使jtoolbar透明

Question

我有一个背景jPanel，我想在它上面添加一个JToolbar。
我的问题是当我添加JToolbar时，它的默认背景很麻烦，我将它设置为不透明而不起作用。
我想删除它的默认背景并使其透明。
我看了下面的文章，但没有帮助：
JToolbar background image
这里是我的代码：

import java.awt.Color; 
import java.awt.Graphics; 
import java.awt.Image; 

import javax.swing.Action; 
import javax.swing.Icon; 
import javax.swing.ImageIcon; 
import javax.swing.JButton; 
import javax.swing.JToolBar; 

public class Toolbar extends JToolBar { 

    private JButton manage; 
    private JButton add; 
    private JButton search; 
    private JButton exit; 

    public Toolbar() { 
     super(); 

     manage = new JButton(); 
     add = new JButton(); 
     search = new JButton(); 
     exit = new JButton(); 

     ImageIcon icon = new ImageIcon("pics/Add-01.png"); 
     Image img = icon.getImage(); 
     Image newImage = img.getScaledInstance(80, 80, Image.SCALE_SMOOTH); 
     add.setIcon(new ImageIcon(newImage)); 

     setOpaque(false); 

     setBackground(Color.RED); 

     add(add); 
     add(search); 
     add(manage); 
     add(exit); 

    } 

} 

谢谢您的支持。
不工作代码：

public class Toolbar extends JToolBar { 

    public Toolbar() { 
     setBackground(Color.RED); 
     setOpaque(false); 
     add(new JButton("add")); 
    } 

    protected void addImpl(Component comp, Object constraints, int index) { 
     super.addImpl(comp, constraints, index); 
     if (comp instanceof JButton) { 
      ((JButton) comp).setContentAreaFilled(false); 
     } 
    } 

} 

Answer 1

基本上，按键仍然是 “填充” 他们的背景。您可以指示他们不要通过JButton#setContentAreaFilled

此示例将JToolBar红色的背景色画自己的内容（背景），所以你可以看到按钮现在是透明的。为了使工具栏透明，只是在构造

public class CustomToolBar extends JToolBar { 

    public CustomToolBar() { 
     setBackground(Color.RED); 
    } 

    protected void addImpl(Component comp, Object constraints, int index) { 
     super.addImpl(comp, constraints, index); 
     if (comp instanceof JButton) { 
      ((JButton) comp).setContentAreaFilled(false); 
     } 
    } 

} 

扩展例如添加setOpaque(false) ....

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Component; 
import java.awt.Dimension; 
import java.awt.EventQueue; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.IOException; 
import javax.imageio.ImageIO; 
import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JToolBar; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 
import javax.swing.border.LineBorder; 

public class Test { 

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

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

       JButton manage = new JButton("Manage"); 
       JButton add = new JButton("Add"); 
       JButton search = new JButton("Search"); 
       JButton exit = new JButton("Exit"); 
       CustomToolBar tb = new CustomToolBar(); 
       tb.add(manage); 
       tb.add(add); 
       tb.add(search); 
       tb.add(exit); 

       JFrame frame = new JFrame("Testing"); 
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       frame.setContentPane(new TestPane()); 
       frame.add(tb, BorderLayout.NORTH); 
       frame.pack(); 
       frame.setLocationRelativeTo(null); 
       frame.setVisible(true); 
      } 
     }); 
    } 

    public class TestPane extends JPanel { 

     private BufferedImage bgImg; 

     public TestPane() { 
      setLayout(new BorderLayout()); 
      try { 
       bgImg = ImageIO.read(new File("...")); 
      } catch (IOException ex) { 
       ex.printStackTrace(); 
      } 
     } 

     @Override 
     public Dimension getPreferredSize() { 
      return bgImg == null ? new Dimension(200, 200) : new Dimension(bgImg.getWidth(), bgImg.getHeight()); 
     } 

     @Override 
     protected void paintComponent(Graphics g) { 
      super.paintComponent(g); 
      if (bgImg != null) { 
       Graphics2D g2d = (Graphics2D) g.create(); 
       int x = (getWidth() - bgImg.getWidth())/2; 
       int y = (getHeight() - bgImg.getHeight())/2; 
       g2d.drawImage(bgImg, x, y, this); 
       g2d.dispose(); 
      } 
     } 

    } 

    public class CustomToolBar extends JToolBar { 

     public CustomToolBar() { 
      setBorder(new LineBorder(Color.BLACK, 2)); 
      setOpaque(false); 
     } 

     @Override 
     protected void addImpl(Component comp, Object constraints, int index) { 
      super.addImpl(comp, constraints, index); 
      if (comp instanceof JButton) { 
       ((JButton) comp).setContentAreaFilled(false); 
      } 
     } 

    } 

}