Java从Bytearray创建BufferedImage

Question

What I'm trying to do is create a BufferedImage from a byte array. Here is what I'm doing now:

    try {
        ByteArrayInputStream in = new ByteArrayInputStream(bytearray);
        BufferedImage bImageFromConvert = ImageIO.read(in);

        Color color = new Color(bImageFromConvert.getRGB((int) local_car.x, (int) local_car.z));
        System.out.println("R :: "+color.getRed() + " B :: "+color.getBlue() + " G :: "+color.getGreen());
    } catch (IOException e) {
        e.printStackTrace();
    }
}

The documentation of ImageIO.read says:

Returns a BufferedImage as the result of decoding a supplied URL with an ImageReader chosen automatically from among those currently registered. An InputStream is obtained from the URL, which is wrapped in an ImageInputStream. If no registered ImageReader claims to be able to read the resulting stream, null is returned.

I'm receiving a null pointer exception from ImageIO.read() returning null . I am sending my bytearray in the form of RGBA. Why is ImageIO.read returning null?

Answer 1

The ImageIO functions are for reading files and expect the input stream to be in one of the file formats such as PNG or JPG, not for reading simple arrays of rgba. To read in a simple array try something like:

int width = 256;
int height = 256;
final int bytes_per_pixel = 4;
byte[] raw = new byte[width * height * bytes_per_pixel];
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
IntBuffer intBuf
        = ByteBuffer.wrap(raw)
        .order(ByteOrder.LITTLE_ENDIAN)
        .asIntBuffer();
int[] array = new int[intBuf.remaining()];
intBuf.get(array);
image.setRGB(0, 0, width, height, array, 0, width);