notepad.java

java编写的记事本程序

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

public class notepad extends Frame implements ActionListener
{
	/***************视图设计***************/
	MenuBar mb=new MenuBar();
	Menu m1=new Menu("File");
	MenuItem mi1=new MenuItem("New");
	MenuItem mi2=new MenuItem("Load");
	MenuItem mi3=new MenuItem("Save");
	MenuItem mi4=new MenuItem("Save As");
	MenuItem mi5=new MenuItem("Quit");
	Menu m2=new Menu("Edit");
	Menu m3=new Menu("About");
	TextArea t=new TextArea();
	
	/***************变量定义****************/
	String FileName="";
	String FileDirectory="/";
	int save=0;    //0未保存，1保存
	
	public notepad()
	{
		super("记事本");
		setSize(500,500);
		mi1.addActionListener(this);
		mi2.addActionListener(this);
		mi3.addActionListener(this);
		mi4.addActionListener(this);
		mi5.addActionListener(this);
		m1.add(mi1);
		m1.add(mi2);
		m1.add(mi3);
		m1.add(mi4);
		m1.add(mi5);
		mb.add(m1);
		mb.add(m2);
		mb.add(m3);
		m2.addActionListener(this);
		m3.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent Event)
			{
				System.exit(0);
			}
		});
		setMenuBar(mb);
		setVisible(true);
		add(t);
	}
	public void actionPerformed(ActionEvent evt)
	{
		char msg=evt.getActionCommand().charAt(0);
		switch(msg)
		{
			case 'N':newFile();break;
			case 'L':loadFile();break;
			case 'S':if(evt.getActionCommand().length()==4)saveFile();
			         else saveAsFile();
			         break;
			case 'A':System.exit(0);break;
			case 'E':break;
			case 'Q':isSavedAndExit();			
			         System.exit(0); 
			         break;
		}
		
	}
	
	/***************创建新文件****************/
	public void newFile()
	{
		FileName="";
		FileDirectory="/";
		t.setText("");	
	}
	
  /****************载入文件****************/
	public void loadFile()
	{
		Frame loadframe=new Frame();
		FileDialog d=new FileDialog(loadframe,"Load File",FileDialog.LOAD);
		d.setVisible(true);
		try
		{
			FileReader fr=new FileReader(d.getDirectory()+d.getFile());
			FileName=d.getFile();
			FileDirectory=d.getDirectory();
		  BufferedReader br=new BufferedReader(fr);
		  String line=br.readLine();
		  t.setText("");
		  while(line!=null)
		  {
		  	t.append(line);
		  	t.append("\n");
		  	line=br.readLine();
		  }
		  br.close();  
		}
		catch(Exception e)
		{
			System.out.println(e);
		}
	}
	
	/**************保存文件****************/
	public void saveFile()
	{
		if(FileName.length()==0)
		{
			Frame saveframe=new Frame();
			FileDialog d=new FileDialog(saveframe,"Save File",FileDialog.SAVE);
			d.setVisible(true);
			FileName=d.getFile();
			FileDirectory=d.getDirectory();
		}
		try
		{
			FileOutputStream fo=new FileOutputStream(FileDirectory+FileName);
			DataOutputStream dos=new DataOutputStream(fo);
			byte[] b=t.getText().getBytes();
			dos.write(b);
			fo.close();
		}
		catch(Exception e)
		{
			System.out.println(e);
		}
	  
	}
	/**************文件另存为******************/
	public void saveAsFile()
	{
		FileName="";
		saveFile();
	}
	
	/*************退出程序判断文件是否保存的确认对话框************/
	public void isSavedAndExit()
	{
		if(save==1)System.exit(0);
		else 
		{
			
		}
	}
	
	public static void main(String[] args)
	{
		notepad n=new notepad();
		n.setVisible(true);
		n.addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				//*************判断文件是否保存****************//
				System.exit(0);
			}
		});
	}
}