s21.htm

提供给JAVA编程者图形界面卷

            <p> textArea.getDocument().addDocumentListener(<br>
              new DocumentListener() {<br>
              public void insertUpdate(DocumentEvent e) {<br>
              saveAction.setEnabled(true);<br>
              updateStatus(e);<br>
              }<br>
              public void removeUpdate(DocumentEvent e) {<br>
              saveAction.setEnabled(true);<br>
              updateStatus(e);<br>
              }<br>
              public void changedUpdate(DocumentEvent e) {<br>
              saveAction.setEnabled(true);<br>
              updateStatus(e);<br>
              }<br>
              private void updateStatus(DocumentEvent e) {<br>
              status.append(e.getType().toString());<br>
              status.append(&quot; Offset: &quot; + e.getOffset());<br>
              status.append(&quot; Length: &quot; + e.getLength() + &quot;\n&quot;);<br>
              }<br>
              });</p>
            <p> setJMenuBar(createMenuBar());<br>
              }<br>
              private JMenuBar createMenuBar() {<br>
              JMenuBar menuBar = new JMenuBar();<br>
              JMenu editMenu = new JMenu(&quot;Edit&quot;);</p>
            <p> editMenu.add(new DefaultEditorKit.CutAction());<br>
              editMenu.add(new DefaultEditorKit.CopyAction());<br>
              editMenu.add(new DefaultEditorKit.PasteAction());<br>
              editMenu.addSeparator();<br>
              editMenu.add(saveAction);</p>
            <p> menuBar.add(editMenu);<br>
              return menuBar;<br>
              }<br>
              public static void main(String args[]) {<br>
              GJApp.launch(new Test(), <br>
              &quot;Using Document Listeners&quot;,<br>
              300,300,650,500);<br>
              }<br>
              }<br>
              class GJApp extends WindowAdapter {<br>
              static private JPanel statusArea = new JPanel();<br>
              static private JLabel status = new JLabel(&quot; &quot;);<br>
              static private ResourceBundle resources;</p>
            <p> public static void launch(final JFrame f, String title,<br>
              final int x, final int y, <br>
              final int w, int h) {<br>
              launch(f,title,x,y,w,h,null); <br>
              }<br>
              public static void launch(final JFrame f, String title,<br>
              final int x, final int y, <br>
              final int w, int h,<br>
              String propertiesFilename) {<br>
              f.setTitle(title);<br>
              f.setBounds(x,y,w,h);<br>
              f.setVisible(true);</p>
            <p> statusArea.setBorder(BorderFactory.createEtchedBorder());<br>
              statusArea.setLayout(new FlowLayout(FlowLayout.LEFT,0,0));<br>
              statusArea.add(status);<br>
              status.setHorizontalAlignment(JLabel.LEFT);</p>
            <p> f.setDefaultCloseOperation(<br>
              WindowConstants.DISPOSE_ON_CLOSE);</p>
            <p> if(propertiesFilename != null) {<br>
              resources = ResourceBundle.getBundle(<br>
              propertiesFilename, Locale.getDefault());<br>
              }</p>
            <p> f.addWindowListener(new WindowAdapter() {<br>
              public void windowClosed(WindowEvent e) {<br>
              System.exit(0);<br>
              }<br>
              });<br>
              }<br>
              static public JPanel getStatusArea() {<br>
              return statusArea;<br>
              }<br>
              static public void showStatus(String s) {<br>
              status.setText(s);<br>
              }<br>
              static Object getResource(String key) {<br>
              if(resources != null) {<br>
              return resources.getString(key);<br>
              }<br>
              return null;<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 21.5 加字符与加重器</p>
            <p>&nbsp;</p>
            <p> 21.5.1 加字符</p>
            <p>&nbsp;</p>
            <p> 21.5.2 加字符监听器</p>
            <p>&nbsp;</p>
            <p align="center"><b>例21-6 实现一个加字符监听器</b></p>
            <hr noshade size="1">
            import java.awt.*;<br>
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import javax.swing.text.*;
            <p>public class Test extends JApplet {<br>
              public Test() {<br>
              Container contentPane = getContentPane();<br>
              JTextArea textArea = new JTextArea();</p>
            <p> contentPane.add(textArea, BorderLayout.CENTER);</p>
            <p> textArea.setFont(new Font(&quot;Dialog&quot;, Font.PLAIN, 24));</p>
            <p> textArea.addCaretListener(new CaretListener() {<br>
