WebResponse不返回任何cookies

Question

我目前正在研究一個可以幫助我用cookies和POST參數創建WebRequest的類。但response.cookies總是空的。我如何獲取返回的cookie並將它們發送給下一個請求？

class WebHandler 
{ 
    private string lasturl = ""; 
    private Dictionary<string, Cookie> cookies; 
    public string lastContent; 

    public WebHandler() 
    { 
     cookies = new Dictionary<string, Cookie>(); 
    } 

    public HttpWebResponse request(string address) 
    { 
     lasturl = address; 
     HttpWebRequest request = (HttpWebRequest)WebRequest.Create(address); 
     foreach (KeyValuePair<string, Cookie> pair in this.cookies) 
     { 
      Console.WriteLine(" Sent cookie: " + pair.Value.Name + " = " + pair.Value.Value); 
      request.CookieContainer.Add(pair.Value); 
     } 
     request.Method = "GET"; 
     if(lasturl != "") 
      request.Referer = lasturl; 

     HttpWebResponse response = (HttpWebResponse)request.GetResponse(); 
     foreach (Cookie newCookie in response.Cookies) 
     { 
      Console.WriteLine(" new cookie: " + newCookie.Name + " = " + newCookie.Value); 
      this.cookies[newCookie.Name] = newCookie; 
     } 
     lastContent = new StreamReader(response.GetResponseStream()).ReadToEnd(); 
     return response; 
    } 

    public HttpWebResponse request(string address, Dictionary<string, string> postParameters) 
    { 
     lasturl = address; 
     HttpWebRequest request = (HttpWebRequest)WebRequest.Create(address); 
     foreach (KeyValuePair<string, Cookie> pair in this.cookies) 
     { 
      Console.WriteLine(" Sent cookie: " + pair.Value.Name + " = " + pair.Value.Value); 
      request.CookieContainer.Add(pair.Value); 
     } 
     request.Method = "POST"; 

     string postData = ""; 
     foreach (string key in postParameters.Keys) 
      postData += HttpUtility.UrlEncode(key) + "=" + HttpUtility.UrlEncode(postParameters[key]) + "&"; 


     byte[] data = Encoding.ASCII.GetBytes(postData); 
     request.ContentType = "application/x-www-form-urlencoded"; 
     request.ContentLength = data.Length; 
     Stream requestStream = request.GetRequestStream(); 
     requestStream.Write(data, 0, data.Length); 
     requestStream.Close(); 

     HttpWebResponse response = (HttpWebResponse)request.GetResponse(); 
     foreach (Cookie newCookie in response.Cookies) 
     { 
      Console.WriteLine(" new cookie: " + newCookie.Name + " = " + newCookie.Value); 
      this.cookies[newCookie.Name] = newCookie; 
     } 
     lastContent = new StreamReader(response.GetResponseStream()).ReadToEnd(); 
     return response; 
    } 
} 

Answer 1

如果HttpWebResponse對象的Cookies集合爲空，則意味着響應沒有新的cookies。要訪問請求和響應的所有Cookie，然後讀取來自HttpWebRequest對象餅乾代替，就像這樣：

foreach (Cookie newCookie in request.Cookies) 
{ 
    // Do something with cookies here for next request 
} 

Answer 2

由於this.cookies最初爲null，您的代碼將不會進入循環

foreach (KeyValuePair<string, Cookie> pair in this.cookies) 
{ 
    Console.WriteLine(" Sent cookie: " + pair.Value.Name + " = " + pair.Value.Value); 
    request.CookieContainer.Add(pair.Value); 
} 

不好的一部分，你永遠不會看到request.CookieContainer爲空（否則你會得到空引用異常），這會告訴你什麼是錯的。

由於request.CookieContainer爲空，HttpWebResponse從不會獲取返回的cookie。

解決方案：簡單，只需添加

if (request.CookieContainer == null) 
     request.CookieContainer = new CookieContainer(); 

後

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(address); 

---

PS：你可能需要閱讀this question約在C＃中的命名約定。

PS2：在使用變量名request不提高可讀性的方法request。

Answer 3

我有同樣的問題，所以我加了request.AllowAutoRedirect=false;，我可以讓餅乾：

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(address); 
... 
request.Method = "POST"; 
request.AllowAutoRedirect=false;