public R paramsToMultipartEntity(){
  try {
    mHttpEntity=createMultipartEntity(false);
  }
 catch (  IOException e) {
    e.printStackTrace();
  }
  return (R)this;
}

public R paramsToMultipartEntity ( ) { try { mHttpEntity = createMultipartEntity ( false ) ; } catch ( IOException e ) { e . printStackTrace ( ) ; } return ( R ) this ; }
convert params to multipart entity .
