在GridBagLayout中设置任意宽度

Question

我试图制作一个键盘布局，其中可以指定按钮的宽度。因此，我尝试了GridBagLayout但没有成功。 为了说明我的问题，我做了一个简单的例子，在那里我有望获得这个（Button2的，将Button4，Button5，Button6）：

而是我得到的将Button4和双倍宽度的Button6。

的代码是：

package views; 

import java.awt.BorderLayout; 
import java.awt.EventQueue; 
import java.awt.GridBagConstraints; 
import java.awt.GridBagLayout; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 

public class TestLayout extends JFrame { 

    public static void main(String[] args) { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       new TestLayout().setVisible(true); 
      } 
     }); 
    } 

    public TestLayout() { 
     JButton btn; 
     setBounds(0, 0, 444, 111); 
     setLayout(new GridBagLayout()); 
     GridBagConstraints gbc = new GridBagConstraints(); 
     gbc.fill = GridBagConstraints.BOTH; 

     gbc.gridy = 1;//ROW 1 
     btn = new JButton("Button 1");gbc.gridx = 0;gbc.gridwidth = 1;add(btn, gbc); 
     btn = new JButton("Button 2");gbc.gridx = 1;gbc.gridwidth = 2;add(btn, gbc); 
     btn = new JButton("Button 3");gbc.gridx = 3;gbc.gridwidth = 1;add(btn, gbc); 
     btn = new JButton("Button 4");gbc.gridx = 4;gbc.gridwidth = 2;add(btn, gbc); 

     gbc.gridy = 2;//ROW 2 
     btn = new JButton("Button 5");gbc.gridx = 0;gbc.gridwidth = 2;add(btn, gbc); 
     btn = new JButton("Button 6");gbc.gridx = 2;gbc.gridwidth = 2;add(btn, gbc); 
     btn = new JButton("Button 7");gbc.gridx = 4;gbc.gridwidth = 1;add(btn, gbc); 
     btn = new JButton("Button 8");gbc.gridx = 5;gbc.gridwidth = 1;add(btn, gbc); 
    } 
} 

而且，我的目标是定义键盘这样的事情，与排之间没有相关性，这是我不能用这个布局管理器来实现的：

Answer 1

我把这件事交给了Why does this GridBagLayout not appear as planned? & camickr用一个虚拟的组件行来解决它，每个组件都有1 gridwidth宽。

这些2个图像显示：

1. 在底部，代码的 '极简' 版本使用1px的高透明图像。
2. 在顶部，更明显的版本使用了5像素高的纯黑色图像。

---

import java.awt.*; 
import java.awt.image.BufferedImage; 
import javax.swing.*; 
import javax.swing.border.*; 

public class KeyBoardLayout { 

    private JComponent ui = null; 

    KeyBoardLayout(boolean lowImpact) { 
     initUI(lowImpact); 
    } 

    public void initUI(boolean lowImpact) { 
     if (ui != null) { 
      return; 
     } 

     ui = new JPanel(new GridBagLayout()); 
     ui.setBorder(new EmptyBorder(4, 4, 4, 4)); 
     GridBagConstraints gbc = new GridBagConstraints(); 
     gbc.weightx = .5; 
     gbc.weighty = .5; 
     gbc.fill = GridBagConstraints.BOTH; 

     /* This code adds a dummy (invisible) row of components, 1 per 
     single gridwidth column. It has the effect of forcing the GBL width 
     to the size we would expect, proportional to each gridwidth assigned. 
     The problem with this (simple) approach is that the perfect 
     width will change according to PLAF and the content/preferred 
     size of the visible components. */ 
     // TODO! improve on use of 'magic numbers' 
     int w = 30; // adjust width per requirement 
     int h = lowImpact ? 1 : 5; // 1 for small height/border, 5 for large 
     // TYPE_INT_RGB for black 
     // TYPE_INT_ARGB for invisible 
     int t = lowImpact ? 
       BufferedImage.TYPE_INT_ARGB : 
       BufferedImage.TYPE_INT_RGB; 
     // an icon for the dummy row 
     ImageIcon ii = new ImageIcon(new BufferedImage(w, h, t)); 
     ui.setBorder(new CompoundBorder(
       ui.getBorder(), new EmptyBorder(0, 0, h, 0))); 
     // put a 'padding cell' in each column of the top row 
     // to force the layout to respect each individual column 
     for (int i = 0; i < 22; i++) { 
      gbc.gridx = i; 
      gbc.gridy = 4; 
      ui.add(new JLabel(ii)); 
     } 

