serverapp_udp.java

这个是一个由客户端和服务端程序的UDP通信的Java应用程序

//Arial Black NARROW   
//Serverapp_UDP.java
import  java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;

public class Serverapp_UDP  extends WindowAdapter implements ActionListener,KeyListener
{
	TextField str_send;
  Label label;
  TextArea msg; 
  Button send,exit;
  Panel pl;

  String hostname;
  DatagramSocket receiveSocket,sendSocket;
  DatagramPacket receivePacket,sendPacket;

  public void display()
  {
   Frame f= new Frame("在线聊天---服务器");
   f.setSize(400,350);
   f.setLocation(400,350);
   f.setBackground(Color.red);
   pl=new Panel();
   f.add(pl,"South");
   msg= new TextArea();
   msg.setSize(100,250);

   msg.setBackground(Color.white);
   msg.setEditable(false);
   f.add(msg);
   label = new Label ("发送消息");
   pl.add(label);
   str_send = new TextField(20);
   pl.add(str_send);
   str_send.addKeyListener(this);
   send = new Button("发送");
   pl.add(send);
   str_send.addActionListener(this);
   exit = new Button("退出");
   pl.add(exit);
   exit.addActionListener(this);
   f.addWindowListener(this);
   f.setVisible(true);

   try
   {
     //sendSocket = new DatagramSocket(5000);
     sendSocket = new DatagramSocket();
   }
   catch(Exception e)
    {
      msg.append(e + "\n");
    }
  }

    public void receiveMessage()
    {
      try
      {
         receiveSocket = new DatagramSocket(3333);
         while(true)
         {
           byte[] buf = new byte[500];
           receivePacket = new DatagramPacket(buf, buf.length);
          // receivePacket = new DatagramPacket(buf, buf.length);//----//?????
           receiveSocket.receive(receivePacket);
           if(receivePacket.getLength()==0)
            {
               System.out.println("The Message Is Blank,please type it again!!");
               continue;
            }
            ByteArrayInputStream bin = new ByteArrayInputStream(receivePacket.getData());
            BufferedReader reader = new BufferedReader (new InputStreamReader(bin));
            msg.append("Client:"+reader.readLine());
            msg.append("\n");
            bin.close();
         }
       }
       catch(Exception  e)
       {
       	msg.append(e+"\n");
       	}
    }


     public void sendMessage()
     {
       try
        {
           String s = str_send.getText();
           str_send.setText(" ");
           msg.append("Server:" +s+"\n");
           ByteArrayOutputStream out = new ByteArrayOutputStream();
           PrintStream pout = new PrintStream(out);
           pout.print(s);
           byte buf[]= out .toByteArray();
           sendPacket = new DatagramPacket(buf,buf.length,InetAddress.getByName(hostname),3001);
           sendSocket.send(sendPacket);
           buf = null;
        }
         catch(Exception err)
          {
             msg.append(err+ "\n");
          }
    }

     public void actionPerformed(ActionEvent e )
     {
       if(e.getSource()==send)
        {
            sendMessage();
        } 
       if(e.getSource()==exit)
        {
          System.out.println("聊天程序已关闭，再见！\n");
          System.exit(0);
        }
      }

       public void keyPressed(KeyEvent e)
        {
           if(e.getSource() == str_send)
             {
                if(e.getKeyChar()==KeyEvent.VK_ENTER)
                 {
                    sendMessage();
                 }
             }
        }

    public  void  windowClosing(WindowEvent  e)
    {
     System.out.println("聊天程序已关闭，再见！\n");
          System.exit(0);
    	}

      public static void main(String arg[])
       {
         Serverapp_UDP app = new Serverapp_UDP();
         app.display();
         app.receiveMessage();
       }
      public void keyTyped(KeyEvent e){}
      public void keyReleased(KeyEvent e){}
}