如何调用外部的Web API

Uri uri = new Uri(url + "?" + postData);

System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(uri);

request.Method = "GET";

request.ContentType = "application/x-www-form-urlencoded";

request.AllowAutoRedirect = false;

request.Timeout = 5000;

System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();

Stream responseStream = response.GetResponseStream();

StreamReader readStream = new StreamReader(responseStream, System.Text.Encoding.UTF8);

string retext = readStream.ReadToEnd().ToString();

readStream.Close();

return retext;

}