java - 如何获取对 JFrame 内发生 MouseEvent 的元素的引用

Question

我编写了 mouseinputlistener 方法的实现

public void mouseDragged(MouseEvent e){
    Pion c = (Pion)e.getSource(); 
    c.setBounds(e.getX() + c.getX(), e.getY() + c.getY(), 30, 30);

}

我在类中实现了它，它是JFrame的扩展，它包含一个具有不同组件的gridLayout:JPanel并且一些面板包含JButtons

我需要的是一种方法，它可以为我提供对发生事件的组件的引用，无论它是 JPanel 还是 JButton。

我尝试使用 e.getSource，但显然它不起作用，代码可以编译，但每次我在组件上拖动鼠标时，都会收到一个异常，提示“Plateau(即扩展 JFrame 的当前类)无法转换为 Pion(即扩展 JButton 的类)”

我尝试为扩展组件(Pion 等)的每个类实现 MouseInputListener，但我需要在 JFrame 规模上执行操作，而这不允许这样做。

这是我得到的异常:

java.lang.ClassCastException: PlateauColorLine cannot be cast to javax.swing.JPanel
at PlateauColorLine.mouseDragged(PlateauColorLine.java:299)
at java.awt.Component.processMouseMotionEvent(Component.java:6564)
at java.awt.Component.processEvent(Component.java:6285)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Window.processEvent(Window.java:2022)
at java.awt.Component.dispatchEventImpl(Component.java:4872)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4698)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:747)
at java.awt.EventQueue.access$300(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:706)
at java.awt.EventQueue$3.run(EventQueue.java:704)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:77)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:720)
at java.awt.EventQueue$4.run(EventQueue.java:718)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:77)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:717)
at org.GNOME.Accessibility.AtkWrapper$5.dispatchEvent(AtkWrapper.java:697)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

`

Answer 1

希望这会有所帮助

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

class Pion extends JButton
{
    public Pion (String title)
    {
        super(title);
        addMouseListener(new MouseListnerAdapter());
    }
}

class MouseListnerAdapter extends MouseAdapter
{
    @Override
    public void mousePressed(MouseEvent e) {
        Object o = e.getSource();

        if(o instanceof JButton)
        {
            JButton b = (JButton) o;
            b.setBounds(e.getX() + b.getX(), e.getY() + b.getY(), 30, 30);
        }
    }
};


public class Test extends JFrame {
    public Test() 
    {
        super("Test");        
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLayout(new GridLayout(2,1));


        JPanel p1 = new JPanel();
        Pion pb1 = new Pion("button1");
        p1.add(pb1);
        add(p1);

        JPanel p2 = new JPanel();
        Pion pb2 = new Pion("button2");
        p2.add(pb2);
        add(p2);        

        pack();
        setSize(240, 240);
        setLocationByPlatform(true);
        setVisible(true);
        addMouseListener(new MouseListnerAdapter());

    }

    public static void main(String[] args)throws Exception 
    {
        new Test();
    }
}