Question

I’m trying to get from an Android Uri to a byte array.

I have the following code, but it keeps telling me that the byte array is 61 bytes long, even though the file is quite large – so I think it may be turning the Uri string into a byte array, rather than the file 🙁

  Log.d(LOG_TAG, "fileUriString = " + fileUriString);
  Uri tempuri = Uri.parse(fileUriString);
  InputStream is = cR.openInputStream(tempuri);
  String str=is.toString();
  byte[] b3=str.getBytes();
  Log.d(LOG_TAG, "len of data is " + imageByteArray.length
     + " bytes");

Please can someone help me work out what to do?

The output is “fileUriString = content://media/external/video/media/53” and “len of data is 61 bytes”.

Thanks!

Answer 1

is.toString() will give you a String representation of the InputStream instance, not its content.

You need to read() bytes from the InputStream into your array. There’s two read methods to do that, read() which reads a single byte at a time, and read(byte[] bytes) which reads bytes from the InputStream into the byte array you pass to it.

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Update: to read the bytes given that an InputStream does not have a length as such, you need to read the bytes until there is nothing left. I suggest creating a method for yourself something like this is a nice simple starting point (this is how I would do it in Java at least).

public byte[] readBytes(InputStream inputStream) throws IOException {
  // this dynamically extends to take the bytes you read
  ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream();

  // this is storage overwritten on each iteration with bytes
  int bufferSize = 1024;
  byte[] buffer = new byte[bufferSize];

  // we need to know how may bytes were read to write them to the byteBuffer
  int len = 0;
  while ((len = inputStream.read(buffer)) != -1) {
    byteBuffer.write(buffer, 0, len);
  }

  // and then we can return your byte array.
  return byteBuffer.toByteArray();
}