Java 拖放和鼠标监听器

Question

我在触摸界面中使用如下逻辑，因此我希望能够使用 mousePressed 来启动拖动，但同时如果用户不拖动，则能够使用 mouseClicked 或 mouseReleased 。

在 mousePressed 上，我开始拖动。在 mouseClicked 上，我希望它打印出“mouseClicked”，并在“mouseReleased”上打印 mouseReleased，但由于某种原因

    dropLabel.getTransferHandler().exportAsDrag(dropLabel, e,
            TransferHandler.COPY);

吞下导致 mouseClicked 和 mouseReleased 事件不会被触发的事件，即使我不移动鼠标也是如此。请注意，注释掉该行会导致所有监听器被触发(但显然拖动并未开始)。

如何让所有鼠标事件按照我想要的方式发生，特别是当用户不进行任何拖动时的 mouseClicked/mouseReleased，同时在用户进行拖动时仍然能够导出AsDragged？欢迎任何黑客/裂缝/反射解决方案。

这是我正在使用的一些示例代码，它说明了我的实际问题:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.TransferHandler;

public class DragTest extends JFrame implements MouseMotionListener,
        MouseListener {

    private JPanel leftPanel = new JPanel(null);
    private JPanel rightPanel = new JPanel(null);
    JLabel dropLabel;

    public DragTest() {
        this.setLayout(new GridLayout(1, 2));

        leftPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        rightPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        this.add(leftPanel);
        this.add(rightPanel);
        leftPanel.addMouseListener(this);
        leftPanel.addMouseMotionListener(this);

        JTextArea area = new JTextArea();

        rightPanel.setLayout(new GridLayout(1, 1));
        rightPanel.add(area);

        dropLabel = new JLabel("drop");
        dropLabel.setTransferHandler(new TransferHandler("text"));

    }

    @Override
    public void mousePressed(MouseEvent e) {
        System.out.println("mousePressed");


        Dimension labelSize = dropLabel.getPreferredSize();
        dropLabel.setSize(labelSize);
        int x = e.getX() - labelSize.width / 2;
        int y = e.getY() - labelSize.height / 2;
        dropLabel.setLocation(x, y);
        leftPanel.add(dropLabel);


        dropLabel.getTransferHandler().exportAsDrag(dropLabel, e,
                TransferHandler.COPY);

        repaint();

    }

    @Override
    public void mouseDragged(MouseEvent me) {
        System.out.println("mouseDragged");
    }

    @Override
    public void mouseMoved(MouseEvent e) {

    }

    @Override
    public void mouseClicked(MouseEvent e) {
        System.out.println("mouseClicked");
    }

    @Override
    public void mouseReleased(MouseEvent e) {

        System.out.println("mouseReleased");

    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

    public static void main(String[] args) {

        DragTest frame = new DragTest();
        frame.setVisible(true);
        frame.setSize(600, 400);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

Answer 1

你真的需要释放鼠标来触发还是什么？我认为这应该运作良好:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.TransferHandler;

public class DragTest extends JFrame implements MouseMotionListener,
        MouseListener {

    private JPanel leftPanel = new JPanel(null);
    private JPanel rightPanel = new JPanel(null);
    JLabel dropLabel;

    public DragTest() {
        this.setLayout(new GridLayout(1, 2));

        leftPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        rightPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        this.add(leftPanel);
        this.add(rightPanel);
        leftPanel.addMouseListener(this);
        leftPanel.addMouseMotionListener(this);

        JTextArea area = new JTextArea();

        rightPanel.setLayout(new GridLayout(1, 1));
        rightPanel.add(area);

        dropLabel = new JLabel("drop");
        dropLabel.setTransferHandler(new TransferHandler("text"));

    }
    @Override
    public void mousePressed(MouseEvent e) {
        System.out.println("mousePressed");
        Dimension labelSize = dropLabel.getPreferredSize();
        dropLabel.setSize(labelSize);
        int x = e.getX() - labelSize.width / 2;
        int y = e.getY() - labelSize.height / 2;
        dropLabel.setLocation(x, y);
        leftPanel.add(dropLabel);



        repaint();

    }

    @Override
    public void mouseDragged(MouseEvent me) {
        System.out.println("mouseDragged");
            dropLabel.getTransferHandler().exportAsDrag(dropLabel, me,
                    TransferHandler.COPY);
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        System.out.println("mouseClicked");
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        System.out.println("mouseReleased");

    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

    public static void main(String[] args) {

        DragTest frame = new DragTest();
        frame.setVisible(true);
        frame.setSize(600, 400);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

我刚刚将启动拖动事件的调用移至 mouseDragged 调用中，这样，如果您只需单击鼠标，则一切都会正常调用。但是，如果您拖动鼠标，它将触发拖放调用，这仍然会阻止其他调用，但前提是您拖动鼠标。如果你只是点击，一切都会正常触发。