java_载入图片的几种常用方法

载入图片的几种常用方法 /** * <p>Title: PaintPanel</p> * <p>Description:此程序演示如何载入图片,并让其作为panel的背景</p> * <p>Copyright: Copyright (c) 2005</p> * <p>Company: gift2u</p> * @author liwu chinajavaworld * @version 1.0 */ import javax.swing.*; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.net.URL; import java.net.*; import java.awt.MediaTracker; import java.io.File; import javax.imageio.ImageIO; import java.io.*; import java.awt.Toolkit; public class PaintPanel extends JPanel { Image image = null; /** * PaintPanel * 外部给图片，直接载入 * @param image Image */ public PaintPanel(Image image) { this.image = image; } /** * PaintPanel * 外部给出file引用,通过ImageIO载入 * @param file File */

public PaintPanel(File file) { try { Image readImage = ImageIO.read(file); this.image = readImage; } catch (IOException ex) { } } /** * PaintPanel *外部给出string路径，通过Toolkit载入 * @param string String */ public PaintPanel(String string) { URL url = null; try { url = new URL(string); } catch (MalformedURLException ex) { } image = Toolkit.getDefaultToolkit().getImage(url); MediaTracker tracker = new MediaTracker(this); tracker.addImage(image, 0); try { tracker.waitForID(0); } catch (InterruptedException ie) { } } /** * PaintPanel *外部给出ImageIcon，利用ImageIcon载入 * @param icon ImageIcon */ public PaintPanel(ImageIcon icon) { this.image = icon.getImage(); } /** * PaintPanel * 外部给出URL，利用ImageIcon载入 * @param icon url */ public PaintPanel(URL url) { ImageIcon icon = new ImageIcon(url); this.image = icon.getImage(); } public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g; if (image != null) { g2d.drawImage(image, 0, 0, this); } } }

　 测试代码:

import javax.swing.JFrame;
import java.net.URL;
import javax.swing.ImageIcon;
import java.awt.MediaTracker;
import java.awt.Image;
import java.net.MalformedURLException;
import java.awt.GridLayout;
import javax.swing.JDialog;
import java.io.File;

public class TestPaintPanel {
 public static void main(String[] args) {
 JFrame fr = new JFrame();
 fr.setTitle("GIFT-PaintPanel-演示载入图片的方法");
 String urlstr = "http://photo.sohu.com/20040823/Img221677764.jpg";
 String filestr="D://a.jpg";
//如果是自己的机器上...un comment following......
//  String urlstr="file:///D://a.jpg";
 URL url = null;
 try {
 url = new URL(urlstr);
 }
 catch (MalformedURLException ex) {
 }

 ImageIcon icon = new ImageIcon(url);

 //////////////////loadimage//////////////////////
 Image image = fr.getToolkit().getImage(url);
 MediaTracker tracker = new MediaTracker(fr);
 tracker.addImage(image, 0);
 try {
 tracker.waitForID(0);
 }
 catch (InterruptedException ie) {}
 ////////////////////////////////////////////////
 fr.getContentPane().setLayout(new GridLayout(2, 2));
 fr.setSize(500, 600);

 fr.getContentPane().add(new PaintPanel(image));
 fr.getContentPane().add(new PaintPanel(urlstr));
 fr.getContentPane().add(new PaintPanel(icon));
 fr.getContentPane().add(new PaintPanel(url));
 //this is a litter different...
 JDialog dialog = new JDialog(fr, "GIFT-演示让图片成为背景", true);
 //本机上的文件...
 dialog.getContentPane().add(new PaintPanel(new File(filestr)));
 dialog.setSize(200, 200);

 fr.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
 fr.setVisible(true);
 dialog.setVisible(true);
 fr.validate();
 }

}