给出一个实例即可：

package mymenu;

import java.awt.*;

import java.awt.event.*;

import java.io.*;

public class MyMenuTest

{

private Frame f;

private MenuBar bar;

private TextArea ta;

private Menu fileMenu;

private MenuItem openItem,saveItem,closeItem;

private FileDialog openDia,saveDia;

private File file;

MyMenuTest()

{

init();

}

public void init()

{

f = new Frame("my window");

f.setBounds(300,100,650,600);

bar = new MenuBar();

ta = new TextArea();

fileMenu = new Menu("文件");

openItem = new MenuItem("打开");

saveItem = new MenuItem("保存");

closeItem = new MenuItem("退出");

fileMenu.add(openItem);

fileMenu.add(saveItem);

fileMenu.add(closeItem);

bar.add(fileMenu);

f.setMenuBar(bar);

openDia = new FileDialog(f,"我要打开",FileDialog.LOAD);

saveDia = new FileDialog(f,"我要保存",FileDialog.SAVE);

f.add(ta);

myEvent();

f.setVisible(true);

}

private void myEvent()

{

saveItem.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

if(file==null)

{

saveDia.setVisible(true);

String dirPath = saveDia.getDirectory();

String fileName = saveDia.getFile();

if(dirPath==null || fileName==null)

return ;

file = new File(dirPath,fileName);

}

try

{

BufferedWriter bufw = new BufferedWriter(new FileWriter(file));

String text = ta.getText();

bufw.write(text);

//bufw.flush();

bufw.close();

}

catch (IOException ex)

{

throw new RuntimeException();

}

}

});

openItem.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

openDia.setVisible(true);

String dirPath = openDia.getDirectory();

String fileName = openDia.getFile();

// System.out.println(dirPath+"..."+fileName);

if(dirPath==null || fileName==null)

return ;

ta.setText("");

file = new File(dirPath,fileName);

try

{

BufferedReader bufr = new BufferedReader(new FileReader(file));

String line = null;

while((line=bufr.readLine())!=null)

{

ta.append(line+"\r\n");

}

bufr.close();

}

catch (IOException ex)

{

throw new RuntimeException("读取失败");

}

}

});

closeItem.addActionListener(new ActionListener()

{

public void actionPerformed(ActionEvent e)

{

System.exit(0);

}

});

f.addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

});

}

public static void main(String[] args)

{

new MyMenuTest();

}

}