分布式系统从服务器获取时间

import java.rmi.*; import java.rmi.server.UnicastRemoteObject; import java.rmi.RemoteException; import java.awt.BorderLayout; import java.awt.Button; import java.awt.Color; import java.awt.Font; import java.awt.Frame; import java.awt.GridLayout; import java.awt.Label; import java.awt.Panel; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.net.InetAddress; import java.net.MalformedURLException; import java.net.UnknownHostException; import java.text.SimpleDateFormat; import java.util.*; //import TimeProvider; public class TimeServer extends UnicastRemoteObject implements java.io.Serializable,TimeServerInterface { private static final long serialVersionUID = 1L; LinkedList<TimeClientInterface> subscriberList = new LinkedList<TimeClientInterface>();//TimeSubscriber表 public GraphicServerInterface graphic_interface = null; private Timer timer = null; private int count = 0;// 计数器，以秒为单位 private int clientCnt = 0;// 连接的客户端数量 private boolean server_bound = false; // 服务是否已注册绑定 // 更新客户端连接数 public void updateClinetCnt(int count) { clientCnt += count; graphic_interface.LShowClientCnt.setText("The total count of the clients connected is " + clientCnt); } // 客户端连接服务器 public void Attach(TimeClientInterface time_subscriber)throws RemoteException { subscriberList.add(time_subscriber); updateClinetCnt(1); System.out.println("A new time subscriber has connected."); } //客户端断开连接 public void Detach(TimeClientInterface time_subscriber)throws RemoteException { if(subscriberList.remove(time_subscriber)) { updateClinetCnt(-1); System.out.println("A time subscriber has disconnected."); } else { System.out.println("Disconnection failed!"); } } //通知客户端更新时间 public void Notify()throws RemoteException { if(subscriberList.isEmpty()) //无客户端连接，返回 { return; } ListIterator<TimeClientInterface> subscriberLI = subscriberList.listIterator(); TimeClientInterface time_subscriber = null; while(subscriberLI.hasNext()) { time_subscriber = (TimeClientInterface)subscriberLI.next(); if(count % time_subscriber.GetInterval() == 0) { time_subscriber.Update(new Date()); } } ++count; if(count % 3600 == 0) //计数器每小时清零一次 { count = 0; } } // 终止服务 public void Terminate() throws RemoteException { if(!server_bound) { return;// 服务已终止，返回 } if(!subscriberList.isEmpty()) //无客户端连接，返回 { timer.cancel();// 停止服务器和客户端的时间更新 ListIterator<TimeClientInterface> subscriberLI = subscriberList.listIterator(); TimeClientInterface time_subscriber = null; while(subscriberLI.hasNext()) { time_subscriber = (TimeClientInterface)subscriberLI.next(); time_subscriber.Terminate();// 断开每个客户端 } subscriberList.clear();// 清空客户端列表 } try { Naming.unbind("//localhost:1099/TimeServer");// 终止服务绑定 server_bound = false; } catch (MalformedURLException e) { e.printStackTrace(); } catch (NotBoundException e) { e.printStackTrace(); } updateClinetCnt(-clientCnt); } //定时任务 class TaskTicker extends TimerTask { public void run() { try { SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); graphic_interface.LShowCurTime.setText(formatter.format(new Date()));// 更新服务器显示时间 Notify(); } catch(RemoteException re) { System.out.println("Remote exception" + re.toString()); } } } public TimeServer() throws RemoteException,MalformedURLException { graphic_interface = new GraphicServerInterface(); } public static void main(String args[])throws RemoteException,MalformedURLException { final TimeServer time_Server = new TimeServer(); //关闭服务器前检查是否还有客户端连接，若有，关闭之 Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { try { time_Server.Terminate(); } catch (RemoteException e) { System.out.println("Remote eexception" + e.toString()); } } }); } class GraphicServerInterface extends Frame { private static final long serialVersionUID = 1L; Panel PInformation; Panel PShowClientCnt; Panel PButton; Label LIP; Label LCurTime; Label LShowClientCnt; Label LShowIP; Label LShowCurTime; //Label LClientCnt; Button Start, Stop; public GraphicServerInterface() { setTitle("Server"); addWindowListener(new WindowAdapter(){ public void windowClosing(WindowEvent e){ try { Terminate(); } catch (RemoteException e1) { System.out.println( "Remote exception" + e1.toString()); } dispose(); System.exit(1); } }); setLocation(250,250); setSize(600,480); setResizable(false); PInformation = new Panel(); PInformation.setLayout(new GridLayout(1, 5)); PInformation.setBackground(new Color(255,253,225)); PShowClientCnt = new Panel(); PShowClientCnt.setLayout(new GridLayout(2, 1)); PShowClientCnt.setBackground(new Color(255,253,225)); PButton = new Panel(); PButton.setLayout(new GridLayout(1, 2)); PButton.setBackground(new Color(255,253,225)); //服务启动连接按钮 Start = new Button("Start"); Start.setFont(new Font("Times New Roman",Font.PLAIN,12)); Start.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent ae) { try { Naming.rebind("rmi://localhost:1099/TimeServer", TimeServer.this); System.out.println("Server is ready!"); timer = new Timer(); timer.scheduleAtFixedRate(new TaskTicker(),1000,1000);//一秒一次 server_bound = true; Start.setEnabled(false); Stop.setEnabled(true); } catch(Exception e) { System.out.println( "dd"+e.toString()); } } }); //断开服务器 Stop = new Button("ShutDown"); Stop.setFont(new Font("Times New Roman",Font.PLAIN,12)); Stop.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { try{ Terminate(); Start.setEnabled(true); Stop.setEnabled(false); System.out.println( "Server has been shut down!"); } catch(RemoteException re) { System.out.println( "Remote exception" + re.toString()); } } }); Stop.setEnabled(false); LIP=new Label("Local IP:"); LIP.setFont(new Font("Times New Roman",Font.BOLD,15)); LIP.setAlignment(1); LCurTime = new Label("Current Time: "); LCurTime.setFont(new Font("Times New Roman", Font.BOLD, 15)); LCurTime.setAlignment(1); String localIP = "127.0.0.1"; try { localIP = InetAddress.getLocalHost().getHostAddress(); } catch (UnknownHostException e1) { System.out.println("The IP of localhost is unknown!"); } LShowIP = new Label(localIP); LShowIP.setAlignment(1); SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); LShowCurTime = new Label(formatter.format(new Date())); LShowCurTime.setAlignment(1);