HttpWebRequest.GetResponse() 抛出“错误请求”400 错误

Question

以下是示例代码（更改了实际 URL 和凭据）

ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback((object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) => { return true; }); 

var requestUri = new Uri("https://example.com/path1/path2?var=somevar");

byte[] data = Encoding.UTF8.GetBytes("DEV72*12/27/06*TAYLOR*RICH*JOE*10/28/56*U0999495102*466666666*01*TAYLOR*TAMMY*M*10/26/52***CIGNA HMO*62308*UPIN*MEDICAL CENTER**MESSAGE*M*F*30");
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(requestUri);
request.PreAuthenticate = true;
request.UseDefaultCredentials = false;
request.Credentials = new NetworkCredential("UUUSSSEEERR", "PASSWORD");
request.ContentLength = data.Length;
request.ContentType = "text/plain";
request.Method = "POST";

using (Stream stream = request.GetRequestStream())
{
   stream.Write(data, 0, data.Length);
   stream.Flush();
}

StreamReader streamReader = null;

string result;
try
{
   streamReader = new StreamReader(request.GetResponse().GetResponseStream());
   result = streamReader.ReadToEnd();
}
finally
{
   streamReader.Close();
}

txtOutput.Text = result;

它总是在第一次运行时抛出错误的请求异常，但是当我将调试器中的光标移回第一行时，它工作正常，并在 txtOutput.text 中给出正确的响应，并且在分离的应用程序中提供相同的行为，第一次抛出异常，但第二次它工作正常，有人可以给我一些解决办法，或者让我知道我在这里做错了什么。 使用.net 4.0。

更新：

例如，以下代码对我有用，但这不是我正在寻找的解决方法，我只是通过捕获 WebException 添加了一个 while 循环，如果其 statusCode 为 400，我重新循环该代码并且它可以工作

var requestUri = new Uri("https://example.com/path1/path2?var=somevar");

ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback((object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) => { return true; }); 

byte[] data = Encoding.UTF8.GetBytes("DEV72*12/27/06*TAYLOR*RICH*JOE*10/28/56*U0999495102*466666666*01*TAYLOR*TAMMY*M*10/26/52***CIGNA HMO*62308*UPIN*MEDICAL CENTER**MESSAGE*M*F*30");
HttpWebRequest request = null;  
int counter = 0;
do
{
    request = (HttpWebRequest)WebRequest.Create(requestUri);

    request.PreAuthenticate = true;
    request.UseDefaultCredentials = false;
    request.Credentials = new NetworkCredential("USERNAME", "password");
    request.ContentLength = data.Length;
    request.ContentType = "text/plain";
    request.Method = "POST";

    using (Stream stream = request.GetRequestStream())
    {
        stream.Write(data, 0, data.Length);
        stream.Flush();
    }

    StreamReader streamReader = null;

    string result = string.Empty;
    try
    {
        streamReader = new StreamReader(request.GetResponse().GetResponseStream());
        result = streamReader.ReadToEnd();
    }
    catch (WebException ex)
    {
        HttpWebResponse response = (HttpWebResponse)ex.Response;
        if (response.StatusCode == HttpStatusCode.BadRequest)
        {
            counter++;
        }
        else
        {
            txtOutput.Text = ex.ToString();
        }
    }
    finally
    {
        if(streamReader != null) streamReader.Close();
    }

    txtOutput.Text = result;

} while (counter == 1);

Answer 1

一个流。Close();在stream.Flush()之后；可能会有所帮助