Java核心代码（六） 桌面程序--记事本

参考文档http://wenku.baidu.com/view/45450b0f79563c1ec4da7101.html

1、命令：

D:\desktop>javac -d ./ JNotePad.java

D:\desktop>jar cvf jnotepad.jar desktop

added manifest

adding: desktop/(in = 0) (out= 0)(stored 0%)

adding: desktop/11/(in = 0) (out= 0)(stored 0%)

adding: desktop/JNotePad$1.class(in = 520) (out= 342)(deflated 34%)

打开jnotepad.jar\META-INF\MAINIFEST.MF添加：

Main-Class: desktop.JNotePad

2、记事本代码：

package desktop;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.ScrollPaneConstants;

/**
 * @author timeriver.wang
 * @date 2013-01-04 6:23:45 PM
 */
public class JNotePad extends JFrame {
    private JMenu fileMenu;//should be filed or local variables?
    private JMenuItem openMenuItem;
    private JMenuItem saveMenuItem;
    private JMenuItem saveAsMenuItem;
    private JMenuItem closeMenuItem;
    private JMenuItem aboutMenuItem;
    private JTextArea textArea;
    private JFileChooser fileChooser;
    private boolean isChanged = false;

    public JNotePad() {
        super( "new txt file" );
        setUI();
        setEventListener();
        setVisible( true );
    }

    public static void main( String[] args ) {
        new JNotePad();
    }
    
    private void setUI() {
        setSize( 640, 480 );
        JMenuBar menuBar = new JMenuBar();
        //-------------------------------//
        //file Menu
        //-------------------------------//
        fileMenu = new JMenu( "file" );
        openMenuItem = new JMenuItem( "open" );
        // shortcut key,VK_O-->'O',CTRL_MASK-->"ctrl"
        openMenuItem.setAccelerator( KeyStroke.getKeyStroke( KeyEvent.VK_O, InputEvent.CTRL_MASK ) );
        saveMenuItem = new JMenuItem( "save" );
        saveMenuItem.setAccelerator( KeyStroke.getKeyStroke( KeyEvent.VK_S, InputEvent.CTRL_MASK ) );
        saveAsMenuItem = new JMenuItem( "save as" );
        closeMenuItem = new JMenuItem( "close" );
        closeMenuItem.setAccelerator( KeyStroke.getKeyStroke( KeyEvent.VK_Q, InputEvent.CTRL_MASK ) );
        fileMenu.add( openMenuItem );
        fileMenu.addSeparator(); 
        fileMenu.add( saveMenuItem );
        fileMenu.addSeparator();
        fileMenu.add( saveAsMenuItem );
        fileMenu.addSeparator(); 
        fileMenu.add( closeMenuItem );
        //-------------------------------//
        //help Menu
        //-------------------------------//
        JMenu helpMenu = new JMenu( "help" );
        aboutMenuItem = new JMenuItem( "about" );
        helpMenu.add( aboutMenuItem );
        //
        menuBar.add( fileMenu );
        menuBar.add( helpMenu );
        //
        setJMenuBar( menuBar );

        // textArea
        textArea = new JTextArea();
        textArea.setLineWrap( true );
        JScrollPane panel = new JScrollPane( textArea, 
            ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
            ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED );
        Container contentPane = getContentPane();
        contentPane.add( panel, BorderLayout.CENTER );
        // 
        fileChooser = new JFileChooser();
    }

    private void setEventListener() {
        addWindowListener( new WindowAdapter() {
            public void windowClosing( WindowEvent e ) {
                closeFile();
            }
        } );

        openMenuItem.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
                openFile();
            }
        } );

        saveMenuItem.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
                saveFile();
            }
        } );

        saveAsMenuItem.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
                saveFileAs();
            }
        } );

        closeMenuItem.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
                closeFile();
            }
        } );

        aboutMenuItem.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent e ) {
                JOptionPane.showOptionDialog( null, 
                    "java desktop demo,jar,started by bat command", "about JNotePad",
                    JOptionPane.DEFAULT_OPTION, JOptionPane.INFORMATION_MESSAGE, null, null,
                    null );
            }
        } );

        // key event
        textArea.addKeyListener( new KeyAdapter() {
            public void keyTyped( KeyEvent e ) {
            }
        } );

        // mouse event
        textArea.addMouseListener( new MouseAdapter() {
            public void mouseReleased( MouseEvent e ) {
            }
            public void mouseClicked( MouseEvent e ) {
            }
        } );
    }

    private void openFile() {
        if ( !isChanged ) {
            open();
        }else {
            int option = JOptionPane.showConfirmDialog( null, 
                "file is changed, do you want to save?", "save file?", JOptionPane.YES_NO_OPTION,
                JOptionPane.WARNING_MESSAGE, null );
            if(option == JOptionPane.YES_OPTION){
                saveFile(); 
            }else{
                open();
            }
        }
    }
    private void open() {
        int option = fileChooser.showDialog( null, null );
        if ( option == JFileChooser.APPROVE_OPTION ) {
            try {
                BufferedReader buf = new BufferedReader( new FileReader( fileChooser.getSelectedFile() ) );
                setTitle( fileChooser.getSelectedFile().toString() );
                textArea.setText( "" );
                isChanged = true;
                String lineSeparator = System.getProperty( "line.separator" );
                String text;
                while ( ( text = buf.readLine() ) != null ) {
                    textArea.append( text );
                    textArea.append( lineSeparator );
                }
                buf.close();
            }
            catch ( IOException e ) {
                JOptionPane.showMessageDialog( null, e.toString(), 
                    "open file fail!", JOptionPane.ERROR_MESSAGE );
            }
        }
    }

    private void saveFile() {
        File file = new File( getTitle() );
        if ( !file.exists() ) {
            saveFileAs();
        }else {
            try {
                BufferedWriter buf = new BufferedWriter( new FileWriter( file ) );
                buf.write( textArea.getText() );
                buf.close();
                isChanged = false;
            }
            catch ( IOException e ) {
                JOptionPane.showMessageDialog( null, e.toString(), 
                    "write file fail!", JOptionPane.ERROR_MESSAGE );
            }
        }
    }

    private void saveFileAs() {
        int option = fileChooser.showSaveDialog( null );
        if ( option == JFileChooser.APPROVE_OPTION ) {
            File file = fileChooser.getSelectedFile();
            setTitle( file.toString() );
            try {
                file.createNewFile();
                saveFile();
            }
            catch ( IOException e ) {
                JOptionPane.showMessageDialog( null, e.toString(), 
                    "save as file fail!", JOptionPane.ERROR_MESSAGE );
            }
        }
    }

    private void closeFile() {
        if ( isChanged ) {
            dispose();
        }else {
            int option = JOptionPane.showConfirmDialog( null, 
                "file has changed,save?", "save file?", JOptionPane.YES_NO_OPTION,
                JOptionPane.WARNING_MESSAGE, null );
            if(option == JOptionPane.YES_OPTION){
                saveFile();
            }else{
                dispose();
            }
        }
    }
}