hexviewer.java

一个用java写的mail.里面的代码值得我们去研究！学习。

    label.setBorder( new EmptyBorder( 0, 2, 0, 2 ) );
    AWTUtilities.constrain( ctlPanel, label, GridBagConstraints.NONE,
                            GridBagConstraints.CENTER, ctlCol++, ctlRow, 1, 1, 0.0, 0.0 );

    this.blkHexField = new JTextField();
    AWTUtilities.constrain( ctlPanel, this.blkHexField, GridBagConstraints.HORIZONTAL,
                            GridBagConstraints.CENTER, ctlCol++, ctlRow, 1, 1, 0.2, 0.0 );

    this.blkDecField = new JTextField();
    AWTUtilities.constrain( ctlPanel, this.blkDecField, GridBagConstraints.HORIZONTAL,
                            GridBagConstraints.CENTER, ctlCol++, ctlRow, 1, 1, 0.25, 0.0 );

    label = new JLabel( "Offset:" );
    label.setHorizontalAlignment( JLabel.RIGHT );
    label.setBorder( new EmptyBorder( 0, 8, 0, 2 ) );
    AWTUtilities.constrain( ctlPanel, label, GridBagConstraints.NONE,
                            GridBagConstraints.CENTER, ctlCol++, ctlRow, 1, 1, 0.0, 0.0 );

    this.offHexField = new JTextField();
    AWTUtilities.constrain( ctlPanel, this.offHexField, GridBagConstraints.HORIZONTAL,
                            GridBagConstraints.CENTER, ctlCol++, ctlRow, 1, 1, 0.2, 0.0 );

    this.offDecField = new JTextField();
    AWTUtilities.constrain( ctlPanel, this.offDecField, GridBagConstraints.HORIZONTAL,
                            GridBagConstraints.CENTER, ctlCol++, ctlRow++, 1, 1, 0.35, 0.0 );

    JPanel dataPanel = new JPanel();
    dataPanel.setLayout( new GridBagLayout() );
    dataPanel.setBorder( new EmptyBorder( 2, 2, 2, 2 ) );
    AWTUtilities.constrain( this, dataPanel, GridBagConstraints.BOTH,
                            GridBagConstraints.CENTER, 0, row++, 1, 1, 1.0, 1.0 );

    this.scrollBar = new JScrollBar( JScrollBar.HORIZONTAL, 0, 1, 0, 1 );

    this.scrollBar.setBlockIncrement( HexViewer.PAGEINCR );
    this.scrollBar.getModel().addChangeListener( new IChangeListener() );

    AWTUtilities.constrain( dataPanel, this.scrollBar, GridBagConstraints.HORIZONTAL,
                            GridBagConstraints.CENTER, 0, 0, 1, 1, 1.0, 0.0 );

    this.hexCanvas = new HexCanvas();
    this.hexCanvas.setOpaque( true );
    this.hexCanvas.setBackground( Color.white );
    this.hexCanvas.setBorder( new EmptyBorder( 0, 8, 0, 2 ) );
    this.hexCanvas.setFont( new Font( "Monospaced", Font.PLAIN, 12 ) );

    AWTUtilities.constrain( dataPanel, this.hexCanvas, GridBagConstraints.BOTH,
                            GridBagConstraints.CENTER, 0, 1, 1, 1, 1.0, 1.0 );
  }

  private void
  resetCursor() {
    Frame f = (Frame)getTopLevelAncestor();
    if ( f != null && this.saveCursor != null )
      f.setCursor( this.saveCursor );
    this.saveCursor = null;
  }

  private void
  setWaitCursor() {
    Frame f = (Frame)getTopLevelAncestor();
    if ( f != null ) {
      this.saveCursor = f.getCursor();
      f.setCursor( Cursor.getPredefinedCursor( Cursor.WAIT_CURSOR ) );
    }
  }

//............................................................
// INNER CLASSES

  private class HexCanvas
    extends JComponent
  {
    private int             hexHeight;
    private int             hexByteW;
    private int             hexQuadW;
    private int             hexDataW;
    private int             hexSepW;
    private int             hexCharW;
    private int             hexLineW;
    private int             spaceW;
    private int             offsetW;

    private Dimension       mDim;
    private Dimension       pDim;

    private boolean         displayEOF;
    private byte[]          data;

    private HexNumberFormat format;


    public
    HexCanvas() {
      super();
      this.data = null;
      this.displayEOF = false;
      this.mDim = new Dimension( 20, 20 );
      this.pDim = new Dimension( 400, 400 );
      this.format = new HexNumberFormat( "XX" );
    }

    public boolean
    isFocusTraversable() {
      return false;
    }

    public void
    displayEOF() {
      this.data = null;
      this.displayEOF = true;
      repaint( 500 );
    }

    public void
    displayData( byte[] data ) {
      this.data = data;
      this.displayEOF = false;
      repaint( 500 );
    }

    public void
    update( Graphics updateG ) {
      paint( updateG );
    }

    public synchronized void
    paint( Graphics g ) {
      int     i, j;
      int     top, left;
      int     width, height;
      int     x, y;

