这个是服务器 import java.awt.*; import java.awt.event.*; import java.net.*; import javax.swing.*; public class UDPServerDemo extends JFrame{ int port=2345; //端口号 public UDPServerDemo(){ try{ byte[] buffer=new byte[256]; //缓冲区数组 DatagramSocket socket=new DatagramSocket(port); //实例化数据报Socket DatagramPacket packet; System.out.println("Server start..."); //输出运行信息 while (true){ packet=new DatagramPacket(buffer,buffer.length); //实例化数据报 socket.receive(packet); //接受请求 InetAddress target=packet.getAddress(); System.out.println("Received from"+target); //输出请求地址 int port=packet.getPort(); //得到接收端口 byte[] message="This is server,Who are you?".getBytes(); //服务器返回信息 packet=new DatagramPacket(message,message.length,target,port); //实例化数据报 socket.send(packet); //发送数据报 } } catch (Exception ex){ ex.printStackTrace(); //输出出错信息 } } public static void main(String[] args){ new UDPServerDemo(); } }