zk调用实例

pom文件引入zookeeper包

<dependency>
        <groupId>org.apache.zookeeper</groupId>
        <artifactId>zookeeper</artifactId>
        <version>3.4.8</version>
    </dependency>

连接zk并监听事件

/**
 * 连接zk并监听事件
 */
public class ZKDemo implements Watcher {
    private static final CountDownLatch cdl = new CountDownLatch(1);

    public static void main(String[] args) throws IOException {
        ZooKeeper zk = new ZooKeeper("10.143.143.185:6181", 5000, new ZKDemo());
        System.out.println(zk.getState());

        try {
            cdl.await();
        } catch (Exception e) {
            System.out.println("ZK Session established.");
        }
    }

    //监听到事件时进行处理
    @Override
    public void process(WatchedEvent event) {
        System.out.println("Receive watched event:" + event);
        if (KeeperState.SyncConnected == event.getState()) {
            cdl.countDown();
        }
    }
}

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如何创建znode并监听事件

/**
 * 创建znode并监听事件
 */
public class ZKOperateDemo implements Watcher {
    private static final CountDownLatch cdl = new CountDownLatch(1);

    public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
        ZooKeeper zk = new ZooKeeper("10.143.143.185:6181", 5000, new ZKOperateDemo());
        cdl.await();

        String path1 = zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        System.out.println("Success create path: " + path1);
        String path2 = zk.create("/zk-test", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL);
        System.out.println("Success create path: " + path2);
    }

    //监听到事件时进行处理
    @Override
    public void process(WatchedEvent event) {
        System.out.println("Receive watched event:" + event);
        if (KeeperState.SyncConnected == event.getState()) {
            cdl.countDown();
        }
    }
}

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改变znode数据并监听事件

/**
 * 改变znode数据并监听事件
 */
public class ZKDataDemo implements Watcher {
    private static final CountDownLatch cdl = new CountDownLatch(1);
    private static ZooKeeper zk = null;
    private static Stat stat = new Stat();

    public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
        zk = new ZooKeeper("10.143.143.185:6181", 5000, new ZKDataDemo());
        cdl.await();

        zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
        System.out.println(new String(zk.getData("/zk-test", true, stat)));

        zk.getData("/zk-test", true, stat);
        System.out.println(stat.getCzxid() + ", " + stat.getMzxid() + ", " + stat.getVersion());
        zk.setData("/zk-test", "456".getBytes(), -1);

        Thread.sleep(Integer.MAX_VALUE);
    }

    //监听到事件时进行处理
    @Override
    public void process(WatchedEvent event) {
        if (KeeperState.SyncConnected == event.getState()) {
            if (EventType.None == event.getType() && null == event.getPath()) {
                cdl.countDown();
            } else if (event.getType() == EventType.NodeDataChanged) {
                try {
                    System.out.println("path = " + event.getPath() +"      " + new String(zk.getData(event.getPath(), true, stat)));
                    System.out.println(stat.getCzxid() + ", " + stat.getMzxid() + ", " + stat.getVersion());
                } catch (Exception e) {
                }
            }
        }
    }
}

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改变子节点并监听事件

/**
 * 改变子节点并监听事件
 */
public class ZKChildrenDemo implements Watcher {
    private static final CountDownLatch cdl = new CountDownLatch(1);
    private static ZooKeeper zk = null;

    public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
        zk = new ZooKeeper("10.143.143.185:6181", 5000, new ZKChildrenDemo());
        cdl.await();

        zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);

        zk.create("/zk-test/c1", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

        List<String> list = zk.getChildren("/zk-test", true);
        for (String str : list)
            System.out.println(str);

        zk.create("/zk-test/c2", "789".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

        Thread.sleep(Integer.MAX_VALUE);
    }

    @Override
    public void process(WatchedEvent event) {
        if (KeeperState.SyncConnected == event.getState())
            if (EventType.None == event.getType() && null == event.getPath()) {
                cdl.countDown();
            } else if (event.getType() == EventType.NodeChildrenChanged) {
                try {
                    System.out.println("Child: " + zk.getChildren(event.getPath(), true));
                } catch (Exception e) {
                }
            }
    }
}

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异步调用并完成回调

//异步调用并完成回调
class ChildrenCallback implements AsyncCallback.Children2Callback {
    @Override
    public void processResult(int rc, String path, Object ctx, List<String> children, Stat stat) {
        System.out.println(
                "Child: " + rc + ", path: " + path + ", ctx: " + ctx + ", children: " + children + ", stat: " + stat);
    }
}

public class ZKChildrenAsyncDemo implements Watcher {
    private static final CountDownLatch cdl = new CountDownLatch(1);
    private static ZooKeeper zk = null;

    public static void main(String[] args) throws IOException, InterruptedException, KeeperException {
        zk = new ZooKeeper("10.143.143.185:6181", 5000, new ZKChildrenAsyncDemo());
        cdl.await();

        zk.create("/zk-test", "123".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);

        zk.create("/zk-test/c1", "456".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

        zk.getChildren("/zk-test", true, new ChildrenCallback(), "ok");

        Thread.sleep(Integer.MAX_VALUE);
    }

    @Override
    public void process(WatchedEvent event) {
        if (KeeperState.SyncConnected == event.getState())
            if (EventType.None == event.getType() && null == event.getPath()) {
                cdl.countDown();
            } else if (event.getType() == EventType.NodeChildrenChanged) {
                try {
                    System.out.println("Child: " + zk.getChildren(event.getPath(), true));
                } catch (Exception e) {
                }
            }
    }
}

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