public String getUrl() {
   if (LockerId.class.isInstance(mId)) {
     if (mFileKey == null) getFileKey();
     RemoteMethod method;
     try {
       method =
           new RemoteMethod.Builder(RemoteMethod.METHODS.LOCKER_GET).addFileKey(mFileKey).create();
     } catch (InvalidSessionException e) {
       e.printStackTrace();
       return null;
     }
     return method.getCall();
   } else {
     return mPlayUrl;
   }
 }
 public String getPlayUrl(String container, int requestedBitrate) {
   if (LockerId.class.isInstance(mId)) {
     if (mFileKey == null) getFileKey();
     if (container == null) container = "mp3";
     RemoteMethod method;
     try {
       method =
           new RemoteMethod.Builder(RemoteMethod.METHODS.LOCKER_PLAY)
               .addFileKey(mFileKey)
               .addParam("fileformat", container)
               .addParam("bitrate", Integer.toString(requestedBitrate))
               .create();
     } catch (InvalidSessionException e) {
       e.printStackTrace();
       return null;
     }
     return method.getCall();
   } else {
     return mPlayUrl;
   }
 }