记事本 程序（52-79行需细读）

import java.awt.*;
import java.awt.event.*;
import java.io.*;
class LL 
{
	private Frame f;
	private MenuBar mb;
	private Menu m,m2;
	private MenuItem mi,mi2,open,save;
	private FileDialog diaOpen,diaClose;
	private TextArea ta;
	private File file;

	LL() 
	{
		init();
	}
	public void init() 
	{
		f=new Frame("我是窗体");
		mb=new MenuBar();
		m=new Menu("文件");
		mi=new MenuItem("关闭");
		m2=new Menu("xin jia ru");
		mi2=new MenuItem("zi lei mu o");
		open=new MenuItem("打开");
		save=new MenuItem("保存");
		diaOpen=new FileDialog(f,"wo yao da kai o",FileDialog.LOAD);
		diaClose=new FileDialog(f,"wo yao bao cun",FileDialog.SAVE);
		ta=new TextArea();


		f.setBounds(300,300,400,300);
		f.setMenuBar(mb);
		
		mb.add(m);
	
		m.add(open);
		m.add(save);
		m.add(mi);
		
		m.add(m2);
		m2.add(mi2);

		myEvent();
		f.add(ta);
		f.setVisible(true);
	}

	public void myEvent() 
	{
		save.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				if(file==null)
				{
					diaClose.setVisible(true);
					String dirPath=diaClose.getDirectory();
					String fileName=diaClose.getFile();
					if(dirPath==null||fileName==null)
					{
						return;
					}
					file=new File(dirPath,fileName);
				}
				try
				{
					BufferedWriter bw=new BufferedWriter(new FileWriter(file));
					String text=ta.getText();
					bw.write(text);
					bw.close();
				}
				catch (IOException m)
				{
					throw new RuntimeException();
				}
			}
		});
		open.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent a) 
			{
				diaOpen.setVisible(true);
				try
				{
					String fileDir=diaOpen.getDirectory();
					String fileName=diaOpen.getFile();
					if(fileDir==null||fileName==null)
						return;
					file=new File(fileDir,fileName);
					
					BufferedReader br=new BufferedReader
						(new FileReader(file));
					String line=null;
					while((line=br.readLine())!=null)
					{
					//String text=br.readLine();
					ta.append(line+"\r\n");
					}
				}
				catch (IOException e)
				{
					throw new RuntimeException("你搞什么。");
				}
				
			}
		});
		f.addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent a)
			{
				System.exit(0);
			}
		});
        
		mi.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent a)
			{
				System.exit(0);
			}
		});

	}
	public static void main(String[] args) 
	{
		new LL();
	}
}