由Java实现简单的文本编辑器

申明：以下代码由Qdieyou原创，任何转载请注明出处，否则追究责任，谢谢！

文章首发：http://bbs.cfanhome.com/dispbbs.asp?boardid=40&rootid=&id=525651

经过测试，本代码适合JDK 1.5.0其他版本的JDK可能存在函数的不兼容。

由于本人所学的教材是英文版的“How to java program”所以，以下代码部分注释也采用英文形式，相信大家是看得懂的。代码的注释已经写得很清楚，这里就不多做解释了。

代码如下：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Notepad extends JFrame{
private final Color colorvalues[] =
{ Color.black, Color.blue, Color.red, Color.green }; //定义颜色数组
String styleNames[] = { "Bold", "Italic" };//定义风格数组
String fontNames[] = { "宋体", "华文行楷", "隶书" };//字体数组
String[] sizeString = new String[30];//字号数组
int[] size = new int[30];//与字号数组对应的字号整数，用于设置文字大小
private JRadioButtonMenuItem colorItems[], fonts[];
private JCheckBoxMenuItem styleItems[];
private JTextArea displayText;//定义文本编辑区
private ButtonGroup fontGroup, colorGroup;//字体组，跟字色组
private int style;//字体风格
private JScrollPane scroll;//为文本编辑区提供滚动条
private String selectText = "";//存放文本编辑区中选中的文本内容
private JComboBox styleBox,fontBox,sizeBox;//工具栏
private JPanel toolPanel;//存放工具栏
private int rowNumber = 0;

// set up GUI
public Notepad()
{
super( "记事本" );//标题

//初始化字体大小数组
for(int i = 0 ; i<size.length;i++){
sizeString[i] = "" + (i+5) * 2;
size[i] = (i+5)*2;
}

Container container = getContentPane();
container.setLayout(new BorderLayout() );

//统计行数

toolPanel = new JPanel();

JLabel label1 = new JLabel("字体名称");
toolPanel.add(label1);
fontBox = new JComboBox(fontNames);
fontBox.addItemListener( //事件处理
new ItemListener(){

public void itemStateChanged(ItemEvent event){
if( event.getStateChange() == ItemEvent.SELECTED){
displayText.setFont( new Font( fontNames[fontBox.getSelectedIndex()],
displayText.getFont().getStyle(), displayText.getFont().getSize() ) );

}
}
}
);
toolPanel.add(fontBox);//添加

JLabel label2 = new JLabel("字体风格");
toolPanel.add(label2);
String style_name[] = {"常规","倾斜","粗体","倾斜加粗体"};//字体风格
styleBox = new JComboBox(style_name);
styleBox.addItemListener( //事件处理
new ItemListener(){

public void itemStateChanged(ItemEvent event){
if( event.getStateChange() == ItemEvent.SELECTED){
if(styleBox.getSelectedIndex()==0) style = Font.PLAIN;
if(styleBox.getSelectedIndex()==1) style = Font.ITALIC;
if(styleBox.getSelectedIndex()==2) style = Font.BOLD;
if(styleBox.getSelectedIndex()==3) style = Font.ITALIC+Font.BOLD;
displayText.setFont( new Font( displayText.getFont().getName(),
style, displayText.getFont().getSize() ) );

}
}
}
);

toolPanel.add( styleBox );

JLabel label3 = new JLabel("字号");
toolPanel.add(label3);
sizeBox = new JComboBox(sizeString);
sizeBox.addItemListener(
new ItemListener(){

public void itemStateChanged(ItemEvent event){
if( event.getStateChange() == ItemEvent.SELECTED){
displayText.setFont( new Font( displayText.getFont().getName(),
displayText.getFont().getStyle(), size[sizeBox.getSelectedIndex()] ) );

}
}
}
);
toolPanel.add(sizeBox);
container.add( toolPanel, BorderLayout.NORTH );

// set up File menu and its menu items
JMenu fileMenu = new JMenu( "文件(F)" );
fileMenu.setMnemonic( 'F' );

