ZooKeeper实战（四）-ZooKeeper API使用

本篇文章主要介绍如何使用ZooKeeper官方API来操作ZooKeeper。

maven依赖

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

ZooKeeper API

构造ZooKeeper实例

我们主要使用的是ZooKeeper 类来访问ZooKeeper 并执行一系列操作。

String hostPort = "localhost:2181,localhost:2182,localhost:2183";
int sessionTimeout = 3000;
String path = "/test/app1";

ZooKeeper zk = new ZooKeeper(hostPort, sessionTimeout, new Watcher() {

            @Override
            public void process(WatchedEvent event) {
                String path = event.getPath();
                System.out.println("watch:"+event.getType()+",path:"+path);

            }
        });

新建znode节点

public void create(){

        String data = "hello world!";

        System.out.println("create data:"+data);

        try {
            String result = zk.create(path, data.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            System.out.println(result);
        } catch (KeeperException | InterruptedException e) {
            e.printStackTrace();
        }
    }

get znode节点数据

    public void get(){

        String result = null;  
        try {  
            byte[] bytes = zk.getData(path, null, null);  
            result = new String(bytes);  
       } catch (Exception e) {  
            e.printStackTrace();
       }
       System.out.println("read data:"+result);
    }

set znode节点数据

public void set(){

        String data = "hello ricky!";

        System.out.println("set data:"+data);
        try {
            zk.setData(path, data.getBytes(), -1);
        } catch (KeeperException | InterruptedException e) {
            e.printStackTrace();
        }
    }

delete znode

public void delete(){

        try {
            zk.delete(path, -1);
        } catch (InterruptedException | KeeperException e) {
            e.printStackTrace();
        }
    }

close ZooKeeper

public void close(){

        try {
            zk.close();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

完整代码如下：

package com.ricky.codelab.zookeeper;

import java.io.IOException;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;

public class ZKCrudDemo {

    private String hostPort = "localhost:2181,localhost:2182,localhost:2183";
    private int sessionTimeout = 3000;
    private String path = "/test/app1";

    private ZooKeeper zk;

    public static void main(String[] args) {

        try {
            new ZKCrudDemo().test();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public void test() throws IOException{

        zk = new ZooKeeper(hostPort, sessionTimeout, new Watcher() {

            @Override
            public void process(WatchedEvent event) {
                String path = event.getPath();
                System.out.println("watch:"+event.getType()+",path:"+path);

            }
        });

// create();
// get();
// 
// set();
        get();

        delete();
        get();

        close();
    }

    public void create(){

        String data = "hello world!";

        System.out.println("create data:"+data);

        try {
            String result = zk.create(path, data.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
            System.out.println(result);
        } catch (KeeperException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void get(){

        String result = null;  
        try {  
            byte[] bytes = zk.getData(path, null, null);  
            result = new String(bytes);  
       } catch (Exception e) {  
            e.printStackTrace();
       }
       System.out.println("get data:"+result);
    }

    public void set(){

        String data = "hello ricky!";

        System.out.println("set data:"+data);
        try {
            zk.setData(path, data.getBytes(), -1);
        } catch (KeeperException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void delete(){

        try {
            zk.delete(path, -1);
        } catch (InterruptedException | KeeperException e) {
            e.printStackTrace();
        }
    }

    public void close(){

        try {
            zk.close();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

参考资料：
https://zookeeper.apache.org/doc/trunk/javaExample.html
http://zookeeper.apache.org/doc/r3.4.8/api/org/apache/zookeeper/ZooKeeper.html