用java写的一个简易记事本

import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class NoteDemo {

	private Frame fr;
	private TextArea ta;
	private MenuBar bar;
	private Menu m;
	private MenuItem mi1,mi2,mi3,mi4,mi5;
	private Font font;
	private Dialog dia;
	private Button but1,but2;

	private FileDialog fd1,fd2;

	private File file = null;

	NoteDemo()
	{
		init();
	}

	public void init()
	{
		fr = new Frame("MyNote   by__sho");
		ta = new TextArea();
		bar = new MenuBar();
		m = new Menu("File");
		mi1 = new MenuItem("New");
		mi2 = new MenuItem("Open");
		mi3 = new MenuItem("Save");
		mi4 = new MenuItem("Save As");
		mi5 = new MenuItem("Exit");

		but1 = new Button("是");
		but2 = new Button("否");

		fd1 = new FileDialog(fr,"File",FileDialog.LOAD );
		fd2 = new FileDialog(fr,"File",FileDialog.SAVE );

		font = new Font("Monospaced" ,Font.BOLD,20);//新建一个字体对象

		dia = new Dialog(fr,"是否保存？",true);

		dia.setLayout(new FlowLayout());
		dia.setBounds(530, 280, 140, 100);	

		fr.setBounds(200, 80, 700, 600);
		fr.add(ta);
		fr.setFont(font);//设置字体

		m.add(mi1);
		m.add(mi2);
		m.add(mi3);
		m.add(mi4);
		m.add(mi5);
		bar.add(m);

		fr.setMenuBar(bar);

		dia.add(but1);
		dia.add(but2);

		myEvent();

		fr.setVisible(true);

	}

	public void myEvent()
	{
		fr.addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				System.exit(0);
			}
		});
		//New
		mi1.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				ta.setText("");
			}
		});
		//Open
		mi2.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				fd1.setVisible(true);
				String dirPath = fd1.getDirectory();//返回次对话框的目录
				String fileName = fd1.getFile();//获取此文件对话框的选定文件
				if(dirPath==null&&fileName==null)
					return ;//下面的程序不运行
				ta.setText("");
				file = new File(dirPath,fileName);
				try
				{
					BufferedReader bufr = new BufferedReader(new FileReader(file));
					String str = null;
					while((str = bufr.readLine())!=null)
					{
						ta.append(str +"\r\n");
					}
					bufr.close();//资源必须关闭
				}
				catch(IOException ex)
				{
					throw new RuntimeException("流无法读取");
				}
			}
		});
		//Save
		mi3.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				saveMethod();
			}
		});
		mi4.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				fd2.setVisible(true);
				String dirPath = fd2.getDirectory();//返回次对话框的目录
				String fileName = fd2.getFile();//获取此文件对话框的选定文件
				if(dirPath==null&&fileName==null)//判断是否取消
					return ;//下面的程序不运行
//				ta.setText(" ");
				file = new File(dirPath,fileName);

				try
				{
					BufferedWriter bufw = new BufferedWriter(new FileWriter(file));
					String str = ta.getText();
					bufw.write(str);
					bufw.close();
				}
				catch(IOException ed)
				{
					throw new RuntimeException("写入流出现异常");
				}
			}
		});
		//Exit
		mi5.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				String str = ta.getText();
				if(str.equals(""))
					System.exit(0);
				else
				{
					dia.setVisible(true);
				}
			}
		});

		but1.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				saveMethod();
			}
		});

		but2.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				System.exit(0);
			}
		});

		ta.addKeyListener(new KeyAdapter()
		{
			public void keyPressed(KeyEvent e)
			{
//				ctrl和S同时按下
				if((e.isControlDown())&&(e.getKeyCode() == e.VK_S))
				{
					saveMethod();
				}
			}
		});
	}

	public void saveMethod()
	{
		if(file==null)
		{
			//文件为空，那么文件对话框就会跳出来
			fd2.setVisible(true);
			String dirPath = fd2.getDirectory();//返回次对话框的目录
			String fileName = fd2.getFile();//获取此文件对话框的选定文件
			if(dirPath==null&&fileName==null)//判断是否取消
				return ;//下面的程序不运行
//			ta.setText(" ");
			file = new File(dirPath,fileName);
		}

		try
		{
			BufferedWriter bufw = new BufferedWriter(new FileWriter(file));
			String str = ta.getText();
			bufw.write(str);
			bufw.close();
		}
		catch(IOException ed)
		{
			throw new RuntimeException("写入流出现异常");
		}
	}

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