制作一个Frame用于保存文件和打开文件

import java.awt.BorderLayout;


public class FrameMenu extends JFrame {

	private static final String LINE_SEPARATOR = System.getProperty("line.separator");
	/**
	 * Launch the application.
	 */
	private JFileChooser chooser;
	private JTextArea textArea;
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					FrameMenu frame = new FrameMenu();
					frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the frame.
	 */
	public FrameMenu() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 612, 447);
		getContentPane().setLayout(null);
		getContentPane().setLayout(new BorderLayout(0, 0));
		
		JScrollPane scrollPane = new JScrollPane();
		scrollPane.setBounds(131, 69, 2, 2);
		getContentPane().add(scrollPane);
		
		textArea = new JTextArea();
		scrollPane.setViewportView(textArea);
		
		JMenuBar menuBar = new JMenuBar();
		setJMenuBar(menuBar);
		
		JMenu mnNewMenu = new JMenu("文件");
		menuBar.add(mnNewMenu);
		
		JMenuItem mntmNewMenuItem = new JMenuItem("打开");
		mntmNewMenuItem.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				try {
					showdig();
				} catch (IOException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}
			}
		});
		mnNewMenu.add(mntmNewMenuItem);
		
		JMenuItem mntmNewMenuItem_1 = new JMenuItem("保存");
		mntmNewMenuItem_1.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				try {
					savedig();
				} catch (IOException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				}
			}
		});
		mnNewMenu.add(mntmNewMenuItem_1);
	}

	public void showdig() throws IOException {
		chooser = new JFileChooser();
		int boo = chooser.showOpenDialog(this);
		if(boo == JFileChooser.CANCEL_OPTION)
		{
			System.out.println("哥们你没有选择文件");
			return ;
		}
		File file = chooser.getSelectedFile();
		@SuppressWarnings("resource")
		BufferedReader bfr = new BufferedReader(new FileReader(file));
		
		textArea.setText("");;
		String line = null;
		while((line = bfr.readLine()) != null)
		{
			textArea.append(line + LINE_SEPARATOR);
		}
		
	}

	public void savedig() throws IOException {
		chooser = new JFileChooser();
		int chr = chooser.showSaveDialog(this);
		if(chr == JFileChooser.CANCEL_OPTION)
		{
			System.out.println("没有指定文件");
			return ;
		}
		File file = chooser.getSelectedFile();
		
		BufferedWriter bfw = new BufferedWriter(new FileWriter(file));
		String str = textArea.getText();
		bfw.write(str);
		bfw.close();
	}
}