How to convert an image to an array of bytes in java?

Question

How to convert an image to an array of bytes in java?

Navigation

#1 by (2 votes)
#2 by (0 votes)

1

I'm trying to convert an image to an array of bytes in java to save it in a database, I used several methods to perform the conversion, and you could say that if it does, but it always returns a small part, this one of the codes that I have occupied:

public byte[] extractBytes(File imgPath) throws IOException {

        BufferedImage bufferedImage = ImageIO.read(imgPath);

        RecortaFotografia recorte = new RecortaFotografia(bufferedImage, 100, 100);

        WritableRaster raster = bufferedImage.getRaster();
        DataBufferByte data = (DataBufferByte) raster.getDataBuffer();

        return (data.getData());
    }

But the result is always something similar to this:

[B@172675af

I have used other methods for conversion and the result is always the same. I do not find my mistake, or what I'm doing wrong. Why do you always return only part of me? or how can I get the entire string of the byte array?

mysql java netbeans

asked by Ken 08.10.2016 в 01:11

source

2 answers

Infix to postfix in Java [closed] Why do I have this error hiding this MenuItem?

score 2 · Answer 1

But the result is always something similar to this:
[B@172675af

It is completely normal why you are printing a object . When you print an object - if you have not overwritten the toString method, what you will get is:

NombreClase@hashcode

These are basic notions. To print your byte array you should do a simple for:

for(byte b : bytes) { System.out.print(b); }

Or lambda style:

Arrays.stream(bytes).forEach(System.out::print);

An easy way to convert an image to byte[] is this:

public static Optional<byte[]> toBinary(String path) {
    int len = path.split("\.").length;
    String ext = path.split("\.")[len - 1];
    try {
        BufferedImage img = ImageIO.read(new File(path));
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ImageIO.write(img, ext, baos);
        return Optional.of(baos.toByteArray());
    } catch(IOException e) {
        return Optional.empty();
    }
}

And we would use it like this:

Optional<byte[]> binary = ImageUtils.toBinary("ruta-abs-imagen");
// la imagen se procesó sin problemas y hay datos
if(binary.isPresent()) {
    byte[] image = binary.get();
}

score 0 · Answer 2

The result is the value of Objeto that your method returns, maybe you get the value as follows

/* Por eso Obtienes ese valor */
System.out.println(extractBytes(new File("urlImage")));

The first part of this output shows the Object Type where appropriate B that is Byte
The second part is the representation hexadecimal of the hashCode () of your object. (172675af)

To obtain the values returned by your método you should receive them before .. a simple way to do this operation would be.

   byte[] retorno = extractBytes(new File("urlfile"));
    /* Imprimir los Bytes */
    for (byte s : retorno) {
        System.out.println(s& 0xff); 
     /* Si quiere hacer sus valores Positivos sino simplemente sout(s) */
    }

Another way to print (If you want to do it) would be to use the class Arrays and its method toString (byte [] array)