              public void caretUpdate(CaretEvent e) {<br>
              showStatus(&quot;Mark: &quot; + e.getMark() +<br>
              &quot; / Dot: &quot; + e.getDot());<br>
              }<br>
              });<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 21.5.3 定制加字符</p>
            <p>&nbsp;</p>
            <p align="center"><b>例21-7 实现一个定制加字符</b></p>
            <hr noshade size="1">
            import javax.swing.*;<br>
            import javax.swing.plaf.*;<br>
            import javax.swing.text.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import java.util.*;
            <p>public class Test extends JApplet {<br>
              public Test() {<br>
              Container contentPane = getContentPane();<br>
              JTextArea textArea = new JTextArea();</p>
            <p> textArea.setCaret(new TriangleCaret(8));<br>
              textArea.setFont(new Font(&quot;Dialog&quot;, Font.ITALIC, 24));<br>
              contentPane.add(textArea, BorderLayout.CENTER);<br>
              }<br>
              }<br>
              class TriangleCaret extends DefaultCaret {<br>
              private int triangleWidth, left, right, top, bottom, middle;</p>
            <p> public TriangleCaret(int triangleWidth) {<br>
              this.triangleWidth = triangleWidth;<br>
              }<br>
              public void paint(Graphics g) {<br>
              if(isVisible()) {<br>
              try {<br>
              JTextComponent comp = getComponent();<br>
              Rectangle r = comp.modelToView(getDot());</p>
            <p> setLocations(r);<br>
              g.setColor(comp.getCaretColor());</p>
            <p> g.drawLine(left, bottom, middle, top);<br>
              g.drawLine(middle, top, right, bottom);<br>
              g.drawLine(right, bottom, left, bottom);<br>
              }<br>
              catch(BadLocationException ex) {<br>
              ex.printStackTrace();<br>
              }<br>
              }<br>
              }<br>
              protected synchronized void damage(Rectangle r) {<br>
              if(r != null) {<br>
              setLocations(r);<br>
              x = left;<br>
              y = top;<br>
              width = right - left + 1;<br>
              height = bottom - top + 1;<br>
              }<br>
              }<br>
              private void setLocations(Rectangle r) {<br>
              left = r.x - triangleWidth/2; <br>
              right = r.x + triangleWidth/2;<br>
              bottom = r.y + r.height - 1; <br>
              top = bottom - triangleWidth;<br>
              middle = r.x;</p>
            <p> repaint();<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 21.5.4 加重器</p>
            <p>&nbsp;</p>
            <p align="center"><b>例21-8 一个定制的加重器</b></p>
            <hr noshade size="1">
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import javax.swing.*;<br>
            import javax.swing.text.*;
            <p>public class Test extends JApplet {<br>
              public Test() {<br>
              Container contentPane = getContentPane();<br>
              JTextArea textArea = new JTextArea(<br>
              &quot;File choosers, like option panes, are lightweight\n&quot; 
              +<br>
              &quot;components that\n&quot; +<br>
              &quot;are meant to be placed ...&quot;);</p>
            <p> textArea.setCaret(new BoxHighlightingCaret());<br>
              textArea.setFont(new Font(&quot;Dialog&quot;, Font.ITALIC, 24));</p>
            <p> contentPane.add(new JScrollPane(textArea), <br>
              BorderLayout.CENTER);<br>
              }<br>
              }<br>
              class BoxHighlightingCaret extends DefaultCaret {<br>
              private static BoxHighlighterPainter painter = <br>
              new BoxHighlighterPainter(null);</p>
            <p> public Highlighter.HighlightPainter getSelectionPainter(){<br>
              return painter;<br>
              }<br>
              static class BoxHighlighterPainter <br>
              extends DefaultHighlighter.DefaultHighlightPainter {<br>
              private Color color;</p>
            <p> public BoxHighlighterPainter(Color color) {<br>
              super(color);<br>
              this.color = color;<br>
              }<br>
              public Shape paintLayer(Graphics g, int p0, int p1, <br>
              Shape shape, JTextComponent comp,<br>
              View view) {<br>
              Rectangle b = shape.getBounds();</p>
            <p> try {<br>
              g.setColor(getColor(comp));</p>
            <p> Rectangle r1 = comp.modelToView(p0);<br>
