我有两个组件，每个组件都有自己的MouseMotionListener。当我在拖动第一个Component的同时将鼠标从第一个Component移动到第二个Component时，似乎第二个Component的MouseMotionListener被禁用，即我将鼠标移动到第二个组件上时根本不会调用mouseMoved。如何避免“禁用”？
示例：
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class DragTest implements MouseMotionListener {
private static JPanel p1 = new JPanel();
private static JPanel p2 = new JPanel();
public DragTest() {
}
public static void main(String[] args) {
p1.setBackground(Color.RED);
p1.addMouseMotionListener(new DragTest());
p2.setBackground(Color.BLUE);
p2.addMouseMotionListener(new DragTest());
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(100, 100, 600, 300);
frame.setLayout(new GridLayout(1, 2));
frame.add(p1);
frame.add(p2);
frame.setVisible(true);
}
@Override
public void mouseMoved(MouseEvent e) {
if (e.getSource() == p1) {
System.out.println("mouse movement in p1");
} else if (e.getSource() == p2) {
System.out.println("mouse movement in p2");
}
}
@Override
public void mouseDragged(MouseEvent e) {
if (e.getSource() == p1) {
System.out.println("mouse drag in p1");
} else if (e.getSource() == p2) {
System.out.println("mouse drag in p2");
}
}
}
答案 0 :(得分：1)
免责声明：这是核心拖放API的一个非常非常基本的示例，它基于this example和this example和{ {3}}旨在简单地证明确定规定跌落位置的可能性
因此，当涉及拖动内容时，特别是跨组件时，使用拖放API而不是简单地使用MouseMotionListener和MouseListener通常会更好。这就是API的设计目的，并向两个目标提供有关操作性质的通知
以下示例仅存储您放置内容的位置，并在那里绘制一个漂亮的小点
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragSource;
import java.awt.dnd.DragSourceDragEvent;
import java.awt.dnd.DragSourceDropEvent;
import java.awt.dnd.DragSourceEvent;
import java.awt.dnd.DragSourceListener;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;
import java.awt.dnd.DropTargetEvent;
import java.awt.dnd.DropTargetListener;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
import javax.swing.border.MatteBorder;
public class DragAndDropTest {
public static void main(String[] args) {
new DragAndDropTest();
}
public DragAndDropTest() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridLayout(1, 2));
add(new DropPane());
add(new DragPane());
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.dispose();
}
}
public class DragPane extends JPanel {
private DragSource ds;
private Transferable transferable;
public DragPane() {
ds = new DragSource();
transferable = new Transferable() {
@Override
public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[]{DataFlavor.stringFlavor};
}
@Override
public boolean isDataFlavorSupported(DataFlavor flavor) {
return DataFlavor.stringFlavor.equals(flavor);
}
@Override
public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException, IOException {
return "This is a test";
}
};
ds.createDefaultDragGestureRecognizer(this, DnDConstants.ACTION_COPY_OR_MOVE, new DragGestureListener() {
@Override
public void dragGestureRecognized(DragGestureEvent dge) {
// This is where you would export the data you want
// to transfer
ds.startDrag(dge, DragSource.DefaultCopyDrop, transferable, new DragSourceListener() {
@Override
public void dragEnter(DragSourceDragEvent dsde) {
}
@Override
public void dragOver(DragSourceDragEvent dsde) {
}
@Override
public void dropActionChanged(DragSourceDragEvent dsde) {
}
@Override
public void dragExit(DragSourceEvent dse) {
}
@Override
public void dragDropEnd(DragSourceDropEvent dsde) {
}
});
}
});
setLayout(new GridBagLayout());
add(new JLabel("Drag from here"));
setBorder(new LineBorder(Color.RED));
}
}
public class DropPane extends JPanel {
private List<Point> dropPoints;
public DropPane() {
dropPoints = new ArrayList<>(25);
setDropTarget(new DropTarget(this, new DropTargetListener() {
@Override
public void dragEnter(DropTargetDragEvent dtde) {
}
@Override
public void dragOver(DropTargetDragEvent dtde) {
}
@Override
public void dropActionChanged(DropTargetDragEvent dtde) {
}
@Override
public void dragExit(DropTargetEvent dte) {
}
@Override
public void drop(DropTargetDropEvent dtde) {
// Normally here, I'd inspect the Transferable and make sure
// what is been dropped and can be imported, I'd then go through
// the process of unwrapping the data from the Transferable and
// processing it appropriatly, but in this example, I really don't
// care, I just care about WHERE the event occured
dropPoints.add(dtde.getLocation());
dtde.dropComplete(true);
repaint();
}
}));
setLayout(new GridBagLayout());
add(new JLabel("Drop to here"));
setBorder(new MatteBorder(1, 1, 1, 0, Color.RED));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.RED);
for (Point p : dropPoints) {
g.fillOval(p.x - 2, p.y - 2, 5, 5);
}
}
}
}