localtransfertest.java

java核心技术源代码

/**
   @version 1.00 2001-08-11
   @author Cay Horstmann
*/

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.io.*;
import java.util.*;
import javax.swing.*;

/**
   This program demonstrates the transfer of object references
   within the same virtual machine.
*/
public class LocalTransferTest
{  
   public static void main(String[] args)
   {  
      JFrame frame = new LocalTransferFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.show();
   }
}

/**
   This frame contains a panel to edit a cubic curve, a
   panel that can display an arbitrary shape, and copy and 
   paste buttons.
*/
class LocalTransferFrame extends JFrame
{  
   public LocalTransferFrame()
   {  
      setTitle("LocalTransferTest");
      setSize(WIDTH, HEIGHT);

      Container contentPane = getContentPane();

      curvePanel = new CubicCurvePanel();
      curvePanel.setPreferredSize(new Dimension(WIDTH / 2, 
         HEIGHT));
      shapePanel = new ShapePanel();

      contentPane.add(new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
         curvePanel, shapePanel), BorderLayout.CENTER);
      JPanel panel = new JPanel();

      JButton copyButton = new JButton("Copy");
      panel.add(copyButton);
      copyButton.addActionListener(new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               copy();
            }
         });

      JButton pasteButton = new JButton("Paste");
      panel.add(pasteButton);
      pasteButton.addActionListener(new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               paste();
            }
         });

      contentPane.add(panel, BorderLayout.SOUTH);
   }

   /**
      Copies the current cubic curve to the local clipboard.
   */
   private void copy()
   {  
      LocalSelection selection = new LocalSelection(
         curvePanel.getShape());
      clipboard.setContents(selection, null);
   }

   /**
      Pastes the shape from the local clipboard into the
      shape panel.
   */
   private void paste()
   {  
      Transferable contents = clipboard.getContents(null);
      if (contents == null) return;
      try
      {  
         DataFlavor flavor = new DataFlavor(
"application/x-java-jvm-local-objectref;class=java.awt.Shape");
         if (contents.isDataFlavorSupported(flavor))
            shapePanel.setShape(
               (Shape)contents.getTransferData(flavor));
      }
      catch(ClassNotFoundException exception)
      {  
         JOptionPane.showMessageDialog(this, exception);
      }
      catch(UnsupportedFlavorException exception)
      {  
         JOptionPane.showMessageDialog(this, exception);
      }
      catch(IOException exception)
      {  
         JOptionPane.showMessageDialog(this, exception);
      }
   }

   private CubicCurvePanel curvePanel;
   private ShapePanel shapePanel;
   private Clipboard clipboard = new Clipboard("local");

   private static final int WIDTH = 300;
   private static final int HEIGHT = 300;
}


/**
   This panel draws a shape and allows the user to 
   move the points that define it.
*/
class CubicCurvePanel extends JPanel
{  
   public CubicCurvePanel()
   {  
      addMouseListener(new
         MouseAdapter()
         {
            public void mousePressed(MouseEvent event)
            {  
               for (int i = 0; i < p.length; i++)
               {  
                  double x = p[i].getX() - SIZE / 2;
                  double y = p[i].getY() - SIZE / 2;
                  Rectangle2D r 
                     = new Rectangle2D.Double(x, y, SIZE, SIZE);
                  if (r.contains(event.getPoint()))
                  {  
                     current = i;
                     return;
                  }
               }
            }

            public void mouseReleased(MouseEvent event)
            {  
               current = -1;
            }
         });

      addMouseMotionListener(new 
         MouseMotionAdapter()
         {
            public void mouseDragged(MouseEvent event)
            {  
               if (current == -1) return;
               p[current] = event.getPoint();
               repaint();
            }
         });

      current = -1;
   }

   public void paintComponent(Graphics g)
   {  
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D)g;
      for (int i = 0; i < p.length; i++)
      {  
         double x = p[i].getX() - SIZE / 2;
         double y = p[i].getY() - SIZE / 2;
         g2.fill(new Rectangle2D.Double(x, y, SIZE, SIZE));
      }

      g2.draw(getShape());
   }

   /**
      Gets the current cubic curve.
      @return the curve shape
   */
   public Shape getShape()
   {  
      return new CubicCurve2D.Double(p[0].getX(), p[0].getY(),
         p[1].getX(), p[1].getY(), p[2].getX(), p[2].getY(),
         p[3].getX(), p[3].getY());
   }

   private Point2D[] p =   
   {
      new Point2D.Double(10, 10), 
      new Point2D.Double(10, 100), 
      new Point2D.Double(100, 10), 
      new Point2D.Double(100, 200)
   };
   private static int SIZE = 10;
   private int current;
}

/**
   This panel displays an arbitrary shape.
*/
class ShapePanel extends JPanel
{
   /**
      Set the shape to be displayed in this panel.
      @param aShape any shape
   */
   public void setShape(Shape aShape)
   {
      shape = aShape;
      repaint();
   }

   public void paintComponent(Graphics g)
   {  
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D)g;
      if (shape != null) g2.draw(shape);
   }

   private Shape shape;
}

/**
   This class is a wrapper for the data transfer of 
   object references that are transferred within the same
   virtual machine.
*/
class LocalSelection implements Transferable 
{
   /**
      Constructs the selection.
      @param o any object
   */   
   LocalSelection(Object o) 
   {
      obj = o;
   }

   public DataFlavor[] getTransferDataFlavors() 
   {
      DataFlavor[] flavors = new DataFlavor[1];
      Class type = obj.getClass();
      String mimeType 
         = "application/x-java-jvm-local-objectref;class=" 
         + type.getName();
      try 
      {
         flavors[0] = new DataFlavor(mimeType);
         return flavors;
      } 
      catch (ClassNotFoundException exception) 
      {
         return new DataFlavor[0];
      }
   }

   public boolean isDataFlavorSupported(DataFlavor flavor) 
   {
      return "application".equals(flavor.getPrimaryType()) 
         && "x-java-jvm-local-objectref".equals(
            flavor.getSubType()) 
         && flavor.getRepresentationClass().isAssignableFrom(
            obj.getClass());   
   }

   public Object getTransferData(DataFlavor flavor) 
      throws UnsupportedFlavorException
   {
      if (! isDataFlavorSupported(flavor)) 
         throw new UnsupportedFlavorException(flavor);

      return obj;
   }
   
   private Object obj;
}