自定义Java鼠标监听器？

Question

首先,我作为网站程序员来到Java.在JavaScript中,您只需调用addEventListener函数即可添加mousemove,mouseover或click事件.根据我对Java的有限经验,您不能只从任何对象实现MouseListener接口.

基本上,到目前为止我所拥有的是一个JPanel,它绘制了一些具有x/y/width/height值的形状(带有绘制方法的CustomShape对象).我想在形状对象中添加一些类型的鼠标监听器,这样我就可以触发形状的移动/滚动/点击事件.只是将ButtonListener接口实现到CustomShape对象不起作用(我认为这是显而易见的原因).我已经查找了如何设计自定义事件监听器,但似乎并不是可以创建自定义鼠标监听器.

我最终使用鼠标监听器添加到JPanel,然后循环遍历所有形状对象.如果形状对象附加了"侦听器",并且鼠标坐标已验证鼠标事件已发生,则会触发该方法.最初,它很好,但随着应用程序越来越发达,它开始变得非常混乱.另外,如果不复制一堆代码,我将永远无法将形状对象/接口复制到另一个应用程序.

作为一个简单的说明:(实际代码非常大)

Interface CustomShape{
    int width, height, x, y;
    void paint(Graphics g);
}

public class StarShape implements CustomShape{
    int width, height, x, y;
    public StarShape(){
        width = 100;
        height = 100;
        x = 50;
        y = 50;
    }
    void paint(Graphics g){
        g.setColor(Color.black);
        g.draw(new Rectangle(x,y,width,height));
    }
}

public class Main extends JPanel{
    StarShape check = new StarShape();
    public Main(){  }
    @Override
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        check.paint(g);
    }
}

所以,我想知道是否有一种干净的方式来实现某种类型的鼠标监听器的"手绘"形状.

Answer 1

为了能够接收事件,您的"Shape"对象应该扩展java.awt.Component(或javax.swing.JComponent).然后,您可以将它们作为子项添加到JPanel,它们将接收事件,您可以直接向它们添加侦听器.

你正在做的事情,你必须在JPanel中手动跟踪形状的位置.您将鼠标侦听器添加到面板本身,并根据您获得的事件的x/y坐标,在形状上调用一些方法来处理事件.这几乎是重新实现基本AWT/Swing类将为您做什么.

Answer 2

我做你想做的事情的方法。编译、运行、读取:-)

（注意：您可以将下面的每一行代码复制到一个文件中Example01.java。编译并运行它。）

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

public class Example01 {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame jf = new JFrame();
                MainPanel mainPanel = new MainPanel();
                jf.add(mainPanel);
                jf.setSize(640, 480);
                jf.setLocationRelativeTo(null);
                jf.setVisible(true);
            }
        });
    }
}

class MainPanel extends JPanel {
    StarShape check1 = new StarShape();
    StarShape check2 = new StarShape();

    public MainPanel() {
        check1.setName("check1");
        check2.setName("check2");
        check1.addMouseListener(new MyMouseListener(check1));
        check2.addMouseListener(new MyMouseListener(check2));
        this.add(check1);
        this.add(check2);
    }
}

class StarShape extends JComponent {
    public StarShape() {
        this.setPreferredSize(new Dimension(100, 100));
    }

    @Override
    protected void paintComponent(Graphics g) {
        g.setColor(Color.black);
        Graphics2D g2d = (Graphics2D) g;
        int x = 0;
        int y = 0;
        int width = this.getWidth() - 1;
        int height = this.getHeight() - 1;
        g2d.draw(new Rectangle(x, y, width, height));
    }
}

class MyMouseListener implements MouseListener {
    private final JComponent component;

    public MyMouseListener(JComponent component) {
        this.component = component;
    }

    public void mouseClicked(MouseEvent e) {
        System.out.println("mouseClicked: " + component.getName());
    }

    public void mouseEntered(MouseEvent e) {
        System.out.println("mouseEntered: " + component.getName());
        Dimension preferredSize = component.getPreferredSize();
        preferredSize.height += 20;
        preferredSize.width += 20;
        component.setPreferredSize(preferredSize);
        component.invalidate();
        SwingUtilities.getWindowAncestor(component).validate();
    }

    public void mouseExited(MouseEvent e) {
        System.out.println("mouseExited: " + component.getName());
        Dimension preferredSize = component.getPreferredSize();
        preferredSize.height -= 20;
        preferredSize.width -= 20;
        component.setPreferredSize(preferredSize);
        component.invalidate();
        SwingUtilities.getWindowAncestor(component).validate();
    }

    public void mousePressed(MouseEvent e) {
        System.out.println("mousePressed: " + component.getName());
    }

    public void mouseReleased(MouseEvent e) {
        System.out.println("mouseReleased: " + component.getName());
    }
}