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利用ZooKeeper开发分布式应用系统案例--服务端与客户端实现
服务端代码：
package cn.edu360.zk.distributesystem;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;
import org.apache.zookeeper.data.Stat;public class TimeQueryServer {ZooKeeper zk = null;//启动zk客户端连接public void connectZK() throws Exception {zk = new ZooKeeper("hadoop1:2181,hadoop2:2181,hadoop3:2181", 2000, null);}//注册服务器信息public void registerServerInfo(String hostname,String port) throws Exception, InterruptedException {/** 先判断注册节点是否存在，如果不存在，则创建*/Stat stat = zk.exists("/servers", false);if(stat == null) {zk.create("/servers", null, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}//注册服务器数据到zk的约定注册节点下String create = zk.create("/servers/server", (hostname + ":" + port).getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);System.out.println(hostname + "服务器向zk注册信息成功，注册的节点为：" + create);}//启动业务线程开始处理业务public static void main(String[] args) throws Exception, Exception {TimeQueryServer timeQueryServer = new TimeQueryServer();//启动zk客户端连接timeQueryServer.connectZK();//注册服务器信息timeQueryServer.registerServerInfo(args[0], args[1]);//启动业务线程开始处理业务new TimeQueryService(Integer.parseInt(args[1])).start();}}
服务端线程代码：
package cn.edu360.zk.distributesystem;import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Date;public class TimeQueryService extends Thread{int port = 0;public TimeQueryService(int port) {this.port = port;}@Overridepublic void run() {try {ServerSocket ss = new ServerSocket(port);System.out.println("业务线程已绑定端口"+ port + "准备接受消费端请求了...");while(true) {Socket sc = ss.accept();InputStream inputStream = sc.getInputStream();OutputStream outputStream = sc.getOutputStream();outputStream.write(new Date().toString().getBytes());}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}
客户端代码：
package cn.edu360.zk.distributesystem;import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooKeeper;public class Consumer {//定义一个list用于存放最新的在线服务器列表private volatile ArrayList<String> onlineServers = new ArrayList<String>();//构造zk连接对象ZooKeeper zk = null;public void connectZK() throws Exception {zk = new ZooKeeper("hadoop1:2181,hadoop2:2181,hadoop3:2181", 2000, new Watcher() {@Overridepublic void process(WatchedEvent event) {if(event.getState() == KeeperState.SyncConnected && event.getType() == EventType.NodeChildrenChanged) {try {//事件回调逻辑中，再次查询zk上的在线服务器节点即可，查询逻辑中又再次注册子节点事件监听。getOnlineServers();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}}});}//查询在线服务器列表public void getOnlineServers() throws Exception, InterruptedException {List<String> children = zk.getChildren("/servers", true);ArrayList<String> list = new ArrayList<String>();for (String child : children) {byte[] data = zk.getData("/servers/"+child, false, null);String serverInfo = new String(data);list.add(serverInfo);}onlineServers = list;System.out.println("查询了一次zk，当前在线的服务器有："+list);}public void sendRequest() throws Exception {Random random = new Random();while(true) {try {//挑选一台当前在线的服务器 int nextInt = random.nextInt(onlineServers.size());String server = onlineServers.get(nextInt);String hostname = server.split(":")[0];int port = Integer.parseInt(server.split(":")[1]);System.out.println("本次请求挑选的服务器为：" + server);Socket socket = new Socket(hostname, port);OutputStream outputStream = socket.getOutputStream();outputStream.write("haha".getBytes());outputStream.flush();InputStream inputStream = socket.getInputStream();byte[] buf = new byte[256];int read = inputStream.read(buf);System.out.println("服务器相应的时间为" + new String(buf,0,read));outputStream.close();inputStream.close();socket.close();Thread.sleep(2000);}catch(Exception e) {e.printStackTrace();}}}public static void main(String[] args) throws Exception {Consumer consumer = new Consumer();//构造zk连接对象consumer.connectZK();//查询在线服务器列表consumer.getOnlineServers();//处理业务（向一台服务器发送时间查询请求）consumer.sendRequest();}}
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