高分，不够再加！！如何用java applet实现在客户端浏览器中显示即时的web server的系统时间

作个server与applet通信,从server端取时间，然后显示到客户端！

import java.awt.Graphics;
import java.util.*;
import java.text.DateFormat;
import java.applet.Applet;public class Clock extends Applet implements Runnable {
    private Thread clockThread = null;
    public void start() {
        if (clockThread == null) {
            clockThread = new Thread(this, "Clock");
            clockThread.start();
        }
    }
    public void run() {
        Thread myThread = Thread.currentThread();
        while (clockThread == myThread) {
            repaint();
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e){
            // the VM doesn't want us to sleep anymore,
            // so get back to work
            }
        }
    }
    public void paint(Graphics g) {
        // get the time and convert it to a date
        Calendar cal = Calendar.getInstance();
        Date date = cal.getTime();
        // format it and display it
        DateFormat dateFormatter = DateFormat.getTimeInstance();
        g.drawString(dateFormatter.format(date), 5, 10);
    }
    // overrides Applet's stop method, not Thread's
    public void stop() {
        clockThread = null;
    }
}
java tutorial上抄的

同意：　rinehart(rinehart)　的看法首先建立连接，然后从服务器端取得值传到客户端进行显示。我才想通的。

rinehart(rinehart) ：你有没有更详细点的说明
jsyx()　：你的作法好像只能显示客户端的时间

从applet里面建立一个udp向服务器的13号端口发送请求，就能获得server的时间了。
（13号端口是时间服务端口）

blueHand兄，有没有更具体的例程

开启Web server 的时钟服务服务/协议端口说明
daytime 13 时钟服务，返回当前服务器时间的文本描述。 import java.io.*;
import java.net.*;public class DaytimeTCPClient
{    public static final String NETASCIIEOL = "\r\n";
    private static final SocketFactory DEFAULTSOCKETFACTORY = new DefaultSocketFactory();
    protected int timeout;                    //超时时间
    protected Socket socket;
    protected boolean isConnected;            //连接标志
    protected int defaultPort;                //默认端口号
    protected InputStream input;              //Socket的输入流
    protected OutputStream output;            //Socket的输出流
    protected SocketFactory socketFactory;    //SocketFactory是Socket抽象类    public static final int DEFAULTPORT = 13;
    private char buffer[];    public DaytimeTCPClient()
    {
        socket = null;
        input = null;
        output = null;
        timeout = 0;
        defaultPort = 0;
        isConnected = false;
        socketFactory = DEFAULTSOCKETFACTORY;        buffer = new char[64];
        setDefaultPort(13);
    }    public String getTime()
        throws IOException
    {
        StringBuffer stringbuffer = new StringBuffer(buffer.length);
        BufferedReader bufferedreader = new BufferedReader(new InputStreamReader(input));
        do
        {
            int i = bufferedreader.read(buffer, 0, buffer.length);
            if(i > 0)
                stringbuffer.append(buffer, 0, i);
            else
                return stringbuffer.toString();
        } while(true);
    }
    protected void connectAction()
        throws IOException
    {
        socket.setSoTimeout(timeout);
        input = socket.getInputStream();
        output = socket.getOutputStream();
        isConnected = true;
    }    public void connect(InetAddress inetaddress, int i)
        throws SocketException, IOException
    {
        socket = socketFactory.createSocket(inetaddress, i);
        connectAction();
    }    public void connect(String s, int i)
        throws SocketException, IOException
    {
        socket = socketFactory.createSocket(s, i);
        connectAction();
    }    public void connect(InetAddress inetaddress, int i, InetAddress inetaddress1, int j)
        throws SocketException, IOException
    {
        socket = socketFactory.createSocket(inetaddress, i, inetaddress1, j);
        connectAction();
    }    public void connect(String s, int i, InetAddress inetaddress, int j)
        throws SocketException, IOException
    {
        socket = socketFactory.createSocket(s, i, inetaddress, j);
        connectAction();
    }    public void connect(InetAddress inetaddress)
        throws SocketException, IOException
    {
        connect(inetaddress, defaultPort);
    }    public void connect(String s)
        throws SocketException, IOException
    {
        connect(s, defaultPort);
    }    public void disconnect()
        throws IOException
    {
        socket.close();
        input.close();
        output.close();
        socket = null;
        input = null;
        output = null;
        isConnected = false;
    }    public boolean isConnected()
    {
        return isConnected;
    }    public void setDefaultPort(int i)
    {
        defaultPort = i;
    }    public int getDefaultPort()
    {
        return defaultPort;
    }    public void setDefaultTimeout(int i)
    {
        timeout = i;
    }    public int getDefaultTimeout()
    {
        return timeout;
    }    public void setSoTimeout(int i)
        throws SocketException
    {
        socket.setSoTimeout(i);
    }    public int getSoTimeout()
        throws SocketException
    {
        return socket.getSoTimeout();
    }    public void setTcpNoDelay(boolean flag)
        throws SocketException
    {
        socket.setTcpNoDelay(flag);
    }    public boolean getTcpNoDelay()
        throws SocketException
    {
        return socket.getTcpNoDelay();
    }    public void setSoLinger(boolean flag, int i)
        throws SocketException
    {
        socket.setSoLinger(flag, i);
    }    public int getSoLinger()
        throws SocketException
    {
        return socket.getSoLinger();
    }    public int getLocalPort()
    {
        return socket.getLocalPort();
    }    public InetAddress getLocalAddress()
    {
        return socket.getLocalAddress();
    }    public int getRemotePort()
    {
        return socket.getPort();
    }    public InetAddress getRemoteAddress()
    {
        return socket.getInetAddress();
    }    public boolean verifyRemote(Socket socket)
    {
        InetAddress inetaddress = socket.getInetAddress();
        InetAddress inetaddress1 = getRemoteAddress();
        return inetaddress.equals(inetaddress1);
    }    public void setSocketFactory(SocketFactory socketfactory)
    {
        if(socketfactory == null)
        {
            socketFactory = DEFAULTSOCKETFACTORY;
            return;
        } else
        {
            socketFactory = socketfactory;
            return;
        }
    }
}

