udpsend.java

聊天程序实现的功能可以是像QQ聊天程序那样点对点的对话

import java.net.*;
import java.awt.*;
import java.awt.event.*;
public   class UDPSend extends Frame implements ActionListener
{ GridLayout net;
TextField textField1=new TextField();
 Button button1=new Button();
Button button2=new Button();

 public static void main(String args[])
{
UDPSend send=new UDPSend();

send.setLocation(100,100);
send.setSize(300,150);
send.show();
 
}


public  UDPSend()
{try{ 
    this.setTitle("发送数据报");
  button1.setLabel("发送");
 button2.setLabel("退出");
net=new GridLayout(3,1);
  setLayout(net);
this.add(textField1,null);
this.add(button1,null);
this.add(button2,null);
textField1.addActionListener(this); 
  button2.addActionListener(this);button1.addActionListener(this); } 
 catch(Exception e){e.printStackTrace();
}
}

void sendData()
{
    try
     {
String msg=textField1.getText();
if(msg.equals(""))
  return;
textField1.setText("");
InetAddress address=InetAddress.getByName("localhost");
int len=msg.length();
       byte[] message=new byte[len];
       msg.getBytes(0,len,message,0);
       DatagramPacket packet=new DatagramPacket(message,len,address,9999);
       DatagramSocket socket=new DatagramSocket();
       socket.send(packet);}
       
      catch(Exception e){}
     }

public void actionPerformed(ActionEvent e)
{Component com=(Component)e.getSource();
if(com.equals(button1))
   sendData();
else  if(com.equals(button2))
       System.exit(0);
      else
       sendData();
} 



}