JLabel transferhandler 复制工作但不移动

Question

I want to move text from one jlabel onto another, but for some reason, only copy is working and not move. I am using a transferhandler so in handler.exportAsDrag(comp, e, TransferHandler.MOVE); only TransferHandler.COPY works.

            add1 = new JLabel("", JLabel.CENTER);
        add1.setTransferHandler(new TransferHandler("text"));
        add1.setBorder(b2);


        add2 = new JLabel("", JLabel.CENTER);
        add2.setTransferHandler(new TransferHandler("text"));
        add2.setBorder(b2);

            MouseListener listener = new DragMouseAdapter();

        add1.addMouseListener(listener);
        add2.addMouseListener(listener);

            panel2a.add(add1);

        panel2a.add(add2);

They are dragged using this private inner class

private class DragMouseAdapter extends MouseAdapter
    {
        public void mousePressed(MouseEvent e)
        {
            JComponent comp = (JComponent)e.getSource();
            TransferHandler handler = comp.getTransferHandler();

            //c.setOpaque(true);
            handler.exportAsDrag(comp, e, TransferHandler.MOVE);

        }


    }

Answer 1

The implementation of TransferHandler.getSourceActions() by default returns COPY if the specified property exists and has a proper getter:

public int getSourceActions(JComponent c) {
PropertyDescriptor prop = getPropertyDescriptor(c);
if (prop != null) {
    return COPY;
}
return NONE;
}

As a result, when you specify MOVE in exportAsDrag() the handler decides the action is not supported.

You can override this method to add whatever actions your source supports. For example:

add1.setTransferHandler(new TransferHandler("text") {
    @Override
    public int getSourceActions(JComponent c) {
        return COPY | MOVE;
    }
});

EDIT: implement exportDone

this.setTransferHandler(new TransferHandler("text") {
    @Override
    protected void exportDone(JComponent source, Transferable data, int action) {
        if (action == MOVE){
            ((JLabel) source).setText("");
        }
    }

    @Override
    public int getSourceActions(JComponent c) {
        return COPY | MOVE;
    }
});