记录一次 HttpWebRequest 尝试自动重定向太多 错误

 

 当使用HttpWebRequest进行访问时，结果提示为302重定向错误。

使用代码，

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "GET";
request.ContentType = "text/html";
request.AllowAutoRedirect = true;//设置自动重定向
 
request.ServicePoint.Expect100Continue = true;//设置自动重定向
request.MaximumAutomaticRedirections = 50;//允许最大重定向次数
request.CookieContainer = new CookieContainer();
//request.Timeout = 30000;
//request.ReadWriteTimeout = 30000;
 
ServicePointManager.ServerCertificateValidationCallback += (se, cert, chain, sslerror) =>
{
    return true;
};
 
request.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36";
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
var heards = request.GetResponse().Headers;
Stream myResponseStream = response.GetResponseStream();
using (StreamReader myStreamReader = new StreamReader(myResponseStream, encoding))
{
    string retString = myStreamReader.ReadToEnd();
    myStreamReader.Close();
    myResponseStream.Close();
    return retString;
}

最终发现。是少加了CookieContainer...猜测是由于重定向时候第一个网页往头部添加了一个Cookie这个Cookie发送给重定向地址，所以必须带上CookieContainer。