Android - getting from a Uri to an InputStream to a byte array?

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!

Solution 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.

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();
}

Solution 2:

With Apache Commons, you can read all the bytes from a Stream thanks to IOUtils.toByteArray(InputStream) as next:

byte[] recordData = IOUtils.toByteArray(inStream);

download jar: http://commons.apache.org/io/download_io.cgi

Solution 3:

Kotlin way:

@Throws(IOException::class)
private fun readBytes(context: Context, uri: Uri): ByteArray? = 
    context.contentResolver.openInputStream(uri)?.buffered()?.use { it.readBytes() }

In Kotlin, they added convenient extension functions for InputStream like buffered, use, and readBytes.

buffered decorates the input stream as BufferedInputStream
use handles closing the stream
readBytes does the main job of reading the stream and writing into a byte array

Error cases:

IOException can occur during the process (like in Java)
openInputStream can return null. If you call the method in Java you can easily oversee this. Think about how you want to handle this case.

Solution 4:

while ((len = inputStream.read(buffer)) != -1)

should be

while (inputStream.available() >0 && (len = inputStream.read(buffer)) != -1)

This way read will not block if stream has no available bytes as explained in this answer.

Solution 5:

With Google Guava, you can use ByteStreams.toByteArray(InputStream) to get all the bytes in the input stream:

InputStream is = ...;
byte[] bytes = ByteStream.toByteArray(is);