java - 如何去除 JFrame 边框让图像触及边缘

Question

我有一个 friend 为我制作的程序做了一个背景，这样它看起来就不会那么平淡，我认为放置图像的最佳方式是制作一个 JLabel，用图像填充它，然后设置它到屏幕的大小。这工作正常，除了 JFrame 周围有一个小边框，我无法让 JLabel 接触框架的边缘。想法？我附上了一张照片。

public class ProgramDriver extends JFrame {

private JPanel contentPane;
private static CardLayout cardLayout;
private JTextField addGradeN;
private JTextField addGradeD;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                ProgramDriver frame = new ProgramDriver();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

//Global Variables 
...
    manager = new StateManager(gb);

    //JFrame Settings
    setTitle("Grade Book");
    setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    setBounds(100, 100, 656, 530);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    cardLayout = new CardLayout(0,0);
    contentPane.setLayout(cardLayout);
    setResizable(false);

    //Home Panel 
    final JPanel Home = new JPanel();
    contentPane.add(Home, "Home");
    Home.setLayout(null);

    JButton btnSeeGrades = new JButton("See Grades");
    ...

    //Grades Panel
    JPanel Grades = new JPanel();
    contentPane.add(Grades, "Grades");
    Grades.setLayout(null);'

Answer 1

问题不在于 JFrame，而在于您的代码。我们可以用余生来猜测问题所在，或者您可以发布一些示例代码。

现在由您决定，我们可以继续尝试对您进行错误的猜测，让我们所有人都感到沮丧，或者您可以帮助我们帮助您...

这是我做的两个例子。第一个使用 JLabel 作为 JPanel 的主要内容，其中放置了子组件。漂亮而简单。

第二个使用自定义 JPanel 将图像绘制到组件的背景上。然后我用它来替换框架内容 Pane 。这有点复杂，但它具有易于更新的额外好处(替换内容 Pane 不会影响程序的其余部分)

示例 1:JLabel 用作背景

public class TestBackground {

    public static final String BACKGROUND_PATH = "/Volumes/Macintosh HD2/Dropbox/MT015.jpg";

    public static void main(String[] args) {
        new TestBackground();
    }

    public TestBackground() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setLayout(new BorderLayout());
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new LabelPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);

            }
        });

    }

    protected class LabelPane extends JPanel {

        public LabelPane() {

            BufferedImage bg = null;
            try {
                bg = ImageIO.read(new File(BACKGROUND_PATH));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            JLabel label = new JLabel(new ImageIcon(bg));
            setLayout(new BorderLayout());

            add(label);

            label.setLayout(new GridBagLayout());

            JLabel lblMessage = new JLabel("Look at me!");
            lblMessage.setForeground(Color.WHITE);
            lblMessage.setFont(lblMessage.getFont().deriveFont(Font.BOLD, 48));

            label.add(lblMessage);

        }
    }
}

示例 2:图像用作背景，替换内容 Pane ...

public class TestBackground {
    public static final String BACKGROUND_PATH = "/Volumes/Macintosh HD2/Dropbox/MT015.jpg";

    public static void main(String[] args) {
        new TestBackground();
    }

    public TestBackground() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setLayout(new BorderLayout());
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setContentPane(new BackgroundPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    protected class BackgroundPane extends JPanel {

        private BufferedImage bg = null;

        public BackgroundPane() {
            try {
                bg = ImageIO.read(new File(BACKGROUND_PATH));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            setLayout(new GridBagLayout());

            JLabel lblMessage = new JLabel("Look at me!");
            lblMessage.setForeground(Color.WHITE);
            lblMessage.setFont(lblMessage.getFont().deriveFont(Font.BOLD, 48));

            add(lblMessage);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(1153, 823);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (bg != null) {
                g.drawImage(bg, 0, 0, this);
            }
        }
    }
}