我面临错误 Stream.Length throws NotSupportedException

Question

我正在尝试使用HttpWebRequest 对象将一些数据从 ASP.Net 应用程序发布到 PHP。但是当我尝试使用

阅读 Request 内容时

Stream myStream = myWebReq.GetRequestStream();

我收到一个错误

“responseStream.Length”引发了“System.NotSupportedException”类型的异常。
Length = 'dataStream.Length' 引发了“System.NotSupportedException”类型的异常
Position = 'dataStream.Position' 引发了“System.NotSupportedException”类型的异常

这里是代码

string strURL = null;
HttpWebRequest myWebReq = default(HttpWebRequest);
HttpWebResponse myWebResp = default(HttpWebResponse);

byte[] byteData = null;
StreamReader sr = default(StreamReader);
strURL = "http://people.com.pk/nppm/hrms_ppm_service.php?dump=1";
myWebReq = (HttpWebRequest)WebRequest.Create(strURL);
myWebReq.ContentType = "application/x-www-form-urlencoded; charset=utf-8";
myWebReq.Method = "POST";

Label1.Text = Newtonsoft.Json.JsonConvert.SerializeObject(batches).ToString();

byteData = UTF8Encoding.UTF8.GetBytes(Label1.Text);
myWebReq.ContentLength = byteData.Length;

myWebReq.KeepAlive = true;

if (myWebReq.Proxy != null)
{
   myWebReq.Proxy.Credentials = CredentialCache.DefaultCredentials;
}

Stream myStream = myWebReq.GetRequestStream();

if (byteData.Length > 0)
{
   myStream.Write(byteData, 0, byteData.Length);
   myStream.Close();
}

myWebResp = (HttpWebResponse)myWebReq.GetResponse();
sr = new StreamReader(myWebResp.GetResponseStream());
string strJSON__2 = sr.ReadToEnd();
Label1.Text = strJSON__2;

Answer 1

只需检查您的 HttpWebRequest.DefaultCachePolicy 属性即可。
正如documentation 建议的那样，HttpWebRequest.GetRequestStream 方法只会在请求缓存验证器指示可以从缓存中提供请求的响应时抛出NotSupportedException；但是，写入数据的请求不得使用缓存。如果您使用了未正确实现的自定义缓存验证器，则可能会发生此异常。