      Dimension   sz = getSize();

      if ( this.isOpaque() ) {
        g.setColor( getBackground() );
        g.fillRect( 0, 0, sz.width, sz.height );
      }

      g.setColor( getForeground() );

      Font fHex = getFont();
      Font fTitle = getFont();

      x = 1;
      y = this.hexHeight + 1;

      if ( this.displayEOF ) {
      // UNDONE This is HORRIBLY inefficient!
        g.setFont( new Font( "Serif", Font.BOLD, 18 ) );
        FontMetrics fm = g.getFontMetrics( g.getFont() );
        String msg = "End Of Data";
        int sW = fm.stringWidth( msg );
        x = (sz.width - sW) / 2;
        y = ((sz.height - fm.getHeight()) / 2) + fm.getHeight();
        g.drawString( msg, x, y );
        return;
      } else if ( this.data == null ) {
        return;
      }

      int cnt = 0;
      g.setFont( fHex );
      for ( i = 0 ; i < HexViewer.HEXLINES && cnt < this.data.length ; ++i ) {
        StringBuffer buf = new StringBuffer();
        StringBuffer chBuf = new StringBuffer();
        FieldPosition pos = new FieldPosition(0);

        this.format.format( new Integer(i * HexViewer.HEXBYTES), buf, pos );
        buf.append( ": " );

        for ( j = 0 ; j < HexViewer.HEXBYTES && cnt < this.data.length ; ++j, ++cnt ) {
          int index = (i * HexViewer.HEXBYTES) + j;

          if ( index >= this.data.length )
            break;

          char ch = (char)this.data[ index ];
          chBuf.append( (ch >= 32 && ch < 127) ? ch : '.' );

          this.format.format( new Integer( this.data[index] ), buf, pos );

          buf.append( " " );
        }
        
        for ( ; j < HexViewer.HEXBYTES ; ++j ) {
          buf.append( "   " );
        }

        buf.append( " " );
        buf.append( chBuf );

        g.drawString( buf.toString(), x, y );

        y += this.hexHeight;
      }
    }

    public void
    addNotify() {
      super.addNotify();
      computeDimensions();
    }
    
    public void
    setFont( Font f ) {
      super.setFont( f );

      Graphics g = getGraphics();
      if ( g != null ) {
        establishFontMetrics( g, f );
      }
    }

    private void
    establishFontMetrics( Graphics g, Font f ) {
      FontMetrics fm = g.getFontMetrics( getFont() );
      this.hexHeight = fm.getLeading() + fm.getAscent();
        
      this.spaceW = fm.stringWidth( " " );
      this.offsetW = fm.stringWidth( "88: " );
      this.hexByteW = fm.stringWidth( "88" );
      this.hexQuadW = (4 * hexByteW) + (3 * this.spaceW);

      this.hexDataW = (4 * hexQuadW);

      this.hexSepW = fm.stringWidth( "  " );

      this.hexCharW = fm.stringWidth( "0123456789ABCDEF" );

      this.hexLineW = this.offsetW + this.hexDataW + this.hexSepW + this.hexCharW;
    }

    public void
    computeDimensions() {
      int     width, height;
      Dimension sz = getSize();
      Graphics  g = getGraphics();
      
      establishFontMetrics( g, getFont() );

      width = this.hexLineW + 2;
      height = (HexViewer.HEXLINES * this.hexHeight) + 2;
      
      this.mDim.width = width;
      this.mDim.height = height;
      
      this.pDim.width = mDim.width;
      this.pDim.height = mDim.height;
    }

    public Dimension
    getPreferredSize() {
      return pDim;
    }

    public Dimension
    getMinimumSize() {
      return pDim;
    }

  }

//............................................................

  private class IChangeListener
    implements ChangeListener
  {
    public void
    stateChanged( ChangeEvent event ) {
      int value = scrollBar.getValue();
      setCurrentBlock( value * BLOCKSIZE );
    }
  }

}