udpserverdemo.java

学习参考,java基本语法练习,包括一些常用的技巧

//基于UDP的服务器端程序演示
import java.net.*;
import java.io.*;
import java.util.*;
public class UDPServerDemo
{
	static final int PORT = 4000;//设置服务端口
 	private byte[] buf = new byte[1000];
 	private DatagramPacket dgp =new  DatagramPacket(buf,buf.length);
 	private DatagramSocket sk;
 	public UDPServerDemo()
 	{
 		try
 		{
 			//实例化数据报
     		sk = new DatagramSocket(PORT);
     		System.out.println("Server start......");
     		while(true)
     		{
       			//等待接收
       			sk.receive(dgp);
       			//获取接收信息
       			String strReceived =  "("+ dgp.getAddress()+": "+ dgp.getPort()+")"+new String(dgp.getData(),0,dgp.getLength());
       			System.out.println(strReceived);
       			String strOutMess ="";  
        		//读取输入
         		BufferedReader stdin  = new BufferedReader(new InputStreamReader(System.in));
         		try
         		{
           			strOutMess = stdin.readLine();
	         	}catch(IOException ie)
	         	{
           			System.err.println("输入输出错误!");
         		}
       			String strOutput = "[Server say]: "+ strOutMess;
       			//拷贝字符到缓存
       			byte[] buf = strOutput.getBytes();
       			//打包数据，发送回信息。
       			DatagramPacket out = new DatagramPacket(buf,buf.length,dgp.getAddress(),dgp.getPort());
       			sk.send(out);
     		}
    }catch(SocketException e)
    {
		System.err.println("打开套接字错误!");
		System.exit(1);
    }catch(IOException e)
    {
		System.err.println("数据传输错误!");
		e.printStackTrace();
		System.exit(1);
    }
 }
 public static void main(String[] args)
 {
	new UDPServerDemo();
 }
}