的JPanel与背景图像

Question

我有以下代码：

class ImagePanel extends JPanel { 

      private Image img; 

      public ImagePanel(String img) { 
      this(new ImageIcon(img).getImage()); 
      } 

      public ImagePanel(Image img) { 
      this.img = img; 
      Dimension size = new Dimension(img.getWidth(null), img.getHeight(null)); 
      setPreferredSize(size); 
      setMinimumSize(size); 
      setMaximumSize(size); 
      setSize(size); 
      setLayout(null); 
      } 

      public void paintComponent(Graphics g) { 
      g.drawImage(img, 0, 0, null); 
      } 
     } 

及以下：

public GUIVenDetails() throws MalformedURLException, IOException{ 

     mapPanel = new ImagePanel("http://www.netstate.com/states/symb/gamebirds/images/wild_turkey.jpg"); 
     mapPanel.setPreferredSize(new Dimension(200,200)); 
     mapPanel.setMinimumSize(mapPanel.getPreferredSize()); 
     mapPanel.setMaximumSize(mapPanel.getPreferredSize()); 


     add(mapPanel); 
    } 

public static void main(String[] args) throws MalformedURLException, IOException, XPathExpressionException, SAXException, ParserConfigurationException { 


     GUIVenDetails gui = new GUIVenDetails(); 

     Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); 
     Dimension windowSize = gui.getSize(); 

     int windowX = Math.max(0, (screenSize.width - windowSize.width)/2); 
     int windowY = Math.max(0, (screenSize.height - windowSize.height)/2); 

     JFrame f=new JFrame(); 
     f.setSize(new Dimension(400,800)); 
     f.setLocation(windowX, windowY); 

     f.add(gui); 
     f.setVisible(true); 
    } 

当我运行代码，我没有看到任何东西，但白...为什么这是？

Answer 1

这不是你如何从互联网上读取文件。尝试是这样的：

String imagePath = "http://duke.kenai.com/misc/Bullfight.jpg"; 
Image image = null; 

try 
{ 
    URL url = new URL(imagePath); 
    image = ImageIO.read(url); 
} 
catch (IOException e) 
{ 
    System.out.println(e); 
} 

或者你仍然可以使用

new ImageIcon(new URL(...)); 

但是，仅仅因为它以“http”开头的字符串不会成为一个URL。