println("----------搶鎖開始----------");

        List<String> list = zooKeeper.getChildren(root, false);
        String[] nodes = list.toArray(new String[list.size()]);
        Arrays.sort(nodes);
        if (myZnode.equals(root + "/" + nodes[0])) {
            System.out.println("----------我搶到了鎖----------");
            Thread.sleep(60 * 1000);
            System.out.println("----------執(zhí)行1分鐘任務(wù)結(jié)束----------");
            doReleaseShared();
        } else {
            waitForLock(nodes[0]);
        }
    }

    void waitForLock(String lower) throws Exception {
        System.out.println("----------未獲取到鎖----------");
        //監(jiān)聽
        Watcher childrenWatcher = new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                System.out.println("----------收到的消息: " + event.toString());
                if (event.getType() == Event.EventType.NodeDeleted) {
                    try {
                        synchronized (this) {
                            notifyAll();
                        }
                    } catch (Exception e) {
                        throw new RuntimeException(e);
                    }
                }
            }
        };
      }

    /**
     * 釋放鎖
     */
    public void doReleaseShared() throws Exception {
        System.out.println("----------我釋放了鎖----------");
        zooKeeper.delete(myZnode, -1);
    }


    @Override
    public void run() {
        try {
            synchronized (this) {
                while (true) {
                    wait();
                }
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
            Thread.currentThread().interrupt();
        } finally {
            this.close();
        }
    }

    public synchronized void close() {
        try {
            zooKeeper.close();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}