mytransferhandler.java

Java 简易小相册.帮你理解Drag and Drop 的功能.

import java.awt.Image;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;

import javax.swing.JComponent;
import javax.swing.TransferHandler;
/*
 * Created on 1/07/2006
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

/**
 * @author Xuesong Le
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class MyTransferHandler extends TransferHandler
{

    private static final long serialVersionUID = 1L;
    MyPicComponent
    	sourceComp = null;
    boolean
    	shouldRemove = false;	
    public boolean canImport(JComponent comp,DataFlavor[] transferFlavors)
    {
        for(int i=0; i< transferFlavors.length; i++)
        {
            if(transferFlavors[i].equals(DataFlavor.imageFlavor))
            {
                return true;
            }
            
        }// End for
        
        return false;
    }
    
    public boolean importData(JComponent comp,Transferable t)
    {
        if( canImport(comp,t.getTransferDataFlavors()))
        {
            // Check data holding in Transferable t is same as that in comp
            MyPicComponent
            	pic = (MyPicComponent)comp;
            //Don't drop on myself.
            if (sourceComp == pic) 
            {
                shouldRemove = false;
                return true;
            }
            else
            {
                try
                {
                    // Get Transferable Data from t
                    Image
                		img = (Image)t.getTransferData(DataFlavor.imageFlavor);
                    // Import Data
                    pic.setImage(img);
                    return true;
                }
                catch (UnsupportedFlavorException ufe) 
                {
                    System.out.println("importData: unsupported data flavor");
                } 
                catch (IOException ioe) 
                {
                    System.out.println("importData: I/O exception");
                }
            }
            
        }
        
        return false;
        
        
    }
    
    protected void exportDone(JComponent source,Transferable data,int action)
    {
        if( shouldRemove == true && action == MOVE)
        {
            MyPicComponent
            	sourceComp = (MyPicComponent)source;
            sourceComp.setImage(null);
        }
        return;
    }
    
    protected Transferable createTransferable(JComponent c)
    {
        sourceComp = (MyPicComponent)c;
        shouldRemove = true;
        
        return new MyPicTransferable(sourceComp); 
    }
    
    public int getSourceActions(JComponent c)
    {
        return COPY_OR_MOVE;
    }
    
    public static void main(String[] args)
    {
        
    }
}