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();
  }

}

: 运行图: