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2、zookeeper系列 -- 简单学习 zk 提供的 java API

前置声明

maven

<dependencies>
    <dependency>
        <groupId>org.apache.zookeeper</groupId>
        <artifactId>zookeeper</artifactId>
        <version>3.5.5</version>
    </dependency>
</dependencies>

创建会话

public class MyZookeeper implements Watcher {

    private static CountDownLatch latch = new CountDownLatch(1);

    public static void main(String[] args) {
        try {
            ZooKeeper zooKeeper = new ZooKeeper("192.168.1.102:2181", 5000, new MyZookeeper());
            System.out.println(zooKeeper.getState());
            try {
                latch.await();
            } catch (InterruptedException e) {
            }
            System.out.println("zookeeper session established");
        } catch (IOException e) {
        }
    }


    @Override
    public void process(WatchedEvent event) {
        System.out.println("Receive watched event：" + event);
        if (KeeperState.SyncConnected == event.getState()) {
            latch.countDown();
        }
    }
}

创建节点

public String create(final String path, byte data[], List<ACL> acl, CreateMode createMode)

zooKeeper.create("/zk-1", "hello".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);

删除节点

public void delete(final String path, int version) throws InterruptedException, KeeperException

zooKeeper.delete("/zk-book", -1);

描述：

version： 这里的version，表示的是dataVersion。-1，表示匹配任何一个版本。

public void delete(final String path, int version, VoidCallback cb, Object ctx)

zooKeeper.delete("/zk-book", -1, (int rc, String path, Object context) -> {
            System.out.printf("rc = %d/npath = %s/ncontext = %s/n", rc, path, path, context.toString());
        }, "I am context data");
Thread.sleep(3000);

描述：

异步删除
Object ctx： 上下文数据，可传递到回调函数
VoidCallback cb： 回调函数

获取节点

public List<String> getChildren(final String path, Watcher watcher) throws KeeperException, InterruptedException

List<String> children = zooKeeper.getChildren("/zk-book", new MyZookeeper());
children.forEach(System.out::println);

描述：

获取该节点下的直接子节点，无法递归获取（zk client 的 ls -R /zk-book 可递归获取）

public void getChildren(final String path, Watcher watcher, Children2Callback cb, Object ctx)

zooKeeper.getChildren("/zk-book", new MyZookeeper(), (int rc, String path, Object ctx, List<String> children, Stat stat) -> System.out.printf("rc = %d/tpath = %s/tctx = %s/tchidren = %s/tstat = %s/n", rc, path, ctx, String.join(",", children),stat.toString()), "I am callback data");
zooKeeper.create("/zk-book/zb3", "hello".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
Thread.sleep(3000);

描述：

异步获取数据
当注册监听的时候，/zk-book 下的节点若改变，则会触发 NodeChildrenChanged 事件。

读取数据

public byte[] getData(final String path, Watcher watcher, Stat stat)throws KeeperException, InterruptedException

byte[] data = zooKeeper.getData("/zk-book", new MyZookeeper(), null);
System.out.println(new String(data, 0, data.length));

public void getData(final String path, Watcher watcher, DataCallback cb, Object ctx)

zooKeeper.getData("/zk-book", new MyZookeeper(), (int rc, String path, Object ctx, byte data[], Stat stat) -> {}, null);
Thread.sleep(3000);

描述

异步获取数据

更新数据

public Stat setData(final String path, byte data[], int version) throws KeeperException, InterruptedException

Stat stat1 = zooKeeper.setData("/zk-book", "hello".getBytes(), -1);

public void setData(final String path, byte data[], int version, StatCallback cb, Object ctx)

zooKeeper.setData("/zk-book", "hello".getBytes(), -1, (int rc, String path, Object ctx, Stat stat) ->{},  null);
Thread.sleep(3000);

描述

异步更新数据

检查是否存在

public Stat exists(final String path, Watcher watcher) throws KeeperException, InterruptedException

Stat exists = zooKeeper.exists("/zk-book", new MyZookeeper());

描述

Watcher watcher监听 3 类事件。
- 节点被创建
- 节点被删除
- 节点被更新

public void exists(final String path, Watcher watcher, StatCallback cb, Object ctx)

zooKeeper.exists("/zk-book", new MyZookeeper(), (int rc, String path, Object ctx, Stat stat) -> {}, null);

描述

异步判断是否存在

原文 https://segmentfault.com/a/1190000020805477

正文到此结束

所属分类： Java 编程技术

本文标签： tab IDE IO apache 数据删除 zookeeper http cat client 递归 final Watcher https dependencies CountDownLatch maven list session node NSA id
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2、zookeeper系列 -- 简单学习 zk 提供的 java API

前置声明

maven

创建会话

创建节点

public String create(final String path, byte data[], List<ACL> acl, CreateMode createMode)

删除节点

public void delete(final String path, int version) throws InterruptedException, KeeperException

描述：

public void delete(final String path, int version, VoidCallback cb, Object ctx)

描述：

获取节点

public List<String> getChildren(final String path, Watcher watcher) throws KeeperException, InterruptedException

描述：

public void getChildren(final String path, Watcher watcher, Children2Callback cb, Object ctx)

描述：

读取数据

public byte[] getData(final String path, Watcher watcher, Stat stat)throws KeeperException, InterruptedException

public void getData(final String path, Watcher watcher, DataCallback cb, Object ctx)

描述

更新数据

public Stat setData(final String path, byte data[], int version) throws KeeperException, InterruptedException

public void setData(final String path, byte data[], int version, StatCallback cb, Object ctx)

描述

检查是否存在

public Stat exists(final String path, Watcher watcher) throws KeeperException, InterruptedException

描述

public void exists(final String path, Watcher watcher, StatCallback cb, Object ctx)

描述

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