c# - 此属性不能在写入开始后设置!在 C# WebRequest 对象上

Question

我想重用 WebRequest 对象，以便保存 cookie 和 session 以供以后向服务器请求。下面是我的代码。如果我在

第二次使用 Post 函数两次

request.ContentLength = byteArray.Length;

会抛出异常

This property cannot be set after writing has started!

但如你所见

dataStream.Close();

应该关闭写入进程!有人知道发生了什么吗？

static WebRequest request;

public MainForm()
{
    request = WebRequest.Create("http://localhost/admin/admin.php");
}

static string Post(string url, string data) 
{
    request.Method = "POST";
    byte[] byteArray = Encoding.UTF8.GetBytes(data);
    request.ContentType = "application/x-www-form-urlencoded";
    request.ContentLength = byteArray.Length;
    Stream dataStream = request.GetRequestStream();
    dataStream.Write(byteArray, 0, byteArray.Length);
    dataStream.Close();
    WebResponse response = request.GetResponse();
    Console.WriteLine(((HttpWebResponse)response).StatusDescription);
    dataStream = response.GetResponseStream();
    StreamReader reader = new StreamReader(dataStream);
    string responseFromServer = reader.ReadToEnd();
    Console.WriteLine(responseFromServer);
    reader.Close();
    dataStream.Close();
    response.Close();
    request.Abort();
    return responseFromServer;
}

Answer 1

您不能重复使用 WebRequest。取返回的HttpWebResponse.Cookies , 构造一个新的 WebRequest 并填充 HttpWebRequest.CookieContainer . (您需要在第一个请求中分配一个 CookieContainer 以获取返回的 Cookie。)