你可以参考《java 2编程详解》，里面有udp方式实现获取远程主机时间的例子。如果你用tcp来实时显示时间，我想主机性能将大幅度下降。

to Lusxiao: 能把例程粘贴出来吗

不是很急，但最好是java applet形式的程序

还有个问题，如何开启windows2000下的 Web server 的时钟服务

你需要安装Simple TCP/IP services ,缺省是不装的。

TO lusxiao : 不是说应当用udp方式获取远程主机时间，为何要安装simple tcp/ip services

你问我windows2000下的时钟服务在Simple TCP/IP services 下面，但我没用过不知道是不是udp的.

Daytime协议
有一个有用的调试工具就是daytime服务。它的作用就是返回当前时间和日期，格式是字符串格式。基于TCP的daytime服务
daytime服务是基于TCP的应用，服务器在TCP端口13侦听，一旦有连接建立就返回ASCII形式的日期和时间，在传送完后关闭连接。接收到的数据被忽略。基于UDP的daytime服务
daytime服务也可以使用UDP协议，它的端口也是13，不过UDP是用数据报传送当前时间的。接收到的数据被忽略。Daytime格式
对于daytime没有特定的格式，建议使用ASCII可打印字符，空格和回车换行符。daytime应该在一行上。下面是两种流行的格式：Weekday, Month Day, Year Time-Zone
例子：Tuesday, February 22, 1982 17:37:43-PST和用于SMTP中的格式：dd mmm yy hh:mm:ss zzz
例子：02 FEB 82 07:59:01 PST

lionhero：我改了一下
你可以用这个看看，但你还是要作修改，我要下班了。byebyepackage daytimeclient;import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.io.*;
import java.net.*;/**
* Title:        DaytimeClient
* Description:
* Copyright:    Copyright (c) 2001
* Company:      Huateng
* @author lu shengxiao
* @version 1.0
*/public class DayTimeClient extends Applet {
  private static final int TIME_PORT=13;
  private static final int TIMEOUT=10000;
  private DatagramSocket timeSocket=null;
  private static final int SMALL_ARRAY=1;
  private static final int TIME_ARRAY=100;
  InetAddress remoteMachine;
  private String timeString;
  private Label lblDayTime = new Label();   /**Start the applet*/
  public void start() {
    try{
      timeSocket=new DatagramSocket();
    }catch(SocketException e){
      System.err.println("Unable to open socket:"+e);
    }
    try{
      remoteMachine=InetAddress.getByName("HOSTNAME");
    }catch(UnknownHostException uhe){
      System.out.println("Unknown host"+remoteMachine+":"+uhe);
    }
    getDayTime();
  }  public String getDayTime(){
    DatagramPacket timeQuery;
    DatagramPacket response;
    byte[] emptyBuffer;
    try{
      emptyBuffer=new byte[SMALL_ARRAY];
      timeQuery=new DatagramPacket(emptyBuffer,emptyBuffer.length,remoteMachine,TIME_PORT);
      timeSocket.send(timeQuery);
    }catch(IOException e){
      System.out.println("Unable to send to"+remoteMachine+":"+e);
    }    try {
      timeSocket.setSoTimeout(TIMEOUT);
    }catch (SocketException ex) {}
    try{
      emptyBuffer=new byte[TIME_ARRAY];
      response=new DatagramPacket(emptyBuffer,emptyBuffer.length);
      timeSocket.receive(response);
      timeString=new String(response.getData());
      lblDayTime.setText(timeString);
    }catch(InterruptedIOException iie){
      System.out.println("Timeout on receive:"+iie);
    }catch(IOException ioe){
      System.out.println("Failed I/O:"+ioe);
    }
    return timeString;
  }  /**Stop the applet*/
  public void stop() {
    if (timeSocket!=null) timeSocket.close();
  }  public DayTimeClient() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  private void jbInit() throws Exception {
    lblDayTime.setText("label1");
    this.add(lblDayTime, null);
  }}

谢谢 lusxiao, 还有我想请问一下
装好 simple tcp/ip service 后date time 服务自动就开启了
并且同时包括 tcp 和 udp 两种协议方式

应该是这样的。
参考楼上RedGuest(Haha)的解答
我上面的程序只能得到一次时间，你要把它改成每隔一秒循环一次的。

调试易

高分，不够再加！！如何用java applet实现在客户端浏览器中显示即时的web server的系统时间

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