Java converting byte[] to image

问题:

I know this seems like a common question but i have looked all over the internets, and tried many different tutorials and methods for doing this. I think i am close, but not sure. Also i am using Play Framework but it should be the same for java. here is my error

javax.image.IIOException: I/O error reading PNG header!
   at com.sun.plugins.png.PNGImageReader.readHeader(Unknown Source)
   ...
   ...
Caused by: java.io.EOFException
at javax.imageio.stream.ImageInputStreamImpl.readFully(Unknown Source)
  ...

Here is my code where i get the picture among other things from a form and convert the image to a byte[] and store in MS SQL db.

@Transactional
public static Result submitTrailer(){
     filledForm = newTrailerForm.bindFromRequest();
     MultipartFormData body = request().body().asMultipartFormData();
     FilePart picture = body.getFile("file");
     String fileName = picture.getFilename();
     System.out.println(fileName);
     String contentType = picture.getContentType(); 
     System.out.println(contentType);
     final File file = picture.getFile();
     filledForm.get().setContentType(contentType);

     try{
     BufferedImage originalImage = ImageIO.read(file);
     ByteArrayOutputStream baos = new ByteArrayOutputStream();
     ImageIO.write(originalImage, contentType, baos);

     filledForm.get().setImage(baos.toByteArray());
     baos.flush();
     baos.close();
     filledForm.get().save();
     }catch(IOException e){
         e.printStackTrace();
     }

    return ok(views.html.index.index.render());
}

here is where i am trying to covert the byte[] back to an image so i can display it in html

public File getConvertedPicture(){
    File imageFile;
    System.out.println("byteToImage() called");
    if(getImage()==null){
        System.out.println("getByteImage()==null");
        return null;

    }else{
        try{
        ByteArrayInputStream bis = new ByteArrayInputStream(getImage());
        imageFile=File.createTempFile("pattern", ".suffix");

        Iterator<?> readers = ImageIO.getImageReadersByFormatName("PNG");


        ImageReader reader = (ImageReader) readers.next();
         Object source = bis;
         ImageInputStream iis = ImageIO.createImageInputStream(source);
         reader.setInput(iis, true);
            ImageReadParam param = reader.getDefaultReadParam();

            Image image = reader.read(0, param);
            BufferedImage bufferedImage = new BufferedImage(image.getWidth(null), image.getHeight(null), BufferedImage.TYPE_INT_RGB);
            Graphics2D g2 = bufferedImage.createGraphics();
            g2.drawImage(image, null, null);

            ImageIO.write(bufferedImage,"PNG", imageFile);
            return imageFile;

        }
        catch(IOException e){
            e.printStackTrace();
            return null;
        }
    }

I am a beginner, this is my first time using play, and first time using databases. Any advice to get this to work would be greatly appreciated.

also, in my method getConvertedPicture() i have to specify the format type, is there anyway to get around this so the user can upload any type of picture they want.

回答1:

Try to use

byte[] byteArray=null; //need to initialize it
ImageIcon imageIcon = new ImageIcon(byteArray);
imageIcon.getImage();

回答2:

To convert bytes to an image without knowing the file type I usually do:

ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
BufferedImage image = ImageIO.read(bais);

That will return a BufferedImage that you can save into any picture format such as jpg.

To write the image back out to a byte array:

ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(image, "jpg", baos);
byte [] bytes = baos.toByteArray();

回答3:

To convert an array of bytes, i.e. byte[] into an image, use getImage(). Probably the easiest way to do this is to instantiate an ImageIcon using the ImageIcon(byte[]) constructor, and then call getImage(). This is illustrated in the method below, particularly the last line:

public Image createImage(){
   byte[] b = {-119, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82,
      0, 0, 0, 15, 0, 0, 0, 15, 8, 6, 0, 0, 0, 59, -42, -107,
      74, 0, 0, 0, 64, 73, 68, 65, 84, 120, -38, 99, 96, -64, 14, -2,
      99, -63, 68, 1, 100, -59, -1, -79, -120, 17, -44, -8, 31, -121, 28, 81,
      26, -1, -29, 113, 13, 78, -51, 100, -125, -1, -108, 24, 64, 86, -24, -30,
      11, 101, -6, -37, 76, -106, -97, 25, 104, 17, 96, -76, 77, 97, 20, -89,
      109, -110, 114, 21, 0, -82, -127, 56, -56, 56, 76, -17, -42, 0, 0, 0,
      0, 73, 69, 78, 68, -82, 66, 96, -126};
   return new ImageIcon(b).getImage();
}

I think this can by used for png, gif, bmp, and jpg images. The byte array does not have to be hard-coded, as in this example.

Additionally, new ImageIcon("image.png").getImage() can be used to load a displayable image from a file, where image.png is the filename.