private static String bytesToHexString(byte[] bytes) {
        StringBuffer sb = new StringBuffer();
        for (byte b : bytes) {
            sb.append(String.format("%02x", b));
        }
        return sb.toString();
    }
Just simple utils.

@author Alexey Danilov (danikula@gmail.com).
dkplayer-videocache/src/main/java/com/danikula/videocache/ProxyCacheUtils.java