@Override
 public void onFailure(Throwable t, int errorNo, String strMsg) {
   super.onFailure(t, errorNo, strMsg);
   if (null != downloadCallback) {
     downloadCallback.onFailure(errorNo, strMsg);
   }
 }
 @Override
 public void onLoading(long count, long current) {
   super.onLoading(count, current);
   if (null != downloadCallback) {
     downloadCallback.onProgress(current, count, "");
   }
 }
 @Override
 public void onSuccess(File file) {
   super.onSuccess(file);
   if (null != downloadCallback) {
     downloadCallback.onDownLoadSuccess(file.getAbsolutePath());
   }
 }