Java Swing中的实时拖放

我使用swing中的拖放功能在四个组件之一上放置一个按钮。为了使它更吸引人，而不仅仅是鼠标指示正在拖动的东西，这很好，我想实时显示它。除非鼠标回到被拖动的组件上，拖动侦听器会注册一个dragExit事件，该事件会删除使侦听器重新聚焦到父组件上的按钮，并触发一个拖动器，导致闪烁。我需要使按钮不影响拖动侦听器。有什么想法吗

这是jlabel，我也在添加它，我知道jlabel不是一个好选择，但它工作良好，可以轻松显示我需要的图像

import java.awt.Point;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.*;
import java.io.IOException;
import javax.swing.*;


//and here is the button to drag   
public class DndLabel extends JLabel implements DropTargetListener {

    private DropTarget target;
    private DndButton button;
    public DndLabel last;

    //initialize the JTable with the data
    public DndLabel() {
        super();

        //mark this a DropTarget
        target = new DropTarget(this, this);

        //have it utilize a custom transfer handler
        setTransferHandler(new MyTransferHandler());
    }

    public void dragEnter(DropTargetDragEvent dtde) {
        System.out.println("enter");

        try {
            //get the Point where the drop occurred
            Point loc = dtde.getLocation();

            //get Transfer data
            Transferable t = dtde.getTransferable();

            //get the Data flavors transferred with the Transferable
            DataFlavor[] d = t.getTransferDataFlavors();

            button = (DndButton) t.getTransferData(d[0]);

            button.setBounds(loc.x, 0, 100, 50);

            add(button);

            //and if the DataFlavors match for the DnDTable 
            //(ie., we don't want an ImageFlavor marking an image transfer)
            if (getTransferHandler().canImport(this, d)) {

                //then import the Draggable JComponent and repaint() the JTable
                ((MyTransferHandler) getTransferHandler()).importData(this, (DndButton) t.getTransferData(d[0]), loc);
                repaint();
            } else {
                return;
            }
        } catch (UnsupportedFlavorException  ex) {
            ex.printStackTrace();
        } catch(IOException ex){
            ex.printStackTrace();
        }
    }

    @Override
    public void dragOver(DropTargetDragEvent dtde) {
        button.setLocation(dtde.getLocation().x, 0);
    }

    public void dragExit(DropTargetEvent dte) {
        System.out.println("remove");

        last = null;
        remove(button);
        repaint();

    }

    //This is what happens when a Drop occurs
    public void drop(DropTargetDropEvent dtde) {
        System.out.println("drop!");
        try {
            //get the Point where the drop occurred
            Point loc = dtde.getLocation();

            //get Transfer data
            Transferable t = dtde.getTransferable();

            //get the Data flavors transferred with the Transferable
            DataFlavor[] d = t.getTransferDataFlavors();

            DndButton tempButton = (DndButton) t.getTransferData(d[0]);

            tempButton.setBounds(loc.x, 0, 100, 50);

            add(tempButton);

            //and if the DataFlavors match for the DnDTable 
            //(ie., we don't want an ImageFlavor marking an image transfer)
            if (getTransferHandler().canImport(this, d)) {

                //then import the Draggable JComponent and repaint() the JTable
                ((MyTransferHandler) getTransferHandler()).importData(this, (DndButton) t.getTransferData(d[0]), loc);
                repaint();
            } else {
                return;
            }

        } catch (UnsupportedFlavorException ex) {
            ex.printStackTrace();
        }catch(IOException ex){

        }finally {
            dtde.dropComplete(true);
        }
    }

    @Override
    public void dropActionChanged(DropTargetDragEvent dtde) {
    }

    class MyTransferHandler extends TransferHandler {

        //tests for a valid JButton DataFlavor
        public boolean canImport(JComponent c, DataFlavor[] f) {
            DataFlavor temp = new DataFlavor(DndButton.class, "JButton");
            for (DataFlavor d : f) {
                if (d.equals(temp)) {
                    return true;
                }

            }
            return false;
        }

        //add the data into the JTable
        public boolean importData(JComponent comp, Transferable t, Point p) {
            try {
                DndButton tempButton = (DndButton) t.getTransferData(new DataFlavor(DndButton.class, "JButton"));

