发送HTTP标头后,服务器无法修改cookie,如何修复？

Question

如果Cookie中存在UserName和Password,我想在masterpage的page_load上自动登录我的用户!
所以我写下面的代码:

        protected void Page_Load(object sender, EventArgs e)
        {
            LoadDataFromCookieIfExistAndLogin();
        }

private void LoadDataFromCookieIfExistAndLogin()
{
    string Query = Request.Url.Query.ToString();
    string[] Ar_Query = new string[2];
    string[] splitter = { "%2f" };
    Ar_Query = Query.Split(splitter, System.StringSplitOptions.None);
    string[] Ar_new_Query = new string[2];
    int minLength = Math.Min(Ar_Query.Length, Ar_new_Query.Length);
    Array.Copy(Ar_Query, Ar_new_Query, minLength);
    if (string.IsNullOrEmpty(Ar_new_Query[1]))
    {
        Ar_new_Query[1] = string.Empty;
    }

    if ((Request.QueryString["ReturnURL"] != null) && (Ar_new_Query[1].ToString().ToUpper() == "ADMIN"))
    {
        Session.Clear();
        FormsAuthentication.SignOut();
    }
    else if ((Request.QueryString["ReturnURL"] != null) && (Ar_new_Query[1].ToString().ToUpper() == "ELMAH.AXD"))
    {
        Session.Clear();
        FormsAuthentication.SignOut();
    }
    else
    {
        HttpCookie Situation_Cookie = Request.Cookies["Situation"];
        if (Situation_Cookie != null)
        {
            if (Situation_Cookie["Login"] == "Yes")
            {
                HttpCookie Data_Cookie = Request.Cookies["Data"];
                if (Data_Cookie != null)
                {
                    string UserName = Data_Cookie["UserName"].ToString();
                    string PassWord = ata_Cookie["PassWord"].ToString();

                    string HashedPass = FormsAuthentication.HashPasswordForStoringInConfigFile(PassWord, "MD5");
                    DataSet dsUsers = DataLayer.Users.SelectRowForLogin_FromCookie(UserName, HashedPass);
                    if (dsUsers.Tables["Users"].Rows.Count > 0)
                    {
                        DataRow drUsers = dsUsers.Tables["Users"].Rows[0];

                        if (Session["User_ID"] == null)
                        {
                            Session["UserName"] = UserName;
                            Session["Password"] = PassWord;
                            Session["User_ID"] = drUsers["ID"].ToString();
                            Session["UserType_ID"] = drUsers["UserType_ID"].ToString();
                            DataLayer.OnlineUsers.UpdateRow_UserID_By_SessionID(
                                                                                 Session["User_ID"],
                                                                                 Session.SessionID);
                        }
                        if (!HttpContext.Current.User.Identity.IsAuthenticated)
                        {
                            FormsAuthentication.SetAuthCookie(drUsers["ID"].ToString(), true);
                        }
                    }
                }
            }
        }
    }
}

也是为了理解我的登录代码我正在使用RoleProvider如下:

  using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Web;
    using System.Web.Security;
    using System.Data;

    namespace NiceFileExplorer.Classes
    {
        public class NiceFileExplorerRoleProvider : RoleProvider
        {
            public override void AddUsersToRoles(string[] usernames, string[] roleNames)
            {
                throw new NotImplementedException();
            }

            public override string ApplicationName
            {
                get
                {
                    throw new NotImplementedException();
                }
                set
                {
                    throw new NotImplementedException();
                }
            }

            public override void CreateRole(string roleName)
            {
                throw new NotImplementedException();
            }

            public override bool DeleteRole(string roleName, bool throwOnPopulatedRole)
            {
                throw new NotImplementedException();
            }

            public override string[] FindUsersInRole(string roleName, string usernameToMatch)
            {
                throw new NotImplementedException();
            }

            public override string[] GetAllRoles()
            {
                throw new NotImplementedException();
            }

            //public override string[] GetRolesForUser(string username)
            public override string[] GetRolesForUser(string User_ID)
            {
                string[] UserTypes = new string[1];
                DataSet dsUser = DataLayer.Users.SelectRowWithUserTypeInfo(int.Parse(User_ID));
                if (dsUser.Tables["Users"].Rows.Count > 0)
                {
                    DataRow drUser = dsUser.Tables["Users"].Rows[0];
                    UserTypes[0] = drUser["Name"].ToString();
                }
                if (User_ID == "-255")
                {
                    UserTypes[0] = "Administrators";
                }
                return UserTypes;
            }

            public override string[] GetUsersInRole(string roleName)
            {
                throw new NotImplementedException();
            }

            public override bool IsUserInRole(string username, string roleName)
            {
                throw new NotImplementedException();
            }

            public override void RemoveUsersFromRoles(string[] usernames, string[] roleNames)
            {
                throw new NotImplementedException();
            }

            public override bool RoleExists(string roleName)
            {
                throw new NotImplementedException();
            }
        }

}

有时我有以下错误:

System.Web.HttpException:在发送HTTP标头后,服务器无法修改cookie.

System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.Web.HttpException (0x80004005): Server cannot modify cookies after HTTP headers have been sent.
   at System.Web.HttpCookieCollection.Add(HttpCookie cookie)
   at System.Web.Security.FormsAuthentication.SetAuthCookie(String userName, Boolean createPersistentCookie, String strCookiePath)
   at NiceFileExplorer.en.Site1.Page_Load(Object sender, EventArgs e)
   at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

看来问题出在以下几行:

FormsAuthentication.SetAuthCookie(drUsers ["ID"].ToString(),true);

这个错误意味着什么,我怎么能阻止它？

Answer 1

"System.Web.HttpException:服务器无法在发送HTTP标头后修改cookie."

该错误表示您在http响应完成后尝试修改cookie.

我认为问题是您在执行FormsAuthentication.SignOut()后尝试修改cookie.

根据MSDN,这是调用SignOut()方法时发生的情况

调用SignOut方法时,通过调用Redirect方法并将endResponse参数设置为false来重定向到应用程序的登录页面.在当前页面执行完毕之前,重定向不会发生,因此可以运行其他代码.如果代码不包含显式重定向到另一个页面,则会将用户重定向到应用程序配置文件中配置的登录页面.

所以你试图在重定向发生后修改cookie.您可以通过在重定向之前设置cookie值来避免此错误.