使用HttpWebRequest时出现缺失的POST数据

Question

我在使用 HttpWebRequest 发送数据时遇到了问题。

我有一个字符串（例如，key1=value1&key2=value2&key3=value3），我要将其提交到一个网站（例如，www.*.com/edit）。但是有时候没事，而有时候只有key2=value2&key3=value3在HttpAnalyzer中能找到，而第一个key1=value1却不见了。请帮忙查看这个问题的原因。

public static string SubmitData(string Url, string FormData, CookieContainer _Cc, string ContentType)
        {
            Stream RequestStream = null, ResponseStream = null; StreamReader Sr = null;
            HttpWebRequest HRequest = (HttpWebRequest)WebRequest.Create(Url);
            try
            {

                HRequest.CookieContainer = _Cc;
                HRequest.Method = "POST";
                HRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0)";
                HRequest.ContentType = ContentType;
                HRequest.ContentLength = FormData.Length;
                //byte[] BFromData = new ASCIIEncoding().GetBytes(FormData);
                byte[] BFromData = Encoding.ASCII.GetBytes(FormData);
                BFromData = Encoding.Convert(Encoding.ASCII, Encoding.UTF8, BFromData);//ascii → utf8
                RequestStream = HRequest.GetRequestStream();
                RequestStream.Write(BFromData, 0, BFromData.Length);
                //RequestStream.Write(utf8Bytes,0,utf8Bytes.Length );
                HttpWebResponse HResponse = (HttpWebResponse)HRequest.GetResponse();
                ResponseStream = HResponse.GetResponseStream();
                Sr = new StreamReader(ResponseStream, Encoding.UTF8);
                return Sr.ReadToEnd();
            }
            catch
            {
                return "";
            }
            finally
            {
                if (null != RequestStream) RequestStream.Close();
                if (null != ResponseStream) ResponseStream.Close();
                if (null != Sr) Sr.Close();
            }
        }

- SheldonLou

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你能展示一下你要发布的链接的例子吗？ - Rob

Answer 1

使用Fiddler查看在单击表单时请求的外观，然后尝试使用此方法并根据需要修改您的请求。

public static void PostDataAndDoSomething()
        {            
            string URI = "http://www.something.com";
            //make your request payload
            string requestBody = String.Format("{{'param1': {0}, 'param2': {1}}}",value1, value2); //json format

            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(URI);  //make request         

            // set request headers as you need
            request.ContentType = "application/json; charset=UTF-8"; 
            request.Accept = "application/json, text/javascript;
            request.Method = "POST";            
            request.UserAgent = "";
            request.Headers.Add("X-Requested-With", "XMLHttpRequest");
            using (StreamWriter writer = new StreamWriter(request.GetRequestStream()))
            {
                writer.Write(requestBody); //write your request payload
            }

            WebResponse response = request.GetResponse();          
            string jsonData = String.Empty;

            using (var reader = new StreamReader(response.GetResponseStream()))
            {
                jsonData = reader.ReadToEnd();
            }           
            response.Close();

            //do something with your data, deserialize, Regex etc....
        }

- Matija Grcic

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@HelloWorld，你能给我发布数据的链接吗？ - Matija Grcic

这是一个需要登录的网站。 - SheldonLou

那么我只能说，我的答案适用于在POST（ajax请求等）后获取响应的情况，并且您应该使用Fiddler分析HTTP流量，以查看您在哪里犯了错误。 - Matija Grcic

首先，非常感谢您的建议。其次，我认为“缺失数据”可能会误导我。 - SheldonLou