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();
   }

}