zk

1.连接对象创建

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public static void main(String[] args) {     CuratorFramework ct = CuratorFrameworkFactory.builder()             //ip:端口             .connectString("192.168.10.132:2181,192.168.10.133:2181,192.168.10.135:2181")//连接集群             //超时时间             .sessionTimeoutMs(5000)             //连接断开5秒后，会进行一次重连             .retryPolicy(new RetryOneTime(5000))             //命名空间，该命名空间作为父节点             .namespace("ct").build();     //打开连接     ct.start();     //是否连接成功     System.out.println(ct.isStarted());     //关闭连接     ct.close(); }

　　

重连策略：

RetryOneTime(int sleepMsBetweenRetry)：只重连一次

RetryNTimes(int n, int sleepMsBetweenRetries)：重连n次

RetryUntilElapsed(int maxElapsedTimeMs, int sleepMsBetweenRetries)：每sleepMsBetweenRetries毫秒重连一次，总等待时间超过maxElapsedTimeMs毫秒后停止重连

ExponentialBackoffRetry(int baseSleepTimeMs, int maxRetries)：重连maxRetries次，重连间隔基于baseSleepTimeMs计算
计算公式如下：baseSleepTimeMs*Math.max(1,random.nextInt(1<<(retryCount+1)))。

2.创建节点

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ct.create()         //节点类型         .withMode(CreateMode.PERSISTENT)         //节点权限         .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)         //节点路径和数据         .forPath("/node1","node1".getBytes());   支持递归创建节点 ct.create()         //父节点不存在则创建         .creatingParentsIfNeeded()         //节点类型         .withMode(CreateMode.PERSISTENT)         //节点权限         .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)         //节点路径和数据         .forPath("/node2/node2","node2".getBytes());   异步方式创建（删除、更新、查询省略）： ct.create()         //父节点不存在则创建         .creatingParentsIfNeeded()         //节点类型         .withMode(CreateMode.PERSISTENT)         //节点权限         .withACL(ZooDefs.Ids.OPEN_ACL_UNSAFE)         //异步回调         .inBackground(new BackgroundCallback() {             public void processResult(CuratorFramework client, CuratorEvent event) throws Exception {                 System.out.println(event.getPath()+":"+event.getType());             }         })         //节点路径和数据         .forPath("node3","node3".getBytes());

　　

3.更新节点

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1	ct.setData().withVersion(-1).forPath("/node3","node33".getBytes());

　　

4.删除节点

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ct.delete().withVersion(-1).forPath("/node3"); 　删除包含子节点的节点   //递归删除 ct.delete()          .deletingChildrenIfNeeded()          .withVersion(-1).forPath("/node2");

　　

5.查询节点

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//查询 byte[] bytes = ct.getData().forPath("/node1"); System.out.println(new String(bytes));   读取属性： Stat stat = new Stat(); byte[] bytes = ct.getData()      .storingStatIn(stat).forPath("/node1"); System.out.println(new String(bytes)); System.out.println(stat);

　　

6.查询子节点数据

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//  /ct/node1/node2 List<String> list = ct.getChildren().forPath("/node1"); for (String s : list) {        System.out.println(s); }

　　

7.判断节点是否存在

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1 2	//如果节点不存在，则返回值为null Stat stat = ct.checkExists().forPath("/node11");