// set up About... menu item
JMenuItem aboutItem = new JMenuItem( "关于(A)..." );
aboutItem.setMnemonic( 'A' );
fileMenu.add( aboutItem );
aboutItem.addActionListener(

new ActionListener() { // anonymous inner class

// display message dialog when user selects About...
public void actionPerformed( ActionEvent event )
{
JOptionPane.showMessageDialog( Notepad.this,
"模拟记事本程序/ncopyright@2005_Qdieyou——魏逢一",
"关于", JOptionPane.PLAIN_MESSAGE );
rowNumber = displayText.getRows();
JOptionPane.showMessageDialog(null,""+ rowNumber);
}

} // end anonymous inner class

); // end call to addActionListener

// set up Exit menu item退出菜单
JMenuItem exitItem = new JMenuItem( "Exit" );
exitItem.setMnemonic( 'x' );
fileMenu.add( exitItem );
exitItem.addActionListener(

new ActionListener() { // anonymous inner class

// terminate application when user clicks exitItem
public void actionPerformed( ActionEvent event )
{
System.exit( 0 );
}

} // end anonymous inner class

); // end call to addActionListener

// create menu bar and attach it to MenuTest window
JMenuBar bar = new JMenuBar();
setJMenuBar( bar );
bar.add( fileMenu );

JMenu editMenu = new JMenu( "编辑(E)" );
editMenu.setMnemonic( 'E' );

//复制菜单选项
JMenuItem copyItem = new JMenuItem( "复制(C)" );
copyItem.setMnemonic( 'C' );
editMenu.add( copyItem );
copyItem.addActionListener(
new ActionListener(){
public void actionPerformed( ActionEvent event ){
selectText = displayText.getSelectedText();//获得选中的内容，并保存在selectText里
}
}
);

//粘贴的实现
JMenuItem pasteItem = new JMenuItem( "粘贴(P)" );
pasteItem.setMnemonic( 'P' );
editMenu.add( pasteItem );
pasteItem.addActionListener(
new ActionListener(){
public void actionPerformed( ActionEvent event ){
int position = displayText.getCaretPosition();//获得鼠标当前位置
displayText.insert( selectText,position );//插入到鼠标当前位置
}
}
);

JMenuItem swapItem = new JMenuItem( "替换(R)..." );
swapItem.setMnemonic( 'R' );
editMenu.add( swapItem );
swapItem.addActionListener(
new ActionListener(){
public void actionPerformed( ActionEvent event ){
JPanel swapPanel = new JPanel();
JLabel lookupLabel = new JLabel("要替换的内容");
JTextField inputText = new JTextField(10);
JLabel swapLabel = new JLabel("替换为：");
JTextField changetoText = new JTextField(10);
swapPanel.add( lookupLabel );
swapPanel.add( inputText );
swapPanel.add( swapLabel );
swapPanel.add( changetoText );
JOptionPane.showMessageDialog(null,swapPanel);
String text = displayText.getText();//获得整个文本内容
String changeText = text.replace(inputText.getText(),changetoText.getText());//获得替换后的内容
displayText.setText(changeText);

}
}
);

bar.add( editMenu );//add editMenu

// create Format menu, its submenus and menu items
JMenu formatMenu = new JMenu( "格式(R)" );
formatMenu.setMnemonic( 'R' );

//自动换行的功能切换
JMenuItem changeItem = new JMenuItem( "自动换行(W)" );
changeItem.setMnemonic( 'W' );
formatMenu.add( changeItem );
changeItem.addActionListener(
new ActionListener(){
boolean var = false;
public void actionPerformed( ActionEvent event ){

if(var) var = false;
else var=true;
displayText.setLineWrap(var);
}
}
);

// create Color submenu
String colors[] = { "Black", "Blue", "Red", "Green" };

JMenu colorMenu = new JMenu( "Color" );
colorMenu.setMnemonic( 'C' );

colorItems = new JRadioButtonMenuItem[ colors.length ];
colorGroup = new ButtonGroup();
ItemHandler itemHandler = new ItemHandler();

// create color radio button menu items
for ( int count = 0; count < colors.length; count++ ) {
colorItems[ count ] =
new JRadioButtonMenuItem( colors[ count ] );
colorMenu.add( colorItems[ count ] );
colorGroup.add( colorItems[ count ] );
colorItems[ count ].addActionListener( itemHandler );
}

