从Base64到ImageIO

Question

I'm trying to convert a base64 string to an imageIO and saving it.

In a bigger context, I'm creating a script so users can upload an image, crop it and save it as their profile image. I get a Base64 String from this cropped image, and sent it to the servlet. (Yes, I'm using Java Server Pages)

Here is the problem: When i execute the following code, i get a null pointer on my variable Image in the method decodeToImage .

I tried to use several other libraries to decode the base64 but with no results yet. I tried to use other image convert scripts but none worked.

Also this code seems to me that is should work. Am i missing something?

Thanks in advance!

All reactions are welcome!

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);

    if(request.getParameter("upload-CroppedImage") != null){


        BufferedImage newImage = decodeToImage(request.getParameter("croppedImage"));

        File outputfile = new File("F:\\Users\\Joery v2\\Pictures\\saved.jpg");
        ImageIO.write(newImage, "jpg", outputfile);
    }
}

public static BufferedImage decodeToImage(String imageString) {

    try {
        byte[] imgBytes = parseBase64Binary(imageString);
         BufferedImage image = ImageIO.read(new ByteArrayInputStream(imgBytes));
         return image;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

*This is code from the servlet.

Stack Trace:

Info:   GameZ_Website was successfully deployed in 2.076 milliseconds.
Warning:   StandardWrapperValve[CroppingImage]: Servlet.service() for servlet CroppingImage threw exception
java.lang.IllegalArgumentException: image == null!
    at javax.imageio.ImageTypeSpecifier.createFromRenderedImage(ImageTypeSpecifier.java:925)
    at javax.imageio.ImageIO.getWriter(ImageIO.java:1592)

Answer 1

Try this code, to avoid the decode/encode cycle, and see if your image looks as expected:

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);

    if (request.getParameter("upload-CroppedImage") != null) {
        String dataURI = request.getParameter("croppedImage");
        String data = dataURI.substring(dataURI.indexOf(',')); // TODO: Input validation
        byte[] imgBytes = parseBase64Binary(data);

        File outputfile = new File("F:\\Users\\Joery v2\\Pictures\\saved.jpg");
        writeBytesToFile(imgBytes, outputFile);
    }
}

private void writeBtesToFile(byte[] bytes, File file) {
    OutputStream out;

    try {
        out = new FileOutputStream(file);
        out.write(bytes);
    } 
    finally {
        out.close();
    }
}