java - BoxLayout.X_AXIS 中 JPanel 上的 EmptyBorders

Question

我有一个自定义的 JPanel，重写了 paintComponent 方法来绘制图像。

我想在一个容器中垂直居中插入几个自定义面板。为此，我使用 BoxLayout.X_AXIS 创建了一个 jpanel 作为布局管理器。

效果很好，显示了我想要的内容，但我想在自定义面板之间添加边距。

EmptyMargins 只是被忽略了，棘手的部分是我不能(或不想...)在它们之间添加支柱或框，因为我需要从一个包含所有组件的循环中获取每个自定义面板容器并将它们转换到 CustomPanel 中。

看到问题了吗？如果我在面板之间添加支柱，将会出现强制转换异常并且 EmptyBorders 无法正常工作...欢迎提出任何想法!

注意:我愿意接受其他布局管理器的建议! ;-)

代码如下:

public class StackExemple {

public StackExemple() {

    JFrame frame = new JFrame();
    frame.setPreferredSize(new Dimension(600, 300));

    JPanel container = new JPanel();
    container.setPreferredSize(new Dimension(600, 300));
    container.setLayout(new BoxLayout(container, BoxLayout.X_AXIS));

    CustomPanel customPanel1 = new CustomPanel();
    CustomPanel customPanel2 = new CustomPanel();
    CustomPanel customPanel3 = new CustomPanel();

    container.add(customPanel1);
    container.add(customPanel2);
    container.add(customPanel3);

    frame.getContentPane().add(container);
    frame.pack();
    frame.setVisible(true);

    //Loop which takes the custompanels
    for(Component comp : container.getComponents()) {
        CustomPanel panel = (CustomPanel)comp;
        //DO SOMETHING

        System.out.println("Hello World");
    }
}

private class CustomPanel extends JPanel{

    private BufferedImage image;

    public CustomPanel() {
        setPreferredSize(new Dimension(100, 100));
        setMinimumSize(getPreferredSize());
        setMaximumSize(getPreferredSize());
        setBorder(BorderFactory.createEmptyBorder(0,50,0,0));
        setBackground(Color.RED);

//      try {
//          image = ImageIO.read(ClassLoader.getSystemClassLoader().getResource("Ressources/img.png"));
//      } catch (IOException ex) {
//           System.out.println("Ooops... ");
//      }
    }

    @Override
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
//      int x = (this.getWidth() - image.getWidth()) / 2;
//      int y = (this.getHeight() - image.getHeight()) / 2;
//      g.drawImage(image, x, y, null);
    }
}
}

Answer 1

• Borders are correct, have to getBackground from parent for LineBorders

• 覆盖 Min / Max / PreferredSize for BoxLayout

• BoxLayout 默认接受 Min/Max/PreferredSize

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.image.BufferedImage;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class StackExemple {

    public StackExemple() {
        JFrame frame = new JFrame();
        JPanel container = new JPanel();
        container.setLayout(new BoxLayout(container, BoxLayout.X_AXIS));
        CustomPanel customPanel1 = new CustomPanel(Color.blue);
        CustomPanel customPanel2 = new CustomPanel(Color.red);
        CustomPanel customPanel3 = new CustomPanel(Color.green);
        container.add(customPanel1);
        container.add(customPanel2);
        container.add(customPanel3);
        frame.getContentPane().add(container);
        frame.pack();
        frame.setVisible(true);
        for (Component comp : container.getComponents()) {
            CustomPanel panel = (CustomPanel) comp;
            System.out.println("Hello World");
        }
    }

    private class CustomPanel extends JPanel {

        private BufferedImage image;

        @Override
        public Dimension getMinimumSize() {
            return new Dimension(100, 80);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 160);
        }

        @Override
        public Dimension getMaximumSize() {
            return new Dimension(400, 320);
        }

        public CustomPanel(Color c) {
            setBorder(BorderFactory.createCompoundBorder(
                    BorderFactory.createEmptyBorder(10, 10, 10, 10), 
                    BorderFactory.createLineBorder(Color.black, 1)));
            //setBorder(BorderFactory.createCompoundBorder(
            //BorderFactory.createLineBorder(Color.black, 1), 
            //BorderFactory.createEmptyBorder(10, 10, 10, 10)));
            setBackground(c);
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                StackExemple stackExemple = new StackExemple();
            }
        });
    }
}