C# POST请求demo，contentType 格式：application/x-www-form-urlencoded

/* * url:为请求地址 * postData:请求内容例如："key1=value1&key2=value2&key3=value3" */  public static string PostUrl(string url, string postData)     {         string result = "";         try            {               HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);               req.Method = "POST";               req.ContentType = "application/x-www-form-urlencoded";               req.Timeout = 800;//请求超时时间               byte[] data = Encoding.UTF8.GetBytes(postData);               req.ContentLength = data.Length;               using (Stream reqStream = req.GetRequestStream())               {                   reqStream.Write(data, 0, data.Length);                   reqStream.Close();               }               HttpWebResponse resp = (HttpWebResponse)req.GetResponse();               Stream stream = resp.GetResponseStream();               //获取响应内容               using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))               {                   result = reader.ReadToEnd();               }           }catch(Exception e){}           return result;    }