            } catch (UnsupportedFlavorException | IOException ex) {
                System.err.println(ex);
            }
            return true;
        }
    }
}
class DndButton extends JButton implements Transferable, DragSourceListener, DragGestureListener {

    //marks this JButton as the source of the Drag
    private DragSource source;
    private TransferHandler t;

    public DndButton() {
        this("");
    }

    public DndButton(String message) {
        super(message);

        //The TransferHandler returns a new DnDButton
        //to be transferred in the Drag
        t = new TransferHandler() {

            public Transferable createTransferable(JComponent c) {
                return new DndButton(getText());
            }
        };
        setTransferHandler(t);

        //The Drag will copy the DnDButton rather than moving it
        source = new DragSource();
        source.createDefaultDragGestureRecognizer(this, DnDConstants.ACTION_MOVE, this);
    }

    //The DataFlavor is a marker to let the DropTarget know how to
    //handle the Transferable
    public DataFlavor[] getTransferDataFlavors() {
        return new DataFlavor[]{new DataFlavor(DndButton.class, "JButton")};
    }

    public boolean isDataFlavorSupported(DataFlavor flavor) {
        return true;
    }

    public Object getTransferData(DataFlavor flavor) {
        return this;
    }

    public void dragEnter(DragSourceDragEvent dsde) {
    }

    public void dragOver(DragSourceDragEvent dsde) {
        //this.setLocation(dsde.getX()-150,0);
    }

    public void dropActionchanged(DragSourceDragEvent dsde) {
    }

    public void dragExit(DragSourceEvent dse) {
    }

    //when the drag finishes, then repaint the DnDButton
    //so it doesn't look like it has still been pressed down
    public void dragDropEnd(DragSourceDropEvent dsde) {
        // JComponent c = (JComponent) this.getParent();
        //c.remove(this);
        //c.repaint();
    }

    //when a DragGesture is recognized, initiate the Drag
    public void dragGestureRecognized(DragGestureEvent dge) {
        source.startDrag(dge, DragSource.DefaultMoveDrop, DndButton.this, this);
    }

    @Override
    public void dropActionChanged(DragSourceDragEvent dsde) {
    }
}

class Main {

    public static void main(String[] args) {
        JFrame f = new JFrame("sscce");
        f.setBounds(0, 0, 500, 80);
        f.setVisible(true);
        DndLabel trackOne = new DndLabel();
        trackOne.setBounds(0, 0, 500, 50);
        f.add(trackOne);
        DndButton b = new DndButton("hello");
        b.setBounds(0, 0, 100, trackOne.getHeight());

        trackOne.add(b);
        trackOne.revalidate();
        trackOne.repaint();
    }
}

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一、 就个人而言，他可能会抵制这样做。问题是，每次添加组件时，组件都会干扰层次结构中的鼠标侦听器，导致容器收到退出事件的通知，从而导致按钮被删除，容器收到enter事件的通知，并且循环继续

就我个人而言，我会做两件事中的一件。我也会

在玻璃窗格上绘制按钮或按钮的图示 在“拖动”面板上绘制按钮的表示形式 这消除了按钮对相关鼠标侦听器造成干扰的可能性

---

退房。当你在那里翻来覆去的时候，Tim写了很多关于drag'n'drop的优秀文章，值得一读

我个人可能会抵制这样做。问题是，每次添加组件时，组件都会干扰层次结构中的鼠标侦听器，导致容器收到退出事件的通知，从而导致按钮被删除，容器收到enter事件的通知，并且循环继续

就我个人而言，我会做两件事中的一件。我也会

在玻璃窗格上绘制按钮或按钮的图示 在“拖动”面板上绘制按钮的表示形式 这消除了按钮对相关鼠标侦听器造成干扰的可能性

---

退房。当你在那里翻找的时候，Tim写了很多关于drag'n'drop的优秀文章，值得一读。

为了更快地获得更好的帮助，请发布一篇。@Andrew Thompson好的，我将代码更改为SSCCEYeah，我喜欢Tim的东西，真的帮助了我是的，我喜欢蒂姆的东西，真的帮助了我