java窗体透明没有效果 java窗体设置背景图片

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;

public class BackgroundImage extends JFrame
{
    JScrollPane scrollPane;
    ImageIcon icon;
    Image image;

    public BackgroundImage()
    {
        icon = new ImageIcon("bgpanel.jpg");

        JPanel panel = new JPanel()
        {
            protected void paintComponent(Graphics g)
            {
                // Dispaly image at at full size

                g.drawImage(icon.getImage(), 0, 0, null);

                // Scale image to size of component

//                Dimension d = getSize();

//                g.drawImage(icon.getImage(), 0, 0, d.width, d.height, null);


                // Fix the image position in the scroll pane

//                Point p = scrollPane.getViewport().getViewPosition();

//                g.drawImage(icon.getImage(), p.x, p.y, null);


                super.paintComponent(g);
            }
        };
        panel.setOpaque( false );
        panel.setPreferredSize( new Dimension(400, 400) );
        scrollPane = new JScrollPane( panel );
        getContentPane().add( scrollPane );

        JButton button = new JButton( "Hello" );
        panel.add( button );
    }

    public static void main(String [] args)
    {
        BackgroundImage frame = new BackgroundImage();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }
}

[img]http://photo1.bababian.com/20070315/0464FB8C817FC5E83DE36B723058CF40_500.jpg[/img]

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Image;

import javax.swing.GrayFilter;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class BackgroundSample {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Background Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    final ImageIcon imageIcon = new ImageIcon("parking6.gif");
    JTextArea textArea = new JTextArea() {
      Image image = imageIcon.getImage();

      Image grayImage = GrayFilter.createDisabledImage(image);
      {
        setOpaque(false);
      } // instance initializer


      public void paint(Graphics g) {
        g.drawImage(grayImage, 0, 0, this);
        super.paint(g);
      }
    };
    JScrollPane scrollPane = new JScrollPane(textArea);
    Container content = frame.getContentPane();
    content.add(scrollPane, BorderLayout.CENTER);
    frame.setSize(250, 250);
    frame.setVisible(true);
  }
}

[img]http://photo1.bababian.com/20070315/DB4EA5F1D06E95F0E436573D16124B5F_500.jpg[/img]

只不过好像不能很好显示色彩，不知道为什么？在研究中....

哦知道了，

Image grayImage = GrayFilter.createDisabledImage(image);

这里过滤了。

 // Image grayImage = GrayFilter.createDisabledImage(image);
      {
        setOpaque(false);
      } // instance initializer

      public void paint(Graphics g) {
        g.drawImage(imageIcon.getImage(), 0, 0, this);
        super.paint(g);
      }
    };

修改成这样就可以显示全彩：

[img]http://photo1.bababian.com/20070315/918947144F7B2CE1F3361F668BED5ECA_500.jpg[/img]