notepad.java

用java编写的一个记事本的小程序.主要用到j2se中awt

import java.awt.*;
import java.awt.event.*;
import java.io.*;
/*
 *@author lin
 */
public class Notepad extends Frame
{
	private MenuBar mb;//工具栏
	private Menu m1;
	private Menu m2;
	private MenuItem mi1,mi2,mi3,mi4,mi5;
	//右键菜单
	private PopupMenu pm;
	private MenuItem pm1,pm2,pm3;

	//文本域
	private TextArea ta;
	Dialog d;

	public Notepad(){
	  super("记事本");
	  setLayout(new BorderLayout());

	  mb = new MenuBar();
	  m1 = new Menu("文件");
	  m2 = new Menu("关于");
	  mi1 = new MenuItem("新建");
	  mi2 = new MenuItem("打开");
	  mi3 = new MenuItem("保存");
	  mi4 = new MenuItem("退出");
	  mi5 = new MenuItem("关于");
	  m1.add(mi1);
	  m1.add(mi2);
	  m1.add(mi3);
	  m1.add(mi4);
	  m2.add(mi5);
	  mb.add(m1);
	  mb.add(m2);
	  //右键菜单
	  pm = new PopupMenu();
	  pm1 = new MenuItem("粘贴");
	  pm2 = new MenuItem("复制");
	  pm3 = new MenuItem("剪切");
	  pm.add(pm1);
	  pm.addSeparator();
	  pm.add(pm2);
	  pm.addSeparator();
	  pm.add(pm3);
	  pm.addSeparator();
	  //文本域
	  ta = new TextArea();
	  
	  enableEvents(AWTEvent.MOUSE_EVENT_MASK);

	  setMenuBar(mb);
	  
	  add(ta,BorderLayout.CENTER);
	  ta.add(pm);
	  setSize(600,800);
	  setVisible(true);

	  addWindowListener(new WindowAdapter(){
	    public void windowClosing(WindowEvent e){
		  System.exit(0);
		}
	  });
	  //消息框
	  d = new Dialog(new Frame(),"Welcome!");
	  d.setLayout(new GridLayout(2,1));
	  Label msg = new Label("大家一起交流");
	  d.add(msg);
	  d.pack();
	  d.addWindowListener(new WindowAdapter(){
			  public void windowClosing(WindowEvent e){
			    d.setVisible(false);
			  }
			});

	  //监听事件
	  ta.addMouseListener(new MouseAdapter(){
		public void mouseReleased(MouseEvent e){
		  if(e.isPopupTrigger()){
			pm.show(e.getComponent(),e.getX(),e.getY());
		  }
		}
	  });
	  mi1.addActionListener(new ButtonListener());
	  mi2.addActionListener(new ButtonListener());
	  mi3.addActionListener(new ButtonListener());
	  mi4.addActionListener(new ButtonListener());
	  mi5.addActionListener(new ButtonListener());
	  /*pm1.addActionListener(new ButtonListener());
	  pm2.addActionListener(new ButtonListener());
	  pm3.addActionListener(new ButtonListener());*/
	}
	public void processMouseEvent(MouseEvent e){
	  if(e.isPopupTrigger()){
	    pm.show(e.getComponent(),e.getX(),e.getY());
	  }
	}

	class ButtonListener implements ActionListener
	{
		public void actionPerformed(ActionEvent e){
		  //新建
		  if(e.getSource()==mi1){
			ta.setText("");
		  }
		  //打开文件
		  if(e.getSource()==mi2){
		    FileDialog fd = new FileDialog(new Frame(),"打开文件");
			fd.setVisible(true);
			String fileName = fd.getDirectory()+"/"+fd.getFile();
			try
			{
				String content;
				FileReader fr = new FileReader(fileName);
				BufferedReader br = new BufferedReader(fr);
				while((content=br.readLine())!=null){
					ta.append(content+"\n");
				}			
				br.close();
				fr.close();
			}
			catch (Exception ioe)
			{
				System.out.println("读取文件错误！");
			}
			
		  }

		  //保存文件
		  if(e.getSource()==mi3){
		    FileDialog fd = new FileDialog(new Frame(),"保存文件",FileDialog.SAVE);
			fd.setVisible(true);
			String fileName = fd.getDirectory()+"/"+fd.getFile()+".txt";
			try
			{
				FileWriter fw = new FileWriter(fileName);
				PrintWriter pw = new PrintWriter(fw);
				pw.print(ta.getText());
				pw.close();
				fw.close();
			}
			catch (Exception ioe)
			{
				ioe.printStackTrace();
			}
		  }

		  //退出
		  if(e.getSource()==mi4){
		    System.exit(0);
		  }
		  if(e.getSource()==mi5){
		    d.setVisible(true);
		  }
		}
	}

	public static void main(String[] args){
	  Notepad n = new Notepad();
	}
}