gbnserver.java

网络实验：用JAVA语言实现电子邮件的发送功能！有图形界面。

import java.io.*;
import java.net.*;

public class GBNServer
{
	public void go() throws IOException
	{
		DatagramSocket datagramSocket = new DatagramSocket(4567);;
		DatagramPacket inDataPacket;
		DatagramPacket outDataPacket;
		InetAddress clientAddress;
		int clientPort;
		byte[] msg = new byte[10];
		String count= "";
		String rec = "";
		int c = 0;
		
		System.out.println("UDP server active on port 4567");
		while(true)
		{
			if((count.equals("0")) && (c == 0))
			{
				c = 1;
				//t = 1;
				inDataPacket = new DatagramPacket(msg,msg.length);
				datagramSocket.receive(inDataPacket);
				rec = new String(inDataPacket.getData(),0,inDataPacket.getLength());
				//System.out.println(rec.substring(1));
				count = rec.substring(0,1);
			}
			/*else if((count.equals("2")) && (t == 1))
			{
				t = 2;
				inDataPacket = new DatagramPacket(msg,msg.length);
				datagramSocket.receive(inDataPacket);
				rec = new String(inDataPacket.getData(),0,inDataPacket.getLength());
				count = rec.substring(0,1);
			}*/
			else
			{
			inDataPacket = new DatagramPacket(msg,msg.length);
			datagramSocket.receive(inDataPacket);
			rec = new String(inDataPacket.getData(),0,inDataPacket.getLength());
			if(rec.equals("complete"))
				break;
			System.out.println(rec.substring(1));
			count = rec.substring(0,1);
			clientAddress = inDataPacket.getAddress();
			clientPort = inDataPacket.getPort();
			outDataPacket = new DatagramPacket(count.getBytes(),count.getBytes().length,clientAddress,clientPort);
			datagramSocket.send(outDataPacket);}
		}
	}
	public static void main(String[] args) throws IOException
	{
		GBNServer gbn = new GBNServer();
		gbn.go();
	}
}