因为整个系统中需要显示用户一个40*40的小头像，还有一个300*330的大头像，所以就想在用户上传头像时，先把用户上传的源图片，保存起来，经相对路径的形式保存在user类的srcphoto属性中，然后写了一个方法cutImage

public static String cutImage(String srcPath, int width, int height)
            throws IOException {
        File srcFile = new File(srcPath);
        System.out.print(srcFile.exists());
        BufferedImage image = ImageIO.read(srcFile);
        int srcWidth = image.getWidth(null);
        int srcHeight = image.getHeight(null);
        int newWidth = 0, newHeight = 0;
        int x = 0, y = 0;
        double scale_w = (double) width / srcWidth;
        double scale_h = (double) height / srcHeight;
        System.out.println("scale_w=" + scale_w + ",scale_h=" + scale_h);
        // 按原比例缩放图片
        if (scale_w < scale_h) {
            newHeight = height;
            newWidth = (int) (srcWidth * scale_h);
            x = (newWidth - width) / 2;
        } else {
            newHeight = (int) (srcHeight * scale_w);
            newWidth = width;
            y = (newHeight - height) / 2;
        }
        BufferedImage newImage = new BufferedImage(newWidth, newHeight,
                BufferedImage.TYPE_INT_RGB);
        newImage.getGraphics().drawImage(
                image.getScaledInstance(newWidth, newHeight,
                                Image.SCALE_SMOOTH), 0, 0, null);
        // 保存缩放后的图片
        String fileSufix = srcFile.getName().substring(
                srcFile.getName().lastIndexOf(".") + 1);
        File destFile = new File(srcFile.getParent(), UUID.randomUUID()
                .toString()
                + "." + fileSufix);
        // ImageIO.write(newImage, fileSufix, destFile);
        // 保存裁剪后的图片
        ImageIO.write(newImage.getSubimage(x, y, width, height), fileSufix,
                destFile);
        return  UUID.randomUUID().toString()+ "." + fileSufix;
    }

但是将user.srcphoto作为参数传递给此方法时，总是报Can't read input file! 不知道什么原因？