read file (from downloads directory, or resources) as byte array on android

readbytes.java

    // reads a files content by a given filename and returns it as a byte[]
    // returns null if there are problems reading the file
    public byte[] readBytesFromFileInDownloadsDir(String filename) {

        if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
            // we look for the filename in the "Downloads" directory on the sdcard
            File path = Environment.getExternalStoragePublicDirectory(
                    Environment.DIRECTORY_DOWNLOADS);
            File file = new File(path, filename);

            try {
                return readBytesFromInputStream(new FileInputStream(file), file.length());
            } catch (FileNotFoundException e) {
                Log.e(TAG, "File not found " + e.getMessage());
                return null;
            }
        }
        else {
            Log.e(TAG, "Can't read file. External Storage isn't mounted?");
            return null;
        }
    }

    // reads a raw resource by a given id and returns it as a byte[]
    // returns null if there are problems reading the resource
    public byte[] readBytesFromRawResource(int resourceId) {

        // get an  AssetFileDescriptor to get an inputstream and the length of the file
        AssetFileDescriptor fileDescriptor = getResources().openRawResourceFd(resourceId);

        try {
            return readBytesFromInputStream(fileDescriptor.createInputStream(), fileDescriptor.getLength());
        } catch (IOException e) {
            Log.e(TAG, "Error creating inputstream. " + e.getMessage());
            return null;
        }


    }

    // reads an inputStream and returns it as a byte[]
    // returns null if there are problems reading the inputStream
    public byte[] readBytesFromInputStream(InputStream inputStream, long bytesToRead) {

        if(bytesToRead > Integer.MAX_VALUE) {
            Log.e(TAG, "file is too large to read into byte array");
            return null;
        }

        byte buffer[] = new byte[(int)bytesToRead];

        try {
            if ( inputStream.read(buffer) == -1 ) {
                throw new IOException("EOF reached while reading buffer (bytesToRead: " + bytesToRead);
            }
        } catch (IOException e) {
            Log.e(TAG, "Error reading bytes from inputstream. " + e.getMessage());
            buffer = null;
        } finally {
            try {
                if (inputStream != null)
                    inputStream.close();
            } catch (IOException e) {
                Log.e(TAG, "Error closing inputstream" + e.getMessage());
            }
        }

        return buffer;
}