Zookeeper的API案例

最新推荐文章于 2025-08-11 14:42:51 发布

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本文详细介绍了如何在Maven项目中配置ZooKeeper依赖，并通过示例展示了ZooKeeper的基本API操作，包括创建节点、监听节点变化、读取和修改节点数据等。同时，还提供了服务器节点动态上下线的具体实现，包括服务器端和客户端的代码。

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配置

maven项目中的porn文件

<dependencies>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-core</artifactId>
			<version>2.8.2</version>
		</dependency>
		<!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper -->
		<dependency>
			<groupId>org.apache.zookeeper</groupId>
			<artifactId>zookeeper</artifactId>
			<version>3.4.10</version>
		</dependency>
</dependencies>

资源文件夹下创建log4j.properties，

log4j.rootLogger=INFO, stdout  
log4j.appender.stdout=org.apache.log4j.ConsoleAppender  
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout  
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n  
log4j.appender.logfile=org.apache.log4j.FileAppender  
log4j.appender.logfile.File=target/spring.log  
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout  
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

基础API操作

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;

public class TestZookeeper {

    ZooKeeper zkCli;

    /**
     * 测试客户端对象
     * @throws IOException
     */

    @Before
    public void testZkClient() throws IOException {
        String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
        int sessionTimeout = 10000;
        zkCli = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            public void process(WatchedEvent event) {

            }
        });

        System.out.println("zooKeeper = " + zkCli);
    }

    /**
     * 测试创建节点
     * @throws KeeperException
     * @throws InterruptedException
     */

    @Test
    public void testCreate() throws KeeperException, InterruptedException {
        String PATH = zkCli.create("/zzuli/fei", "cai".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        System.out.println("PATH = " + PATH);
    }

    /**
     * 监听节点的变化
     * @throws Exception
     */
    @Test
    public void testGetChildren() throws Exception{
        List<String> children = zkCli.getChildren("/zzuli", new Watcher() {
            public void process(WatchedEvent event) {
                System.out.println("节点已经发生了变化！");
            }
        });
        System.out.println("children = " + children);
        Thread.sleep(Long.MAX_VALUE);
    }

    /**
     * 其他API
     */
    @Test
    public void testOtherApi() throws Exception{
        // 判断节点是否存在
        Stat exists = zkCli.exists("/zzuli/fei", false);
        System.out.println("exists = " + exists);

        // 获取节点内容 (stat 为null，就是不传结构体)
        byte[] data = zkCli.getData("/zzuli/tang", false, null);
        System.out.println("data = " + data.toString());

        // 设置节点内容
        Stat stat = zkCli.setData("/zzuli/tang", "tang ge is ugly".getBytes(), -1);
        System.out.println("stat = " + stat);

        // 删除节点
        zkCli.delete("/zzuli/tang",-1);

    }



}

实现服务器节点动态上下线

server端：

package com.zzuli.exer;

import org.apache.zookeeper.*;

public class Server {

    private String connectString = "hadoop102:2181,hadoop103:2181,hadoop104:2181";
    private int sessionTimeout = 10000;
    private ZooKeeper zk = null;
    private String parentNode = "/servers";

    public static void main(String[] args) throws Exception {
        Server server = new Server();
        // 1 连接zookeeper集群
        server.getConnect();

        // 2 向集群注册服务器
        server.registServer(args[0]);

        // 3 启动业务功能
        server.run();

        Thread.sleep(Long.MAX_VALUE);
    }

    private void run() {
        System.out.println("业务启动！");
    }

    private void registServer(String arg) throws Exception{

        String path = zk.create(parentNode + "/server", arg.getBytes(),
                ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);
        System.out.println("创建成功：path = " + path);
    }

    private void getConnect() throws Exception{

        zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            public void process(WatchedEvent event) {

            }
        });

    }
}

Client端：

package com.zzuli.exer;

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

import java.util.List;

public class Client {

    ZooKeeper zk = null;
    private String connectString="hadoop102:2181,hadoop103:2181,hadoop104:2181";
    private int sessionTimeOut = 10000;

    public static void main(String[] args) throws Exception{
        // 1 创建zookeeper客户端对象
        Client client = new Client();
        client.init();

        // 2 获取当前在线的服务器
        client.connect();

        // 3 保证与zk的连接
        Thread.sleep(Long.MAX_VALUE);
    }

    private void connect() throws Exception{
        List<String> children = zk.getChildren("/servers", new Watcher() {
            public void process(WatchedEvent event) {
                try {
                    connect();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
        System.out.println("当前的连接数："+children);
    }

    private void init() throws Exception {
        zk = new ZooKeeper(connectString, sessionTimeOut, new Watcher() {
            public void process(WatchedEvent event) {

            }
        });
        System.out.println("客户端创建成功！");
    }
}