Zookeeper实战案例（1）

前置知识：

Zookeeper学习笔记（1）—— 基础知识-CSDN博客

Zookeeper学习笔记（2）—— Zookeeper API简单操作-CSDN博客

Zookeeper 服务器动态上下线监听案例

需求分析

某分布式系统中，主节点可以有多台，可以动态上下线，任意一台客户端都能实时感知到主节点服务器的上下线

具体实现

首先创建节点servers：create /servers "servers"

服务器向zookeeper注册的代码

package com.why.zkCase;import org.apache.zookeeper.*;
import org.junit.Before;import java.io.IOException;//服务端向zookeeper注册
public class DistributeServer {private static String connetString = "hadoop102:2181,hadoop103:2181,hadoop104:2181"; //客户端连接ipprivate static int sessionTimeout = 2000; //超时时间private ZooKeeper zkClient = null; //客户端对象private String parentNode = "/servers"; //父节点路径@Beforepublic void getConnect() throws IOException {zkClient = new ZooKeeper(connetString, sessionTimeout, new Watcher() {@Overridepublic void process(WatchedEvent watchedEvent) {//收到事件通知后的回调函数System.out.println("事件类型:" + watchedEvent.getType());System.out.println("事件路径:" + watchedEvent.getPath());}});}//注册服务器public void registServer(String hostname) throws InterruptedException, KeeperException {String create = zkClient.create(parentNode + "/server", hostname.getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);System.out.println(hostname + "is online" + create);}//业务逻辑public void business(String hostname) throws Exception {System.out.println(hostname + " is working ...");Thread.sleep(Long.MAX_VALUE);}public static void main(String[] args) throws Exception {// 1 获取 zk 连接DistributeServer server = new DistributeServer();server.getConnect();// 2 利用 zk 连接注册服务器信息server.registServer(args[0]);// 3 启动业务功能server.business(args[0]);}
}

客户端代码

package com.why.zkCase;import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.junit.Before;import java.io.IOException;
import java.util.ArrayList;
import java.util.List;//客户端
public class DistributeClient {private static String connetString = "hadoop102:2181,hadoop103:2181,hadoop104:2181"; //客户端连接ipprivate static int sessionTimeout = 2000; //超时时间private ZooKeeper zkClient = null; //客户端对象private String parentNode = "/servers"; //父节点路径//创建到zk的客户端连接@Beforepublic void getConnect() throws IOException {zkClient = new ZooKeeper(connetString, sessionTimeout, new Watcher() {@Overridepublic void process(WatchedEvent watchedEvent) {//收到事件通知后的回调函数System.out.println("事件类型:" + watchedEvent.getType());System.out.println("事件路径:" + watchedEvent.getPath());// 再次启动监听try {getServerList();} catch (Exception e) {e.printStackTrace();}}});}//获取服务器列表信息public void getServerList() throws InterruptedException, KeeperException {//获取服务器子节点信息，并对父节点进行监听List<String> children = zkClient.getChildren(parentNode, true);//存储服务器信息列表ArrayList<String> servers = new ArrayList<>();//遍历所有节点，获取主机名称信息for (String child : children){byte[] data = zkClient.getData(parentNode + "/" + child, false, null);servers.add(new String(data));}//打印服务器列表信息System.out.println(servers);}// 业务功能public void business() throws Exception{System.out.println("client is working ...");Thread.sleep(Long.MAX_VALUE);}public static void main(String[] args) throws Exception {// 1 获取 zk 连接DistributeClient client = new DistributeClient();client.getConnect();// 2 获取 servers 的子节点信息，从中获取服务器信息列表client.getServerList();// 3 业务进程启动client.business();}
}