Question

java中swing界面上怎么给jpanel上添加背景图片

Answer 1

      //重写JPanel的这个方法就可以了
       @Override  
    public void paintComponent(Graphics gs) {  
        Graphics2D g = (Graphics2D) gs;  
        super.paintComponent(g);  
        //画背景图片  
        Image image = Toolkit.getDefaultToolkit().getImage(getClass().getResource(imgPath));  
        g.drawImage(image, 0, 0,width,height, this);  
    }

一个完整的代码:

package test;

import java.awt.Graphics;
import java.awt.Image;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;

//为窗口添加背景图片
public class JFrameBackground {

	private JFrame frame = new JFrame("带背景图片的JFrame");
	private JPanel imagePanel;
	private ImageIcon backgroundimg;

	public JFrameBackground() {

		imagePanel = new JPanel() {
			@Override
			protected void paintComponent(Graphics g) {
				super.paintComponent(g);
				URL location = this.getClass().getResource("grapes.gif");
				backgroundimg = new ImageIcon(location);
				Image img = backgroundimg.getImage();
				g.drawImage(img, 0, 0, backgroundimg.getIconWidth(),
						backgroundimg.getIconHeight(),
						backgroundimg.getImageObserver());
				frame.setSize(backgroundimg.getIconWidth(),
						backgroundimg.getIconHeight());
			}

		};

		frame.add(imagePanel);
		frame.setVisible(true);
		frame.pack();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

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

这是运行的一个截图:

参考网址: 

http://www.linuxidc.com/Linux/2011-08/41689.htm 两种设置背景的方法

http://blog.csdn.net/one_and_only4711/article/details/6594770 动态改变背景大小

Answer 2

import javax.swing.JPanel;
import java.awt.Image;
import javax.swing.ImageIcon;
import java.awt.Graphics;
class GetPanel extends JPanel {
private static final long serialVersionUID = 1L;
int width = 0, hight = 0;
String imgpath = "";
public GetPanel(int width, int hight, String file) {
this.width = width;
this.hight = hight;
imgpath = file;
}
protected void paintComponent(Graphics g) {
ImageIcon icon = new ImageIcon(imgpath);
Image img = icon.getImage();
g.drawImage(img, 0, 0, width, hight, this);
}
}
GetPanel继承了JPanel，同时又加入了paintComponent（）方法。
JPanel jContentPane = new GetPanel(500,375,"login.png");
这样就可以给面板加上背景图片了

Answer 3

代码在附件，你参考下