我有一个swing应用程序，我想通过将外部文件从Windows资源管理器拖到应用程序中来导入外部文件。我已经实现了这个基本功能。但是，我想将默认的拖放光标图标变成适合应用程序的光标。我尝试过使用DragGestureListener和DragSource来完成这个任务，但却没有成功。如果拖放操作是在同一个swing应用程序内进行，则可以看到这种方法运行的示例。但是，当拖放源在Swing之外时，这些方法似乎不会被调用。在将外部文件拖入swing应用程序时，是否可能更改拖动光标？请参考以下简化示例：
public class DnDTemplate extends JFrame {
private static final long serialVersionUID = 1L;
private JComponent thePane = null;
private Cursor dropCursor = null;
public DnDTemplate() {
super( "Drop File Here" );
thePane = (JComponent) getContentPane();
thePane.setTransferHandler( new DndTransferHandler() );
ImageIcon imageIcon = new ImageIcon( "drop_here.gif" );
Image image = imageIcon.getImage();
BufferedImage bufferedImage = new BufferedImage( 16, 16, BufferedImage.TYPE_INT_ARGB );
Graphics graphics = bufferedImage.getGraphics();
graphics.drawImage( image, 0, 0, null );
dropCursor = Toolkit.getDefaultToolkit().createCustomCursor( bufferedImage, new Point( 16, 16 ), "drop cursor" );
setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
setSize( 300, 300 );
}
public static void main( String[] args ) {
new DnDTemplate().setVisible( true );
}
class DndTransferHandler extends TransferHandler {
private static final long serialVersionUID = 1L;
@Override
public boolean canImport( TransferHandler.TransferSupport info ) {
// This gets called repeatedly while dragged file is over frame
if ( !info.isDataFlavorSupported( DataFlavor.javaFileListFlavor ) ) {
return false;
}
// Even though this method is called at the appropriate time,
// setting the cursor here is of no consequence
info.getComponent().setCursor( dropCursor );
return true;
}
@Override
public boolean importData( TransferHandler.TransferSupport info ) {
// this gets called when file is dropped
if ( !info.isDrop() ) {
return false;
}
Transferable transferable = info.getTransferable();
String importFileName = null;
try {
List<File> fileList = (List<File>) transferable.getTransferData( DataFlavor.javaFileListFlavor );
Iterator<File> iterator = fileList.iterator();
while ( iterator.hasNext() ) {
File f = iterator.next();
importFileName = f.getAbsolutePath();
}
info.getComponent().setCursor( dropCursor );
thePane.setCursor( dropCursor );
} catch ( Exception e ) {
return false;
}
System.out.println( "Importing " + importFileName );
// Return the cursor back to the default
thePane.setCursor( Cursor.getPredefinedCursor( Cursor.DEFAULT_CURSOR ) );
return true;
}
}
}