              Rectangle r2 = comp.modelToView(p1);</p>
            <p> g.drawRect(r1.x, r1.y, // x,y<br>
              r2.x - r1.x - 1, // width<br>
              r1.height - 1); // height<br>
              }<br>
              catch(BadLocationException ex) {<br>
              ex.printStackTrace();<br>
              }<br>
              return b;<br>
              }<br>
              private Color getColor(JTextComponent comp) {<br>
              return color != null ? color : <br>
              comp.getSelectionColor();<br>
              }<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 21.6 撤销/恢复</p>
            <p>&nbsp;</p>
            <p align="center"><b>例21-9 一个撤消和恢复的实现</b></p>
            <hr noshade size="1">
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import javax.swing.*;<br>
            import javax.swing.event.*;<br>
            import javax.swing.text.*;<br>
            import javax.swing.undo.*;
            <p>public class Test extends JApplet {<br>
              private JTextArea textArea = new JTextArea(&quot;some content&quot;);<br>
              private Document document = textArea.getDocument();<br>
              private UndoManager undoManager = new UndoManager();<br>
              private UndoLastAction undoAction = new UndoLastAction();<br>
              private RedoAction redoAction = new RedoAction();</p>
            <p> public Test() {<br>
              Container contentPane = getContentPane();</p>
            <p> createMenu();<br>
              contentPane.add(textArea, BorderLayout.CENTER);</p>
            <p> textArea.setFont(new Font(&quot;Dialog&quot;, Font.PLAIN, 24));<br>
              document.addUndoableEditListener(<br>
              new UndoableEditListener() {<br>
              public void undoableEditHappened(UndoableEditEvent e){<br>
              undoManager.addEdit(e.getEdit());<br>
              undoAction.update();<br>
              redoAction.update();<br>
              }<br>
              });<br>
              }<br>
              private void createMenu() {<br>
              JMenuBar menuBar = new JMenuBar();<br>
              JMenu editMenu = new JMenu(&quot;Edit&quot;);</p>
            <p> editMenu.add(new DefaultEditorKit.CutAction());<br>
              editMenu.add(new DefaultEditorKit.CopyAction());<br>
              editMenu.add(new DefaultEditorKit.PasteAction());</p>
            <p> editMenu.addSeparator();</p>
            <p> editMenu.add(undoAction);<br>
              editMenu.add(redoAction);</p>
            <p> menuBar.add(editMenu);<br>
              setJMenuBar(menuBar);<br>
              }<br>
              class RedoAction extends AbstractAction {<br>
              public RedoAction() {<br>
              super(&quot;Redo&quot;);<br>
              update();<br>
              }<br>
              public void actionPerformed(ActionEvent e) {<br>
              undoManager.redo();<br>
              undoAction.update();<br>
              update();<br>
              }<br>
              public void update() {<br>
              boolean canRedo = undoManager.canRedo();</p>
            <p> if(canRedo) {<br>
              setEnabled(true);<br>
              putValue(Action.NAME, <br>
              undoManager.getRedoPresentationName());<br>
              }<br>
              else {<br>
              setEnabled(false);<br>
              putValue(Action.NAME, &quot;Redo&quot;);<br>
              }<br>
              }<br>
              }<br>
              class UndoLastAction extends AbstractAction {<br>
              public UndoLastAction() {<br>
              super(&quot;Undo&quot;);<br>
              update();<br>
              }<br>
              public void actionPerformed(ActionEvent e) {<br>
              undoManager.undo();<br>
              redoAction.update();<br>
              update();<br>
              }<br>
              public void update() {<br>
              boolean canUndo = undoManager.canUndo();</p>
            <p> if(canUndo) {<br>
              setEnabled(true);<br>
              putValue(Action.NAME, <br>
              undoManager.getUndoPresentationName());<br>
              }<br>
              else {<br>
              setEnabled(false);<br>
              putValue(Action.NAME, &quot;Undo&quot;);<br>
              }<br>
              }<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 21.7 JTextComponent</p>
            <p>&nbsp;</p>
            <p> 21.8 本章回顾</p>
            <p>&nbsp;</p>
            <p>[<a href="index.html" target="_self">目录</a>][<a href="s20.htm">上一页</a>][<a href="s22.htm">下一页</a>](飒龙收藏/2002.5.18) 
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