关于ImageIO.read

try {
bgImage = ImageIO.read(new File("D:\\image\\background.jpg"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
public void paint(Graphics g){
System.out.println(bgImage);
g.drawImage(bgImage, 0, 0,this);
g.drawString("游戏信息", 100, 60);

}
为什么得到的bgImage总是null,路径没有问题