package UDP_chat;

import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.List;
import java.awt.Panel;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

 class Chat extends Frame {
    List lst = new List(6);
	TextField tfIP = new TextField(15);
	TextField tfData = new TextField(20);
	DatagramSocket ds = null;
	public List setLst(String item,int index){
		lst.add(item, index);
		return lst;
	}
	//建構函式裡面實現視窗初始化、接收資訊（執行緒）、傳送資訊
	public Chat(){
		try{
			ds = new DatagramSocket(3000);
		}catch(Exception e){
			e.printStackTrace();
		}
		this.add(lst,"Center");
		Panel p = new Panel();
		this.add(p,"South");
		
		p.setLayout(new BorderLayout());
		p.add(tfIP,"West");
		p.add(tfData,"East");
		//接收資訊：建立一個執行緒，一直在接收資訊
		new Thread(new Runnable(){
			public void run(){
				byte[] buf = new byte[1024];
				DatagramPacket dp = new DatagramPacket(buf,1024);
				//迴圈接收資訊
				while(true){
					try{
						ds.receive(dp);
						String haha = "訊息："+new String(dp.getData(),0,dp.getLength())
										+" from "+dp.getAddress().getHostAddress()
										+":"+dp.getPort();
						//將接收的資訊列印到資訊欄
						lst.add(haha,0);
					}catch(Exception e){
						//ds沒有關閉才執行丟擲異常
						if(!ds.isClosed()){
							e.printStackTrace();
						}
					}
				}
			}
		}).start();
		
		//傳送訊息：訊息資訊點回車，觸發事件
		tfData.addActionListener(new ActionListener(){
			//需要實現此方法
			public void actionPerformed(ActionEvent e){
				byte [] buf;
				//獲取訊息資訊
				buf = tfData.getText().getBytes();
				
				try{
					//組裝訊息內容
					DatagramPacket dp= new DatagramPacket(buf,buf.length,
							InetAddress.getByName(tfIP.getText()),3000);
					//傳送訊息
					ds.send(dp);
				}catch(Exception ex){
					ex.printStackTrace();
				}
				tfData.setText("");
			}
		});
		//關閉視窗的觸發事件，關閉ds
		addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				ds.close();
				dispose();
				System.exit(0);
			}
		});
	}
	
	public static void main(String[] args){
		//初始化視窗
		Chat chat = new Chat();
		chat.setSize(300,400);
		chat.setTitle("即時通訊");
		chat.setVisible(true);
		chat.setResizable(false);
	}
}