init method
      
void
init(})
      
     
    
初始化服务器地址和端口
Implementation
void init(String host, String port, {String? proxy, OnRequestStart? onStart, bool debug = true,bool printParams = true}) {
  _print = debug;
  _showParams = printParams;
  _ip = host;
  _port = port;
  if (proxy != null) _proxy = proxy;
  _onStart = onStart;
}