HttpWebRequest 多部分表单数据

Question

我正在尝试将简单的文本数据提交到多部分形式的 CGI。

问题是..我不知道如何格式化表单数据！

简而言之，我的系统准备一个包含 post 数据的字符串，使用 request.GetRequestStream() 创建一个流编写器，然后直接将 post 字符串写入该流编写器。然后它继续关闭流编写器并发送请求。

我尝试将字符串格式化为：“Param1=sometext&param2=sometext”，但返回错误：

Unhandled Exception: System.Net.WebException: The remote server returned an error: (417) Expectation Failed.
  at System.Net.HttpWebRequest.CheckFinalStatus (System.Net.WebAsyncResult result) [0x002d9] in /private/tmp/monobuild/build/BUILD/mono-2.8/mcs/class/System/System.Net/HttpWebRequest.cs:1425 
  at System.Net.HttpWebRequest.SetResponseData (System.Net.WebConnectionData data) [0x00143] in /private/tmp/monobuild/build/BUILD/mono-2.8/mcs/class/System/System.Net/HttpWebRequest.cs:1250 

显然我格式化字符串错误，但我一生都无法弄清楚如何正确执行此操作。

有人可以启发我吗？ :)

编辑，我还尝试将 request.ContentType = "application/x-www-form-urlencoded"; 更改为 request.ContentType = "multipart/form-data";。这没有任何作用，但我打算就这样。

编辑：完整代码：

public static string sendReq (string url, string pdata)//Pdata is the string containing form data
{
    StringBuilder sb  = new StringBuilder();
    byte[] buf = new byte[8192];
    HttpWebRequest request  = (HttpWebRequest) WebRequest.Create(url);
    CookieCollection jar = new CookieCollection();
    jar.Add(new Cookie("Cookie","Data","Removed","For privacy."));
    jar.Add(new Cookie("Cookie","Data","Removed","For privacy."));
    jar.Add(new Cookie("Cookie","Data","Removed","For privacy."));
    jar.Add(new Cookie("Cookie","Data","Removed","For privacy."));
    jar.Add(new Cookie("Cookie","Data","Removed","For privacy."));
    l("Loading cookie jar onto request");
    CookieContainer cont = new CookieContainer();
    cont.Add(jar);
    request.CookieContainer = cont;
    if (pdata != "")
    {
        request.Method = "POST";
        request.ContentType = "multipart/form-data;";
        request.ContentLength = pdata.Length;
        StreamWriter stOut = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
        stOut.Write(pdata);
        stOut.Close();
    }
    HttpWebResponse response = (HttpWebResponse) request.GetResponse();
    Stream resStream = response.GetResponseStream();
    string tempString = null;
    int count = 0;
    do
    {
        count = resStream.Read(buf, 0, buf.Length);
        if (count != 0)
        {
            l("Data was read. ["+count+" bytes]. Encoding to ASCII");
            tempString = Encoding.ASCII.GetString(buf, 0, count);
            l("Appending to full string");
            sb.Append(tempString);
        }
    }
    while (count > 0);
    return sb.ToString();
}

处理发送帖子数据的代码部分：

if (pdata != "")
    {
        request.Method = "POST";
        request.ContentType = "multipart/form-data;";
        request.ContentLength = pdata.Length;
        StreamWriter stOut = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
        stOut.Write(pdata);
        stOut.Close();
    }
    HttpWebResponse response = (HttpWebResponse) request.GetResponse();

Answer 1

尝试：

System.Net.ServicePointManager.Expect100Continue = false;

显然，HttpWebRequest默认添加了Expect标头，这让很多服务器感到困惑。

更新：

恢复为：

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

因为内容类型和正文中的数据的当前组合不匹配。