Zookeeper--05---客户端API操作

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客户端API操作

依赖前提：1.创建 ZooKeeper客户端2.创建子节点

create 方法acl----- 权限CreateMode -----节点类型 (持久 还是 临时节点) 3.获取子节点 并监听节点变化

注意设置的监听,只监听一次,如果重复监听,得设置监听得process再次注册 4.判断 Znode是否存在

            junit
            junit
            RELEASE
        

        
            org.apache.logging.log4j
            log4j-core
            2.8.2
        

        
            org.apache.zookeeper
            zookeeper
            3.5.7
        

保证 hadoop102、hadoop103、hadoop104服务器上 服务器上 Zookeeper集群服务端启动。
1.创建 ZooKeeper客户端

public class zkClient {

    // 注意：逗号左右不能有空格
    private String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
    private int sessionTimeout = 2000;
    private ZooKeeper zkClient;

    @Before
    public void init() throws IOException {

        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {

//                System.out.println("-------------------------------");
//                List children = null;
//                try {
//                    children = zkClient.getChildren("/", true);
//
//                    for (String child : children) {
//                        System.out.println(child);
//                    }
//
//                    System.out.println("-------------------------------");
//                } catch (KeeperException e) {
//                    e.printStackTrace();
//                } catch (InterruptedException e) {
//                    e.printStackTrace();
//                }
            }
        });
    }
}

    @Test
    public void create() throws KeeperException, InterruptedException {
        String nodeCreated = zkClient.create("/atguigu", "ss.avi".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    }

String path, 节点路径byte data[], 存储内容List acl, 权限CreateMode createMode 节点类型 (持久 还是 临时节点)
acl----- 权限

持久节点持久序号节点临时节点临时序号节点Container节点TTL节点

    @Before
    public void init() throws IOException {

        zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {

        });
    }


    @Test
    public void getChildren() throws KeeperException, InterruptedException {
        List children = zkClient.getChildren("/", true);

        for (String child : children) {
            System.out.println(child);
        }

        // 延时
        Thread.sleep(Long.MAX_VALUE);
    }

注意设置的监听,只监听一次,如果重复监听,得设置监听得process再次注册

    @Test
    public void exist() throws KeeperException, InterruptedException {

        Stat stat = zkClient.exists("/atguigu", false);

        System.out.println(stat==null? "not exist " : "exist");
    }