filebrowser.java

程序练习中包括书中实例程序代码和练习中要用到的代码,是压缩文件

package examples.windows;
import java.awt.*;
import java.awt.event.*;
import java.io.*;

/** An example class used to demonstrate the
  * use of menus, menu items, dialog boxes,
  * etc. using AWT components
  */
public class FileBrowser extends Frame {

   private FontDialog fontDialog;
   private TextField  statusLine;
   private TextArea   text;

   /** Class constructor
     * @param titleText Title bar text
     */
   public FileBrowser( String titleText ) {
      super( titleText );
      addWindowListener( new WindowCloser() );
      setLayout( new BorderLayout() );

      setMenuBar( buildMenuBar() );
      text = new TextArea();
      text.setEditable( false );
      text.setBackground( Color.white );
      add( text, BorderLayout.CENTER );

      statusLine = new TextField();
      add( statusLine, BorderLayout.SOUTH );

      setSize( 500, 400 );
      setVisible( true );
   }

   /** Present a dialog box to have the user select
     * the file for browsing */
   public void loadFile() {
      FileDialog fileDialog
         = new FileDialog( this, "File Open",
                           FileDialog.LOAD );
      fileDialog.setVisible( true );
      if ( fileDialog.getFile() != null ) try {      
         FileReader fr = new FileReader( 
               fileDialog.getDirectory() +
               fileDialog.getFile() );
         text.setText( "" );
         text.setVisible( false );
         char[] charBuffer = new char[4096];
         int charsRead = fr.read( charBuffer, 0,
                                  charBuffer.length );
         while ( charsRead != -1 ) {
            text.append( new String( charBuffer, 0,
                                     charsRead ) );
            charsRead = fr.read( charBuffer, 0,
                                 charBuffer.length );
         }
         text.setVisible( true );
      } catch( IOException ioe ) {
         statusLine.setText( ioe.toString() );
      }
      fileDialog.dispose();
   }

   /** Build the menu bar, menus, and menu items for
     * the file browser */
   public MenuBar buildMenuBar() {
      MenuBar menuBar = new MenuBar();
      Menu fileMenu = new Menu( "File" );
      Menu editMenu = new Menu( "Edit" );
      MenuItem exitItem = new MenuItem( "Exit" );
      MenuItem fileOpenItem
         = new MenuItem( "File open..." );
      MenuItem fontsItem
         = new MenuItem( "Fonts..." );

      fileOpenItem.setShortcut(
         new MenuShortcut( KeyEvent.VK_O ) );
      fontsItem.setShortcut(
         new MenuShortcut( KeyEvent.VK_F ) );      

      fileOpenItem.addActionListener(
         new ActionListener() {
            public void
            actionPerformed( ActionEvent event ) {
               loadFile();
            }
         }
      );

      exitItem.addActionListener(
         new ActionListener() {
            public void
            actionPerformed( ActionEvent event ) {
               dispose();
               System.exit( 0 );
            }
         }
      );

      fontsItem.addActionListener(
         new ActionListener() {
            public void
            actionPerformed( ActionEvent event ) {
               updateFont();
            }
         }
      );

      menuBar.add( fileMenu );
      menuBar.add( editMenu );
      fileMenu.add( fileOpenItem );
      fileMenu.add( exitItem );
      editMenu.add( fontsItem );

      return menuBar;
   }

   /** Allow font selection and update */
   public void updateFont() {
      if ( fontDialog == null ) {
         fontDialog
            = new FontDialog( this, text.getFont() );
      } else {
         fontDialog.setFont( text.getFont() );
         fontDialog.setVisible( true );
      }
      Font f = text.getFont();
      String chosenFont = fontDialog.getFontName();
      if ( chosenFont != null ) {
         text.setFont( new Font( chosenFont,
                                 f.getStyle(),
                                 f.getSize() ) );
      }
   }

   /** The test method for the class
     * @param args not used
     */
   public static void main( String[] args ) {
      new FileBrowser( "File Browser Sample" );
   }
}

class FontDialog extends Dialog {

   private List fontChoices;
   private String fontName;
   private GraphicsEnvironment ge;
   private String[] availableFonts;
   private static final int VISIBLE_CHOICES = 12;

   /** Class constructor
     * @param parent The dialog box's parent window
     *    (the main browser window)
     * @param currentFont Font being used in
     *    the main browser window
     */
   public FontDialog( Frame parent, Font initialFont ){
      super( parent, "Fonts", true );
      addWindowListener( new WindowAdapter() {
            /* Disappear when the window is closed */
            public void
            windowClosing( WindowEvent e ) {
               e.getWindow().setVisible( false );
            }
         }
      );
      setLayout( new BorderLayout() );

      final Button okay = new Button( "Apply" );
      okay.setEnabled( false );
      okay.addActionListener(
         new ActionListener() {
            public void
            actionPerformed( ActionEvent event ) {
               fontName
                  = fontChoices.getSelectedItem();
               setVisible( false );
            }
         }
      );

      final Button cancel = new Button( "Cancel" );
      cancel.addActionListener(
         new ActionListener() {
            public void
            actionPerformed( ActionEvent event ) {
               fontName = null;
               dispose();
            }
         }
      );

      if ( ge == null ) {
         ge = ge.getLocalGraphicsEnvironment();
      }
      if ( availableFonts == null ) {
         availableFonts
            = ge.getAvailableFontFamilyNames();
      }
      fontChoices = new List( VISIBLE_CHOICES, false );
      for ( int i=0; i<availableFonts.length; i++ ) {
         fontChoices.add( availableFonts[i] );
         if ( availableFonts[i].equals( 
                           initialFont.getName() ) ) {
            fontChoices.select( i );
         }
      }
      fontChoices.addItemListener( 
         new ItemListener() {
            public void itemStateChanged( 
                       ItemEvent event ) {
               if ( event.getStateChange() ==
                       ItemEvent.SELECTED ) {
                  fontName = 
                       fontChoices.getSelectedItem();
                  okay.setEnabled( true );
               }
            }
         }
      );
      add( new Label( "Font name choices:" ),
                      BorderLayout.NORTH );
      add( fontChoices, BorderLayout.CENTER );

      Panel buttonPanel = new Panel();
      buttonPanel.add( okay );
      buttonPanel.add( cancel );
      add( buttonPanel, BorderLayout.SOUTH );

      Insets i = getParent().getInsets();
      setLocation( i.left, i.top );
      pack();
      setVisible( true );
   }

   /** Retrieve the font name selected by the user
     * @return The name of the font selected
     */
   public String getFontName() {
      return fontName;
   }

   /** Set the initial font name selected by the user
     * @param initialFont the name of the
     *        initial font selected
     */
   public void setFontName( Font initialFont ) {
      for ( int i=0; i<availableFonts.length; i++ ) {
         if ( availableFonts[i].equals( 
                           initialFont.getName() ) ) {
            fontChoices.select( i );
         }
      }
   }
}