1.zookeeper的watches
1）可以理解为一个监听，ZooKeeper中的所有读取操作 - getData（），getChildren（）和exists（） - 都可以设置选择监视
2）watches的范围
创建事件,删除事件,更改事件,子事件
3）删除watches
我们可以通过调用removeWatches删除在znode上注册的手表
2.watches样例(java)
public class ZKDemo implements Watcher {
private static CountDownLatch countDownLatch = new CountDownLatch(1);
private static ZooKeeper zooKeeper;
public static void main(String[] args) throws Exception {
connetionZK("");
close();
}
public static void connetionZK(String zk) throws IOException, KeeperException, InterruptedException {
//zookeeper的ip:端口
String path = "192.168.10.150:2181";
zooKeeper = new ZooKeeper(path, 20*1000, new ZKDemo());
//创建节点并给值
// createZnode(zooKeeper, "/test", "test1".getBytes());
//子节点列表更改
// createZnodeChild(zooKeeper, "/test", "test2".getBytes());
//修改节点数据
// createZnodeAndChanged(zooKeeper, "/test", "test3".getBytes());
//创建并删除节点
// createZnodeAndDelete(zooKeeper, "/test", "test4".getBytes());
//数据节点下删除watch
// createZnodeAndRMDataWatch(zooKeeper, "/test", "test5".getBytes());
//子节点下删除watch
// createZnodeAndRMChildWatch(zooKeeper, "/test", "test6".getBytes());
countDownLatch.await();//阻塞程序继续执行
}
/**
* 创建节点并给值
* @param zooKeeper
* @param path
* @param data
*/
public static void createZnode(ZooKeeper zooKeeper,String path,byte [] data) {
//创建节点 路径,节点值,Watch,类型
try {
zooKeeper.exists(path, true);//使用默认的watcher,这里的默认指new ZooKeeper(path, 20*1000, new ZKDemo())时设置的watcher
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 子节点列表更改
* @param zooKeeper
* @param path
* @param data
*/
public static void createZnodeChild(ZooKeeper zooKeeper,String path,byte [] data) {
//创建节点 路径,节点值,Watch,类型
try {
zooKeeper.exists(path, true);//使用默认的watcher,这里的默认指new ZooKeeper(path, 20*1000, new ZKDemo())时设置的watcher
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
zooKeeper.getChildren(path, true);
zooKeeper.create(path+"/child1", "child".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 修改节点数据
* @param zooKeeper
* @param path
* @param data
*/
public static void createZnodeAndChanged(ZooKeeper zooKeeper,String path,byte [] data) {
//创建节点 路径,节点值,Watch,类型
try {
zooKeeper.exists(path, true);//使用默认的watcher,这里的默认指new ZooKeeper(path, 20*1000, new ZKDemo())时设置的watcher
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
zooKeeper.exists(path, true);
zooKeeper.setData(path, "Changed".getBytes(), -1);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 创建并删除节点
* @param zooKeeper
* @param path
* @param data
*/
public static void createZnodeAndDelete(ZooKeeper zooKeeper,String path,byte [] data) {
//创建节点 路径,节点值,Watch,类型
try {
zooKeeper.exists(path, true);//使用默认的watcher,这里的默认指new ZooKeeper(path, 20*1000, new ZKDemo())时设置的watcher
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
zooKeeper.exists(path, true);
zooKeeper.delete(path, -1);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 数据节点下删除watch
* @param zooKeeper
* @param path
* @param data
*/
public static void createZnodeAndRMDataWatch(ZooKeeper zooKeeper,String path,byte [] data) {
//创建节点 路径,节点值,Watch,类型
try {
zooKeeper.exists(path, true);//使用默认的watcher,这里的默认指new ZooKeeper(path, 20*1000, new ZKDemo())时设置的watcher
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
zooKeeper.setData(path, "watch1".getBytes(), -1);
ZKDemo zkDemo = new ZKDemo();
byte[] bytes = zooKeeper.getData(path, zkDemo, new Stat());
System.out.println(new String(bytes));
zooKeeper.removeWatches(path, zkDemo, WatcherType.Data, true);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 子节点下删除watch
* @param zooKeeper
* @param path
* @param data
*/
public static void createZnodeAndRMChildWatch(ZooKeeper zooKeeper,String path,byte [] data) {
//创建节点 路径,节点值,Watch,类型
try {
ZKDemo zkDemo = new ZKDemo();
zooKeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
zooKeeper.create(path+"/child2", "child2".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);//
zooKeeper.setData(path, data, -1);
zooKeeper.getChildren(path, zkDemo);
zooKeeper.removeWatches(path, zkDemo, WatcherType.Children, true);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* 关闭zk
*/
public static void close() {
try {
if (zooKeeper != null) {
zooKeeper.close();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void process(WatchedEvent event) {
countDownLatch.countDown();
if (Event.KeeperState.SyncConnected == event.getState()) {//连接状态
System.out.println("连接状态");
} else if (Event.KeeperState.Disconnected == event.getState()) {//断开状态
System.out.println("断开zookeeper");
} else if (Event.KeeperState.AuthFailed == event.getState()) {//身份验证失败
System.out.println("身份验证失败");
} else if (Event.KeeperState.ConnectedReadOnly == event.getState()) {//连接只读状态
System.out.println("连接只读状态");
} else if (Event.KeeperState.SaslAuthenticated == event.getState()) {//sasl授权权限执行ZooKeeper操作
System.out.println("sasl授权权限执行ZooKeeper操作");
} else if (Event.KeeperState.Expired == event.getState()) {//服务器失效
System.out.println("服务器失效");
} else if (Event.KeeperState.Closed == event.getState()) {//客户端关闭
System.out.println("客户端关闭");
} else {
System.out.println("未知");
}
System.out.println("**************************************");
if (Event.EventType.None == event.getType()) {
System.out.println(event.getType());
} else if (Event.EventType.NodeCreated == event.getType()) {
System.out.println(event.getType());
} else if (Event.EventType.NodeDeleted == event.getType()) {
System.out.println(event.getType());
} else if (Event.EventType.NodeDataChanged == event.getType()) {
System.out.println(event.getType());
} else if (Event.EventType.NodeChildrenChanged == event.getType()) {
System.out.println(event.getType());
} else if (Event.EventType.DataWatchRemoved == event.getType()) {
System.out.println(event.getType());
} else if (Event.EventType.ChildWatchRemoved == event.getType()) {
System.out.println(event.getType());
} else {
System.out.println("未知");
}
System.out.println("######################################");
}
}