dragdropdemo.java

java 完全探索的随书源码

// DragDropDemo.java

import javax.swing.*;

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.event.*;

class DragDropDemo extends JFrame
                   implements ActionListener, DropTargetListener
{
   DragLabel source = new DragLabel ("Text", JLabel.CENTER);
   JButton target = new JButton ();

   DragDropDemo (String title)
   {
      super (title);

      addWindowListener (new WindowAdapter ()
                         {
                             public void windowClosing (WindowEvent e)
                             {
                                System.exit (0);
                             }
                         });

      source.setForeground (Color.red);
      getContentPane ().add (source, BorderLayout.NORTH);

      target.addActionListener (this);
      getContentPane ().add (target, BorderLayout.SOUTH);

      new DropTarget (target,
                      DnDConstants.ACTION_COPY_OR_MOVE,
                      this);

      setSize (205, 100);

      setVisible (true);
   }

   public void actionPerformed (ActionEvent e)
   {
      JButton b = (JButton) e.getSource ();
      b.setText ("");
      source.setText ("Text");
   }

   public void dragEnter (DropTargetDragEvent e)
   {
      System.out.println ("Entering drop target #1");
   }

   public void dragExit (DropTargetEvent e)
   {
      System.out.println ("Exiting drop target #1");
   }

   public void dragOver (DropTargetDragEvent e)
   {
      System.out.println ("Dragging over drop target #1");
   }

   public void drop (DropTargetDropEvent e)
   {
      System.out.println ("Dropping");

      try
      {
          Transferable t = e.getTransferable ();

          if (e.isDataFlavorSupported (DataFlavor.stringFlavor))
          {
              e.acceptDrop (e.getDropAction ());

              String s;
              s = (String) t.getTransferData (DataFlavor.stringFlavor);

              target.setText (s);

              e.dropComplete (true);
          }
          else
              e.rejectDrop ();
      }
      catch (java.io.IOException e2) {}
      catch (UnsupportedFlavorException e2) {}
   }

   public void dropActionChanged (DropTargetDragEvent e)
   {
      System.out.println ("Drop action changed #1");
   }

   public static void main (String [] args)
   {
      new DragDropDemo ("Drag and Drop Demo");
   }
}

class DragLabel extends JLabel implements DragGestureListener,
                                          DragSourceListener
{
   private DragSource ds = DragSource.getDefaultDragSource ();

   public DragLabel (String s, int alignment)
   {
      super (s, alignment);

      int action = DnDConstants.ACTION_COPY_OR_MOVE;
      ds.createDefaultDragGestureRecognizer (this,
                                             action,
                                             this);
   }

   public void dragGestureRecognized (DragGestureEvent e)
   {
      try
      {
          Transferable t = new StringSelection (getText ());

          e.startDrag (DragSource.DefaultCopyNoDrop, t, this);
      }
      catch (InvalidDnDOperationException e2)
      {
         System.out.println (e2);
      }
   }

   public void dragDropEnd (DragSourceDropEvent e)
   {
      System.out.println ("Drag and drop end");

      if (e.getDropSuccess () == false)
      {
          System.out.println ("unsuccessful");
          return;
      }

      int action = e.getDropAction ();
      if ((action & DnDConstants.ACTION_MOVE) != 0)
          setText ("");
   }

   public void dragEnter (DragSourceDragEvent e)
   {
      System.out.println ("Entering drop target #2");

      DragSourceContext ctx = e.getDragSourceContext ();

      int action = e.getDropAction ();
      if ((action & DnDConstants.ACTION_COPY) != 0)
          ctx.setCursor (DragSource.DefaultCopyDrop);
      else
          ctx.setCursor (DragSource.DefaultCopyNoDrop);
   }

   public void dragExit (DragSourceEvent e)
   {
      System.out.println ("Exiting drop target #2");
   }

   public void dragOver (DragSourceDragEvent e)
   {
      System.out.println ("Dragging over drop target #2");
   }

   public void dropActionChanged (DragSourceDragEvent e)
   {
      System.out.println ("Drop action changed #2");
   }
}