operate method
This method is used to request the other insterface but login.
param
For building the request paramaters. You should use the implemented class.
Implementation
Future<Map<String, dynamic>> operate(RequestParam param) async {
if (_domain == null) throw Exception("domain msut be not null");
String url = _domain! + _prefix + param.getRequestPath() + _suffix;
var resp = await _postJson(url, jsonEncode(param.toJson()));
if (resp.statusCode != HttpStatus.ok) throw Exception("http error, http status code is ${resp.statusCode}.");
String body = await resp.transform(utf8.decoder).join();
return param.parseResponse(body);
}