     gbc.gridx = 0; 
     gbc.gridy = 1; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("1,1 (3)"), gbc); 

     gbc.gridx = 3; 
     gbc.gridwidth = 2; 
     ui.add(new JButton("2,1 (2)"), gbc); 

     gbc.gridx = 5; 
     ui.add(new JButton("3,1 (2)"), gbc); 

     gbc.gridx = 7; 
     ui.add(new JButton("4,1 (2)"), gbc); 

     gbc.gridx = 9; 
     ui.add(new JButton("5,1 (2)"), gbc); 

     gbc.gridx = 11; 
     ui.add(new JButton("6,1 (2)"), gbc); 

     gbc.gridx = 13; 
     ui.add(new JButton("7,1 (2)"), gbc); 

     gbc.gridx = 15; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("8,1 (3)"), gbc); 

     gbc.gridx = 18; 
     gbc.gridwidth = 4; 
     ui.add(new JButton("9,1 (4)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 2; 
     ui.add(new JButton("1,2 (4)"), gbc); 

     gbc.gridx = 4; 
     gbc.gridwidth = 2; 
     ui.add(new JButton("2,2 (2)"), gbc); 

     gbc.gridx = 6; 
     ui.add(new JButton("3,2 (2)"), gbc); 

     gbc.gridx = 8; 
     ui.add(new JButton("4,2 (2)"), gbc); 

     gbc.gridx = 10; 
     ui.add(new JButton("5,2 (2)"), gbc); 

     gbc.gridx = 12; 
     ui.add(new JButton("6,2 (2)"), gbc); 

     gbc.gridx = 14; 
     ui.add(new JButton("7,2 (2)"), gbc); 

     gbc.gridx = 16; 
     ui.add(new JButton("8,2 (2)"), gbc); 

     gbc.gridx = 18; 
     gbc.gridwidth = 4; 
     ui.add(new JButton("9,2 (4)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 3; 
     gbc.gridwidth = 5; 
     ui.add(new JButton("1,3 (5)"), gbc); 

     gbc.gridx = 5; 
     gbc.gridwidth = 2; 
     ui.add(new JButton("2,3 (2)"), gbc); 

     gbc.gridx = 7; 
     ui.add(new JButton("3,3 (2)"), gbc); 

     gbc.gridx = 9; 
     ui.add(new JButton("4,3 (2)"), gbc); 

     gbc.gridx = 11; 
     ui.add(new JButton("5,3 (2)"), gbc); 

     gbc.gridx = 13; 
     ui.add(new JButton("6,3 (2)"), gbc); 

     gbc.gridx = 15; 
     ui.add(new JButton("7,3 (2)"), gbc); 

     gbc.gridx = 17; 
     ui.add(new JButton("8,3 (2)"), gbc); 

     gbc.gridx = 19; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("9,3 (3)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 4; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("1,4 (3)"), gbc); 

     gbc.gridx = 3; 
     ui.add(new JButton("2,4 (3)"), gbc); 

     gbc.gridx = 6; 
     gbc.gridwidth = 10; 
     ui.add(new JButton("3,4 (10)"), gbc); 

     gbc.gridx = 16; 
     gbc.gridwidth = 3; 
     ui.add(new JButton("4,4 (3)"), gbc); 

     gbc.gridx = 19; 
     ui.add(new JButton("5,4 (3)"), gbc); 

     gbc.gridx = 0; 
     gbc.gridy = 4; 
     gbc.gridwidth = 1; 
    } 

    public JComponent getUI() { 
     return ui; 
    } 

    public static void main(String[] args) { 
     Runnable r = new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(
          UIManager.getSystemLookAndFeelClassName()); 
       } catch (Exception useDefault) { 
       } 
       for (int ii = 0; ii < 2; ii++) { 
        KeyBoardLayout o = new KeyBoardLayout(ii==0); 

        JFrame f = new JFrame("Keyboard Layout"); 
        f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 
        f.setLocationByPlatform(true); 

        f.setContentPane(o.getUI()); 
        f.pack(); 
        f.setMinimumSize(f.getSize()); 

        f.setVisible(true); 
       } 
      } 
     }; 
     SwingUtilities.invokeLater(r); 
    } 
}