import java.awt.event.*;
import java.net.*;
import javax.swing.*;

public class UDPClientDemo extends JFrame{
	String host="localhost"; //服務器地址
	int port=2345; //端口號
	
	public UDPClientDemo(){
		try{		
			DatagramSocket socket=new DatagramSocket(); //實例化一個數據報Socket
			InetAddress address=InetAddress.getByName(host);  //服務器地址
			byte[] buffer=new byte[256]; //緩沖區
			DatagramPacket packet=new DatagramPacket(buffer,buffer.length,address,port); //實例化一個數據報
			socket.send(packet); //發送報文
			
			packet=new DatagramPacket(buffer,buffer.length); 
			socket.receive(packet); //接受回應
			
			String message=new String(packet.getData()); //得到報文信息
			System.out.println("Received from: "+packet.getAddress()); //顯示信息源地址
			System.out.println(message); //顯示服務器返回信息
			
			socket.close(); //關閉端口
		}
		catch (Exception ex){
			ex.printStackTrace(); //輸出出錯信息
		}		
	}
	
	public static void main(String[] args){
		new UDPClientDemo();
	}
}