【C#MVC】 使用HttpWebRequest访问外部API，并返回json信息 (Access_Key)

在c#中调用外部API或者自己系统的API都是很简单的，这里提供使用HttpWebRequest的方式访问外部API，自定义了头部Access_key.
若外部系统没有此安全验证，可以去掉。

        public string OpenReadWithHttps(string URL, string strPostdata, string strEncoding)        {            Encoding encoding = Encoding.Default;            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);            request.Method = "post";            request.Headers.Add("access_key", "your access_key");            request.Accept = "application/json";            request.ContentType = "application/json; charset=utf-8";            byte[] buffer = Encoding.ASCII.GetBytes(strPostdata);            request.ContentLength = buffer.Length;            request.GetRequestStream().Write(buffer, 0, buffer.Length);            HttpWebResponse response = (HttpWebResponse)request.GetResponse();            using (StreamReader reader = new StreamReader(response.GetResponseStream(), encoding))            //System.Text.Encoding.GetEncoding(strEncoding)            {                return reader.ReadToEnd();            }        }