二十二、Zookeeper的API代码应用

       上篇文章主要讲述了Zookeeper的命令行操作，本文主要讲解Zookeeper的API代码应用，本文以代码为主，Zookeeper的部分相对来说都是比较简单的。关注专栏《破茧成蝶——大数据篇》查看相关系列文章~

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目录

一、添加pom.xml文件

二、查看Zookeeper中ZNode

三、创建节点

四、获取节点信息

五、修改节点内容

六、查看结构体

七、删除节点

八、循环注册节点

九、完整代码

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一、添加pom.xml文件

       在新建的Maven工程里面，添加如下依赖内容：

    
        junit
        junit
        RELEASE
    
    
        org.apache.logging.log4j
        log4j-core
        2.8.2
    
    
    
        org.apache.zookeeper
        zookeeper
        3.4.10
    

二、查看Zookeeper中ZNode

    /**
     * 查看ZNode中包含的节点
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void ls() throws KeeperException, InterruptedException {
        //默认回调函数
//        List children = zkCli.getChildren("/", true);
        //自定义回调函数
        List children = zkCli.getChildren("/", e -> {
            System.out.println("自定义回调函数");
        });

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

        Thread.sleep(Long.MAX_VALUE);
    }

三、创建节点

    /**
     * 创建节点
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void create() throws KeeperException, InterruptedException {
        String s = zkCli.create("/test", "test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
        System.out.println(s);

        Thread.sleep(Long.MAX_VALUE);
    }

四、获取节点信息

    /**
     * 获取节点信息
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void get() throws KeeperException, InterruptedException {
        byte[] data = zkCli.getData("/xzw", true, new Stat());

        String s = new String(data);

        System.out.println(s);
    }

五、修改节点内容

    /**
     * 修改节点内容
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void set() throws KeeperException, InterruptedException {
        Stat stat = zkCli.setData("/xzw", "test".getBytes(), 0);

        System.out.println(stat.getDataLength());
    }

六、查看结构体

    /**
     * 查看结构体
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void stat() throws KeeperException, InterruptedException {
        Stat exists = zkCli.exists("/xzw", false);
        if (exists == null) {
            System.out.println("节点不存在");
        } else {
            System.out.println(exists.getDataLength());
        }
    }

七、删除节点

    /**
     * 删除节点
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void delete() throws KeeperException, InterruptedException {
        Stat exists = zkCli.exists("/xzw", false);
        if (exists != null)
            zkCli.delete("/xzw", exists.getVersion());
    }

八、循环注册节点

    /**
     * 循环注册节点：当节点发生变化时，可以不停的通知
     * @throws KeeperException
     * @throws InterruptedException
     */
    public void register() throws KeeperException, InterruptedException {
        byte[] data = zkCli.getData("/xzw", new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                try {
                    register();
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, null);

        System.out.println(new String(data));
    }

    /**
     * 测试循环注册
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void testRegister() throws KeeperException, InterruptedException {
        register();
        Thread.sleep(Long.MAX_VALUE);
    }

九、完整代码

package com.xzw.zookeeper;

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.Stat;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.util.List;

/**
 * @author: xzw
 * @create_date: 2020/9/9 9:59
 * @desc: Zookeeper客户端
 * @modifier:
 * @modified_date:
 * @desc:
 */
public class ZkClient {

    //定义Zookeeper客户端实例
    private ZooKeeper zkCli;
    //定义连接串
    private static final String CONNECT_STRING = "master:2181,slave01:2181,slave02:2181";
    //定义session timeout
    private static final int SESSION_TIMEOUT = 2000;

    /**
     * 初始化Zookeeper，定义一个默认的回调函数
     * @throws IOException
     */
    @Before
    public void before() throws IOException {
        zkCli = new ZooKeeper(CONNECT_STRING, SESSION_TIMEOUT, e -> {
            System.out.println("默认回调函数");
        });
    }

    /**
     * 查看ZNode中包含的节点
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void ls() throws KeeperException, InterruptedException {
        //默认回调函数
//        List children = zkCli.getChildren("/", true);
        //自定义回调函数
        List children = zkCli.getChildren("/", e -> {
            System.out.println("自定义回调函数");
        });

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

        Thread.sleep(Long.MAX_VALUE);
    }

    /**
     * 创建节点
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void create() throws KeeperException, InterruptedException {
        String s = zkCli.create("/test", "test".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
        System.out.println(s);

        Thread.sleep(Long.MAX_VALUE);
    }

    /**
     * 获取节点信息
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void get() throws KeeperException, InterruptedException {
        byte[] data = zkCli.getData("/xzw", true, new Stat());

        String s = new String(data);

        System.out.println(s);
    }

    /**
     * 修改节点内容
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void set() throws KeeperException, InterruptedException {
        Stat stat = zkCli.setData("/xzw", "test".getBytes(), 0);

        System.out.println(stat.getDataLength());
    }

    /**
     * 查看结构体
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void stat() throws KeeperException, InterruptedException {
        Stat exists = zkCli.exists("/xzw", false);
        if (exists == null) {
            System.out.println("节点不存在");
        } else {
            System.out.println(exists.getDataLength());
        }
    }

    /**
     * 删除节点
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void delete() throws KeeperException, InterruptedException {
        Stat exists = zkCli.exists("/xzw", false);
        if (exists != null)
            zkCli.delete("/xzw", exists.getVersion());
    }

    /**
     * 循环注册节点：当节点发生变化时，可以不停的通知
     * @throws KeeperException
     * @throws InterruptedException
     */
    public void register() throws KeeperException, InterruptedException {
        byte[] data = zkCli.getData("/xzw", new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                try {
                    register();
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, null);

        System.out.println(new String(data));
    }

    /**
     * 测试循环注册
     * @throws KeeperException
     * @throws InterruptedException
     */
    @Test
    public void testRegister() throws KeeperException, InterruptedException {
        register();
        Thread.sleep(Long.MAX_VALUE);
    }
}

 

       至此，本文就结束了，你们在此过程中遇到了什么问题，欢迎留言，让我看看你们都遇到了哪些问题~