3 Zookeeper java官方客户端使用

一客户端种类

zookeeper有三种Java客户端:

Zookeeper,Zookeeper官方提供的原生Java客户端
Zkclient,在原生Zookeeper基础上进行扩展的开源第三方Java客户端
Curator,Netflix公司在原生zookeeper基础上开源的Java客户端
今天我们简单说一下第1种，下一篇详细说一下第3种。

二 Zookeeper官方客户端的使用

引入maven，具体版本最好和服务端zookeeper版本一致，因为我们安装的是apache-zookeeper-3.5.10

<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.5.10</version>
</dependency>

连接zookeeper

connStr：ZooKeeper服务器列表，由英文逗号分开的host:port字符串组成，每一个都代表一台ZooKeeper机器，如，host1:port1,host2:port2,host3:port3。另外，也可以在connectString中设置客户端连接上ZooKeeper后的根目录，方法是在host:port字符串之后添加上这个根目录，例如,host1:port1,host2:port2,host3:port3/zk-base,这样就指定了该客户端连接上ZooKeeper服务器之后,所有对ZooKeeper的操作，都会基于这个根目录。例如，客户端对/sub-node 的操作，最终创建 /zk-node/sub-node, 这个目录也叫Chroot，即客户端隔离命名空间。
sessionTimeout：会话的超时时间，是一个以“毫秒”为单位的整型值。在ZooKeeper中有
会话的概念，在一个会话周期内，ZooKeeper客户端和服务器之间会通过心跳检
测机制来维持会话的有效性，一旦在sessionTimeout时间内没有进行有效
的心跳检测，会话就会失效。

private static final String ZK_ADDRESS = "192.168.59.130:2181";
private static final int SESSION_TIMEOUT = 5000;

public static ZooKeeper getZKclient(String connStr, int sessionTimeout){
    try {
        CountDownLatch countDownLatch = new CountDownLatch(1);
        ZooKeeper zkClient = new ZooKeeper(connStr, sessionTimeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                if(Event.KeeperState.SyncConnected == watchedEvent.getState()){
                    if(Event.EventType.None == watchedEvent.getType()){
                        //如果收到了服务端的响应事件，连接成功
                        System.out.println("zookeeper服务器连接成功！");
                        countDownLatch.countDown();
                    }

                }
            }
        });
        countDownLatch.await();
        System.out.println("状态："+zkClient.getState());
        return zkClient;
    } catch (IOException e) {
        e.printStackTrace();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    return null;
}

创建节点

public static void createNode(ZooKeeper zkClient){
    try {
        //需要手动创建父节点
        zkClient.create(ZNODE_PATH,
                "data1".getBytes(),
                //zookeeper提供了几个默认的权限列表，在ZooDefs.Ids中
                ZooDefs.Ids.OPEN_ACL_UNSAFE,
                CreateMode.PERSISTENT);
        System.out.println("节点创建成功！");
    } catch (KeeperException e) {
        e.printStackTrace();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

获取节点数据，可同步获取数据，异步获取数据，添加数据监听。
注意：在做异步监听测试时，需要代码最后添加TimeUnit.SECONDS.sleep(100);线程睡眠防止程序结束，回调不触发。

public static void getData(ZooKeeper zkClient) {
    Stat stat = new Stat();
    try {
        //1. 同步获取节点数据
        byte[] data = zkClient.getData(ZNODE_PATH, false, stat);
        System.out.println("nodeVal: "+new String(data)+"，state:"+stat);

        //2. 异步获取节点数据
        String ctxParam = "ctxVal";
        zkClient.getData(ZNODE_PATH, false, new AsyncCallback.DataCallback() {
            @Override
            public void processResult(int rc, String path, Object ctx, byte[] data, Stat stat) {
                System.out.println("rc:"+rc+",path:"+path+",ctx:"+ctx+",data:"+new String(data)+",stat:"+stat);
            }
        },ctxParam);

        //3. 同步获取数据添加监听
        zkClient.getData(ZNODE_PATH,new Watcher() {
                    @Override
                    public void process(WatchedEvent watchedEvent) {
                        System.out.println("触发同步监听：");
                        System.out.println("receive node："+watchedEvent.getPath());
                        System.out.println("watchedEvent："+watchedEvent.toString());
                    }
                }, stat);
        //修改节点数据，触发监听
        zkClient.setData(ZNODE_PATH,"data2".getBytes(),stat.getVersion());

        //4. 异步获取数据添加监听
        zkClient.getData(ZNODE_PATH, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                System.out.println("触发异步监听：");
                System.out.println("receive node："+watchedEvent.getPath());
                System.out.println("watchedEvent："+watchedEvent.toString());
            }
        }, new AsyncCallback.DataCallback() {
            @Override
            public void processResult(int rc, String path, Object ctx, byte[] data, Stat stat) {
                System.out.println("rc:"+rc+",path:"+path+",ctx:"+ctx+",data:"+new String(data)+",stat:"+stat);
            }
        },ctxParam);

        Stat stat2 = new Stat();
        zkClient.getData(ZNODE_PATH,false, stat2);
        zkClient.setData(ZNODE_PATH,"data2".getBytes(),stat2.getVersion());

    } catch (KeeperException e) {
        e.printStackTrace();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

删除节点

public static void deleteData(ZooKeeper zkClient) {
    try {
        String nodePath = ZNODE_PATH+"/node1";
        //创建节点，用于测试删除
        zkClient.create(nodePath,
                "data1".getBytes(),
                ZooDefs.Ids.OPEN_ACL_UNSAFE,
                CreateMode.PERSISTENT);

        List<String> children = zkClient.getChildren(ZNODE_PATH, false);
        System.out.println("删除前children："+children.toString());

        Stat stat = new Stat();
        byte[] data = zkClient.getData(nodePath, false, stat);
        System.out.println("nodeVale："+new String(data));
        zkClient.delete(nodePath,stat.getVersion());
        children = zkClient.getChildren(ZNODE_PATH, false);
        System.out.println("删除后children："+children.toString());
    } catch (KeeperException e) {
        e.printStackTrace();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

public static void getChildren(ZooKeeper zkClient){
    try{

        List<String> children = zkClient.getChildren(ZNODE_PATH, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                System.out.println("触发子节点列表变化通知：");
                System.out.println("receive nodeChange：" + watchedEvent.getPath());
                System.out.println("watchedEvent:" + watchedEvent);
            }
        });

        String nodePath = ZNODE_PATH+"/node1";
        //创建节点
        zkClient.create(nodePath,
                "data1".getBytes(),
                ZooDefs.Ids.OPEN_ACL_UNSAFE,
                CreateMode.PERSISTENT);

    }catch (Exception e){
        e.printStackTrace();
    }
}

3 Zookeeper java官方客户端使用

一 客户端种类

二 Zookeeper官方客户端的使用

一客户端种类