fetch method
**
- 发送请求
Implementation
@VoltronMethod(kFetchMethodName)
bool fetch(final VoltronMap request, final JSPromise promise) {
VoltronHttpAdapter adapter = context.globalConfigs.httpAdapter;
adapter.init(
context: context,
requestWillBeSentHook: requestWillBeSentHook,
responseReceivedHook: responseReceivedHook,
);
adapter.doFetch(request, promise);
return true;
}