// select first Color menu item
colorItems[ 0 ].setSelected( true );

// add format menu to menu bar
formatMenu.add( colorMenu );
formatMenu.addSeparator();

// create Font submenu
JMenu fontMenu = new JMenu( "Font" );
fontMenu.setMnemonic( 'n' );

fonts = new JRadioButtonMenuItem[ fontNames.length ];
fontGroup = new ButtonGroup();

// create Font radio button menu items
for ( int count = 0; count < fonts.length; count++ ) {
fonts[ count ] = new JRadioButtonMenuItem( fontNames[ count ] );
fontMenu.add( fonts[ count ] );
fontGroup.add( fonts[ count ] );
fonts[ count ].addActionListener( itemHandler );
}

// select first Font menu item
fonts[ 0 ].setSelected( true );

fontMenu.addSeparator();

// set up style menu items

styleItems = new JCheckBoxMenuItem[ styleNames.length ];

// create style checkbox menu items
for ( int count = 0; count < styleNames.length; count++ ) {
styleItems[ count ] =
new JCheckBoxMenuItem( styleNames[ count ] );
fontMenu.add( styleItems[ count ] );
StyleHandler styleHandler = new StyleHandler();
styleItems[ count ].addItemListener( styleHandler );
}

// put Font menu in Format menu
formatMenu.add( fontMenu );

// add Format menu to menu bar
bar.add( formatMenu );

JMenu helpMenu = new JMenu( "帮助(H)" );
helpMenu.setMnemonic( 'H' );

//帮助菜单项
JMenuItem helpItem = new JMenuItem( "帮助主题(H)..." );
helpItem.setMnemonic( 'H' );
helpMenu.add( helpItem );
helpItem.addActionListener(
new ActionListener(){
public void actionPerformed( ActionEvent event ){
JTextArea helpText = new JTextArea(
"格式里的自动换行说明：单击一次切换功能/n只能实现整个文本的风格，字体等的设置/n"+
"复制，粘贴可以实现插入到鼠标当前位置/n标题栏显示行数");
JScrollPane scroller = new JScrollPane(helpText);
JOptionPane.showMessageDialog(null,scroller);
}
}
);
bar.add( helpMenu ); //添加

// set up label to display text
displayText = new JTextArea();
displayText.setForeground( colorvalues[ 0 ] );
displayText.setFont( new Font( "Serif", Font.PLAIN, 24 ) );//设置默认字体
scroll = new JScrollPane( displayText,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS );

container.add( scroll, BorderLayout.CENTER );
displayText.addKeyListener( //通过对displayText注册键盘事件来获得当前文本的 行数
new KeyListener(){
public void keyPressed( KeyEvent event ){
rowNumber = displayText.getLineCount();//获得文本区的函数
setTitle("总共" + rowNumber + "行");//设置标题
}

public void keyReleased( KeyEvent event ){//空
}
public void keyTyped( KeyEvent event ){//空
}
}
);

setSize( 700, 500 );
setVisible( true );

} // end constructor

public static void main( String args[] )
{
Notepad application = new Notepad();
application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
}

// inner class to handle action events from menu items
private class ItemHandler implements ActionListener {

// process color and font selections
public void actionPerformed( ActionEvent event )
{
// process color selection
for ( int count = 0; count < colorItems.length; count++ )

if ( colorItems[ count ].isSelected() ) {
displayText.setForeground( colorvalues[ count ] );
break;
}

// process font selection
for ( int count = 0; count < fonts.length; count++ )

if ( event.getSource() == fonts[ count ] ) {
displayText.setFont(
new Font( fonts[ count ].getText(), style, 72 ) );
break;
}

repaint();

} // end method actionPerformed

} // end class ItemHandler

// inner class to handle item events from check box menu items
private class StyleHandler implements ItemListener {

// process font style selections
public void itemStateChanged( ItemEvent e )
{
style = 0;

// check for bold selection
if ( styleItems[ 0 ].isSelected() )
style += Font.BOLD;

// check for italic selection
if ( styleItems[ 1 ].isSelected() )
style += Font.ITALIC;

displayText.setFont(
new Font( displayText.getFont().getName(), style, 72 ) );

repaint();
}

} // end class StyleHandler

} // end class Notepad