Java 如何使JFrame透明/不透明，而不必设置为未装饰（true） 是否有一种方法可以将JFrame设置为透明，同时仍不影响按钮/文本 如果不是，如何在不使用.setUndercorated（true）的情况下使JFrame透明 这是一个完全不同的问题，但我如何添加渐变作为背景色，而不是将其设置为一种纯色 单击以查看程序运行时JFrame的外观

以下是透明JFrame的源代码：

public class Example extends JFrame {
    public Example() {
        super("TranslucentWindowDemo");
        setLayout(new GridBagLayout());
        setSize(500,300);
        setLocationRelativeTo(null);
        setUndecorated(true);
        getContentPane().setBackground(Color.blue);

        JButton Close = new JButton("Close");
        add(Close);
        ActionListener al;
        al = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                System.exit(0);
            }
        };
        Close.addActionListener (al);
    }

    private void initComponents() {
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
        pack();
    }                     

    public static void main(String args[]) {
       GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
       GraphicsDevice gd = ge.getDefaultScreenDevice();

        if (!gd.isWindowTranslucencySupported(TRANSLUCENT)) {
            System.err.println("Translucency is not supported");
            System.exit(0); 
        }
        try {
            for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {

            java.util.logging.Logger.getLogger(Example.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                Example e = new Example();
                e.setOpacity(0.55f);
                e.setVisible(true);
            }
        });
    }         
}

---

对于不透明度，您可以尝试

Pane.setOpaque（false）
对于内容，您应该更改为
setBackground（新颜色（0,0,0,0））

您可以阅读更多内容
1：是的，制作一个透明窗口，然后在其上添加一个透明JPanel，覆盖它的paintComponent并用透明颜色填充它；2：没有；3：见答案一：
public class Example extends JFrame {
    public Example() {
        super("TranslucentWindowDemo");
        setLayout(new GridBagLayout());
        setSize(500,300);
        setLocationRelativeTo(null);
        setUndecorated(true);
        getContentPane().setBackground(Color.blue);

        JButton Close = new JButton("Close");
        add(Close);
        ActionListener al;
        al = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                System.exit(0);
            }
        };
        Close.addActionListener (al);
    }

    private void initComponents() {
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
        pack();
    }                     

    public static void main(String args[]) {
       GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
       GraphicsDevice gd = ge.getDefaultScreenDevice();

        if (!gd.isWindowTranslucencySupported(TRANSLUCENT)) {
            System.err.println("Translucency is not supported");
            System.exit(0); 
        }
        try {
            for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {

            java.util.logging.Logger.getLogger(Example.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                Example e = new Example();
                e.setOpacity(0.55f);
                e.setVisible(true);
            }
        });
    }         
}