java - BorderLayout 显示不正确

Question

我想要一个 JFrame，在左侧和右侧有一个黑色边框，宽度为 withfOfJFrame/10。

现在，我的尝试看起来像这样:

JFrame f = new JFrame();
f.setSize(800, 600);
f.setLayout(new BorderLayout());

JPanel leftBorder = new JPanel();
JPanel rightBorder = new JPanel();
leftBorder.setBackground(Color.black);
rightBorder.setBackground(Color.black);
leftBorder.setSize(f.getWidth()/10, f.getHeight());
rightBorder.setSize(f.getWidth()/10, f.getHeight());
JPanel center = new JPanel();
center.setBackground(Color.red);

f.add(leftBorder, BorderLayout.WEST);
f.add(center, BorderLayout.CENTER);
f.add(rightBorder, BorderLayout.EAST);    
f.setVisible(true);

这会在左侧和右侧添加一个黑色边框，但该边框具有固定大小并且在调整窗口大小时不会重新计算。大小甚至不到 800 的 1/10(JFrame 的起始宽度)。

我做错了什么？还是有更好的方法来做到这一点？

Answer 1

您可以使用 GridBagLayout 获得所需的结果和适当的权重:

public class Snippet {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                JFrame f = new JFrame();
                f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

                JPanel leftBorder = new JPanel();
                JPanel rightBorder = new JPanel();
                leftBorder.setBackground(Color.black);
                rightBorder.setBackground(Color.black);

                JPanel center = new JPanel();
                center.setBackground(Color.red);

                f.setLayout(new GridBagLayout());

                GridBagConstraints gbc = new GridBagConstraints();
                gbc.fill = GridBagConstraints.BOTH;
                gbc.weighty = 1.0;
                gbc.gridy = 0;
                gbc.gridwidth = 1;
                gbc.gridheight = 1;

                gbc.gridx = 0;
                gbc.weightx = 0.1;
                f.add(leftBorder, gbc);

                gbc.gridx = 1;
                gbc.weightx = 0.8;
                f.add(center, gbc);

                gbc.gridx = 2;
                gbc.weightx = 0.1;
                f.add(rightBorder, gbc);

                f.pack();
                f.setVisible(true);
            }
        });
    }
}