Java Swing实现的简单记事本

package com.test.demo;

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

import javax.swing.*;

class MyNotePad extends JFrame implements ActionListener {

	private JTextArea jta = null;
	private JMenuBar jmb = null;
	private JMenu jm = null;
	private JMenuItem jmiOpen = null;
	private JMenuItem jmiSave = null;
	private JMenuItem jmiExit = null;

	private JFileChooser jfc = null;

	public MyNotePad() {
		jta = new JTextArea();
		this.setLayout(new BorderLayout());
		this.add(jta);

		jmb = new JMenuBar();
		jm = new JMenu("File");
		jmiOpen = new JMenuItem("open");
		jmiOpen.addActionListener(this);
		jmiOpen.setActionCommand("open");

		jmiSave = new JMenuItem("save");
		jmiSave.addActionListener(this);
		jmiSave.setActionCommand("save");

		jmiExit = new JMenuItem("exit");
		jmiExit.addActionListener(this);
		jmiExit.setActionCommand("exit");

		jm.add(jmiOpen);

		jm.add(jmiSave);
		jm.add(jmiExit);
		jmb.add(jm);
		this.setJMenuBar(jmb);

		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setSize(400, 300);
		this.setVisible(true);

	}

	@Override
	public void actionPerformed(ActionEvent e) {
		// TODO Auto-generated method stub
		String str = e.getActionCommand();
		if (str.equals("open")) {
			System.out.println("open");
			jfc = new JFileChooser();
			jfc.setDialogTitle("please select file");
			jfc.showOpenDialog(null);
			jfc.setVisible(true);

			File file = jfc.getSelectedFile();
			BufferedReader br = null;

			try {
				FileReader fReader = new FileReader(file);
				br = new BufferedReader(fReader);
				String readStr = "";
				String allCode = "";
				while ((readStr = br.readLine()) != null) {
					allCode += readStr + "\r\n";
				}
				jta.setText(allCode);

			} catch (Exception e2) {
				e2.printStackTrace();
				// TODO: handle exception
			} finally {
				try {
					br.close();
				} catch (IOException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}
			}

		} else if (str.equals("save")) {
			JFileChooser jfc = new JFileChooser();
			jfc.setDialogTitle("save as");
			jfc.showSaveDialog(null);
			File file = jfc.getSelectedFile();
			BufferedWriter bw = null;

			try {
				FileWriter fw = new FileWriter(file);
				bw = new BufferedWriter(fw);
				String jtaStr = jta.getText();
				bw.write(jtaStr);
			} catch (Exception e2) {
				// TODO: handle exception
				e2.printStackTrace();
			} finally {
				try {
					bw.close();
				} catch (IOException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}
			}

		} else if (str.equals("exit")) {
			System.exit(0);
		}
	}
}

public class TestMain {

	public static void main(String[] str) {
		MyNotePad notePad = new MyNotePad();
	}

}