鼠标悬停在java中删除圆形JButton的透明背景

如何解决鼠标悬停在java中删除圆形JButton的透明背景

一旦我将鼠标悬停在任何圆形按钮上，它后面就会出现一个方形背景，并且再也不会消失。该按钮仍然可点击，而方形背景则不可点击。我没有实现任何 MouseEvents 所以我不知道为什么会出现背景

左：被点击后，中心：鼠标悬停后，右：原始状态

代码示例

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

public class GUI implements ActionListener {
    private JLabel textLabel;
    private JButton buttonL,buttonConfirm,buttonR;
    
    public GUI() {
        JPanel maindisplay = new JPanel();
        maindisplay.setBackground(new Color(172,181,176));
        maindisplay.setPreferredSize(new Dimension(150,160));
        maindisplay.setLayout(new BorderLayout());
        textLabel = new JLabel("1");
        textLabel.setHorizontalAlignment(SwingConstants.CENTER);
        maindisplay.add(textLabel,BorderLayout.CENTER);
        
        JPanel container = new JPanel();
        container.setLayout(new GridBagLayout());
        GridBagConstraints gc = new GridBagConstraints();
        gc.gridwidth = GridBagConstraints.REMAINDER;
        gc.insets = new Insets(75,0);
        container.add(maindisplay,gc);
        
        Dimension buttonDimension = new Dimension(18,18);
        Color buttonColor = new Color(242,240,241);
        buttonL = new RoundButton();
        buttonL.setBackground(buttonColor);
        buttonL.setPreferredSize(buttonDimension);
        buttonL.addActionListener(this);
        gc.gridwidth = GridBagConstraints.RELATIVE;
        gc.insets = new Insets(10,20,0);
        container.add(buttonL,gc);
        
        buttonConfirm = new RoundButton();
        buttonConfirm.setBackground(buttonColor);
        buttonConfirm.setPreferredSize(buttonDimension);
        buttonConfirm.addActionListener(this);
        gc.insets = new Insets(40,-35,0);
        container.add(buttonConfirm,gc);
        
        buttonR = new RoundButton();
        buttonR.setBackground(buttonColor);
        buttonR.setPreferredSize(buttonDimension);
        buttonR.addActionListener(this);
        gc.insets = new Insets(10,-50,0);
        container.add(buttonR,gc);
        
        JFrame frame = new JFrame();
        frame.add(container);
        frame.pack();
        frame.setLocationRelativeto(null);
        frame.setVisible(true);
    }
    
    @Override
    public void actionPerformed(ActionEvent e) {
        if(e.getSource() == buttonL) {
            textLabel.setText("L");;
        } else if(e.getSource() == buttonConfirm) {
            textLabel.setText("");
        } else if(e.getSource() == buttonR) {
            textLabel.setText("R");
        }
    }
    
    public static void main(String[] args) {        
            new GUI();
    }
}

圆形 JButton

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Shape;
import java.awt.geom.Ellipse2D;
import javax.swing.JButton;

public class RoundButton extends JButton {
    Shape shape;
    
    @Override
    protected void paintComponent(Graphics g) {
        g.setColor(getBackground());
        g.filloval(0,getSize().width - 1,getSize().height - 1);
    }

    @Override
    protected void paintBorder(Graphics g) {
        g.setColor(Color.darkGray);
        g.drawoval(0,getSize().height - 1);
    }

    @Override
    public boolean contains(int x,int y) {
        if (shape == null || !shape.getBounds().equals(getBounds())) {
            shape = new Ellipse2D.Float(0,getWidth(),getHeight());
        }
        return shape.contains(x,y);
    }
}

解决方法

进行自定义绘制时，基本代码应为：

public void paintComponent(Graphics g)
{
    super.paintComponent(g);

    // add custom painting here
}

这将确保清除背景，因此没有绘画伪影。

但是，在您的情况下，您希望在绘制按钮之前绘制父面板的背景，因此您需要使用：

button.setOpaque(false);

此外，当您单击按钮时，矩形仍会出现，表示按钮处于按下状态。要删除这幅画，您需要使用：

button.setContentAreaFilled( false );

查看：Change JButton focus area 以了解圆形按钮的另一种实现方式。