zookeeper的Wachter封装

最新推荐文章于 2023-03-01 11:41:34 发布

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最新推荐文章于 2023-03-01 11:41:34 发布

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本文链接：https://blog.youkuaiyun.com/q438944209/article/details/82920443

本文介绍了一个自定义的Zookeeper客户端监听器实现，通过继承Watcher接口并重写process方法来实现节点变化的通知。文章展示了如何创建Zookeeper连接、监听节点创建、数据变更及删除等事件。

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封装一个Watcher的类继承Watcher实现process方法

Watcher是zookeeper的核心方法，其中实现了对节点的监听，zookeeper底层就是数据的存储管理和对数据的监听，其中监听的作用才是其他很多工具使用它的原因。

public class ZkClientWatcher implements Watcher {
	// 集群连接地址，三个用，隔开
	private static final String CONNECT_ADDRES = "192.168.110.159:2181,192.168.110.160:2181,192.168.110.162:2181";
	// 会话超时时间
	private static final int SESSIONTIME = 2000;
	// 信号量,让zk在连接之前等待,连接成功后才能往下走，就是保证主线程在ZK之后结束
	private static final CountDownLatch countDownLatch = new CountDownLatch(1);
	private static String LOG_MAIN = "【main】 ";
	private ZooKeeper zk;

        //创建连接
	public void createConnection(String connectAddres, int sessionTimeOut) {
		try {
			zk = new ZooKeeper(connectAddres, sessionTimeOut, this);
			System.out.println(LOG_MAIN + "zk 开始启动连接服务器....");
			countDownLatch.await();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

        //创建路径和数据，会触发process中的Type=NodeCreated 方法
	public boolean createPath(String path, String data) {
		try {
			this.exists(path, true);
			this.zk.create(path, data.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
			System.out.println(LOG_MAIN + "节点创建成功, Path:" + path + ",data:" + data);
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}

	/**
	 * 判断指定节点是否存在
	 */
	public Stat exists(String path, boolean needWatch) {
		try {
			return this.zk.exists(path, needWatch);
		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

        //更新节点，会触发process中的Type=NodeDataChanged 方法
	public boolean updateNode(String path,String data) throws KeeperException, InterruptedException {
		exists(path, true);
		this.zk.setData(path, data.getBytes(), -1);
		return false;
	}

        //时间监听
	public void process(WatchedEvent watchedEvent) {

		// 获取事件状态
		KeeperState keeperState = watchedEvent.getState();
		// 获取事件类型
		EventType eventType = watchedEvent.getType();
		// zk 路径
		String path = watchedEvent.getPath();
		System.out.println("进入到 process() keeperState:" + keeperState + ", eventType:" + eventType + ", path:" + path);
		// 判断是否建立连接
		if (KeeperState.SyncConnected == keeperState) {
                        //下面判断event的类型，包括增删改并响应事件
			if (EventType.None == eventType) {
				// 如果建立建立成功,让后程序往下走
				System.out.println(LOG_MAIN + "zk 建立连接成功!");
				countDownLatch.countDown();
			} else if (EventType.NodeCreated == eventType) {
                                //节点创建响应事件
				System.out.println(LOG_MAIN + "事件通知,新增node节点" + path);
			} else if (EventType.NodeDataChanged == eventType) {
                                //节点修改响应事件
				System.out.println(LOG_MAIN + "事件通知,当前node节点" + path + "被修改....");
			}
			else if (EventType.NodeDeleted == eventType) {
                                //节点删除响应事件
				System.out.println(LOG_MAIN + "事件通知,当前node节点" + path + "被删除....");
			}
		}
		System.out.println("--------------------------------------------------------");
	}

        //主类进行测试
	public static void main(String[] args) throws KeeperException, InterruptedException {
		ZkClientWatcher zkClientWatcher = new ZkClientWatcher();
		zkClientWatcher.createConnection(CONNECT_ADDRES, SESSIONTIME);
//		boolean createResult = zkClientWatcher.createPath("/p15", "pa-644064");
		zkClientWatcher.updateNode("/pa2","7894561");
	}

}