mynote.java

简单java记事本

//package MyNote;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class MyNote extends JFrame implements ActionListener
{
	private JMenuBar menubar;
	
	private JMenu menufile;
	private JMenu menuhelp;
	private JMenu format;
	
	
	private JMenuItem openitem;
	private JMenuItem saveitem;
	private JMenuItem exititem;
	private JMenuItem aboutitem;
	
	
	private JTextArea edit;
	
		
	public MyNote()
	{
		super("MyNote");
		setLocation(200, 200);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
	
	public static void main(String[] args)
	{
		MyNote note = new MyNote();
		note.createGUI();
		note.pack();
		note.setVisible(true);	
	}
	
	private void createGUI()
	{
		edit = new JTextArea(20,40);
		JScrollPane scoll = new JScrollPane(edit);
		JPanel pane = new JPanel();
		pane.setLayout(new BorderLayout());
		
		pane.add("Center",scoll);
		this.setContentPane(pane);
		
		menubar = new JMenuBar();
		menufile = new JMenu("File");
		menuhelp = new JMenu("Help");
		
		openitem = new JMenuItem("open");
		openitem.setAccelerator(			//快捷键ctrl+o
			KeyStroke.getKeyStroke(KeyEvent.VK_O,InputEvent.CTRL_MASK));
			
		saveitem = new JMenuItem("save");
		saveitem.setAccelerator(			//快捷键
			KeyStroke.getKeyStroke(KeyEvent.VK_S,InputEvent.CTRL_MASK));
			
		exititem = new JMenuItem("exit");
		
		aboutitem= new JMenuItem("about");
				
		openitem.addActionListener(this);
		saveitem.addActionListener(this);
		exititem.addActionListener(this);
		aboutitem.addActionListener(this);
		
		
		menufile.add(openitem);
		menufile.add(saveitem);
		menufile.add(exititem);		
		menuhelp.add(aboutitem);
		
		menubar.add(menufile);
		menubar.add(menuhelp);		
		
		setJMenuBar(menubar);
	}
	public void actionPerformed(ActionEvent e)
	{
	
		Object source = e.getSource();	
		if(source == openitem)		
		{	
			openfile();
		}
		if(source == saveitem)
		{	
			savefile();
		}
		if(source==exititem)
		{
			//this.setVisible(false);
			System.exit(0);
		}
		if(source==aboutitem)
		{
			JOptionPane.showMessageDialog(null,"程波倾力打造的记事本程序");
		}
	//	fileArea.
	}

	private void openfile()
	{


		JFileChooser chooser = new JFileChooser(); 
		chooser.setCurrentDirectory(new File("."));
		chooser.setAcceptAllFileFilterUsed(false);
		 
		//显示文本文件
	  	chooser.setFileFilter(
	  	new javax.swing.filechooser.FileFilter() 
	  	{
     		 public boolean accept(File f)      //设定可用的文件的后缀名
     		 { 
        		if(f.isDirectory()||f.getName().endsWith(".txt"))
        		{
          			return true;
        	    }
        		return false;
      		}
     		public String getDescription() 
     	    {
        		return "文本文件(*.txt)";
      		}
        }
    );
    
    	//显示所有文件
        chooser.addChoosableFileFilter(
      	new javax.swing.filechooser.FileFilter() 
        {
    	   public boolean accept(File f)
    	   {
           		return true;
      	   }
    	   public String getDescription() 
    	   {
        		return "所有文件(*.*)";
     	   }
        }
    );

	
		int reply = chooser.showOpenDialog(this);
		if(reply==chooser.APPROVE_OPTION)
		{
			File selectfile=chooser.getSelectedFile();
			try
			{
				BufferedReader infile = new BufferedReader(
					new FileReader(selectfile));
				edit.setText("");
				String line;
				while((line=infile.readLine())!=null)
				{
					edit.append(line+"\n");
				}
				infile.close();
			}
			catch(IOException e)
			{
				System.out.println(e.toString());
			}
		}
		
	}
	
	
	private void savefile()
	{
		JFileChooser chooser = new JFileChooser();
		chooser.setCurrentDirectory(new File("."));
		
		//显示文本文件
	  	chooser.setFileFilter(
	  	new javax.swing.filechooser.FileFilter() 
	  	{
     		 public boolean accept(File f)      //设定可用的文件的后缀名
     		 { 
        		if(f.isDirectory()||f.getName().endsWith(".txt"))
        		{
          			return true;
        	    }
        		return false;
      		}
     		public String getDescription() 
     	    {
        		return "文本文件(*.txt)";
      		}
        }
    );
    
	    int reply = chooser.showSaveDialog(this);
		if(reply==chooser.APPROVE_OPTION)
		{
			File selectfile=chooser.getSelectedFile();
			Boolean bl=selectfile.getName().endsWith(".txt");
			if(bl==false)
		    	selectfile=new File(selectfile.getAbsolutePath()+".txt");		
			try
			{
				PrintWriter outfile = new PrintWriter(
					new FileWriter(selectfile),true);
					
				outfile.print(edit.getText());
				outfile.close();
			}
			catch(IOException e)
			{
				System.out.println(e.toString());
			}
		}
	}
}