Windows Phone 7 Mango сохраняет состояние CookieContainer

Вы не можете получить доступ к закрытым членам за пределами вашей сборки в WP7, даже с Reflection. Это мера безопасности, гарантирующая, что вы не сможете вызывать внутренние системные API.

Похоже, вам может не повезти.

Я написал CookieSerializer, специально предназначенный для решения этой проблемы. Сериализатор вставлен ниже. Рабочий проект и сценарий можно найти на сайте CodePlex.

public static class CookieSerializer
{
    /// <summary>
    /// Serializes the cookie collection to the stream.
    /// </summary>
    /// <param name="cookies">You can obtain the collection through your <see cref="CookieAwareWebClient">WebClient</see>'s <code>CookieContainer.GetCookies(Uri)</code>-method.</param>
    /// <param name="address">The <see cref="Uri">Uri</see> that produced the cookies</param>
    /// <param name="stream">The stream to which to serialize</param>
    public static void Serialize(CookieCollection cookies, Uri address, Stream stream)
    {
        using (var writer = new StreamWriter(stream))
        {
            for (var enumerator = cookies.GetEnumerator(); enumerator.MoveNext();)
            {
                var cookie = enumerator.Current as Cookie;
                if (cookie == null) continue;
                writer.WriteLine(address.AbsoluteUri);
                writer.WriteLine(cookie.Comment);
                writer.WriteLine(cookie.CommentUri == null ? null : cookie.CommentUri.AbsoluteUri);
                writer.WriteLine(cookie.Discard);
                writer.WriteLine(cookie.Domain);
                writer.WriteLine(cookie.Expired);
                writer.WriteLine(cookie.Expires);
                writer.WriteLine(cookie.HttpOnly);
                writer.WriteLine(cookie.Name);
                writer.WriteLine(cookie.Path);
                writer.WriteLine(cookie.Port);
                writer.WriteLine(cookie.Secure);
                writer.WriteLine(cookie.Value);
                writer.WriteLine(cookie.Version);
            }
        }
    }

    /// <summary>
    /// Deserializes <see cref="Cookie">Cookie</see>s from the <see cref="Stream">Stream</see>, 
    /// filling the <see cref="CookieContainer">CookieContainer</see>.
    /// </summary>
    /// <param name="stream">Stream to read</param>
    /// <param name="container">Container to fill</param>
    public static void Deserialize(Stream stream, CookieContainer container)
    {
        using (var reader = new StreamReader(stream))
        {
            while (!reader.EndOfStream)
            {
                var uri = Read(reader, absoluteUri => new Uri(absoluteUri, UriKind.Absolute));
                var cookie = new Cookie();
                cookie.Comment = Read(reader, comment => comment);
                cookie.CommentUri = Read(reader, absoluteUri => new Uri(absoluteUri, UriKind.Absolute));
                cookie.Discard = Read(reader, bool.Parse);
                cookie.Domain = Read(reader, domain => domain);
                cookie.Expired = Read(reader, bool.Parse);
                cookie.Expires = Read(reader, DateTime.Parse);
                cookie.HttpOnly = Read(reader, bool.Parse);
                cookie.Name = Read(reader, name => name);
                cookie.Path = Read(reader, path => path);
                cookie.Port = Read(reader, port => port);
                cookie.Secure = Read(reader, bool.Parse);
                cookie.Value = Read(reader, value => value);
                cookie.Version = Read(reader, int.Parse);
                container.Add(uri, cookie);
            }
        }
    }

    /// <summary>
    /// Reads a value (line) from the serialized file, translating the string value into a specific type
    /// </summary>
    /// <typeparam name="T">Target type</typeparam>
    /// <param name="reader">Input stream</param>
    /// <param name="translator">Translation function - translate the read value into 
    /// <typeparamref name="T"/> if the read value is not <code>null</code>.
    /// <remarks>If the target type is <see cref="Uri">Uri</see> , the value is considered <code>null</code> if it's an empty string.</remarks> </param>
    /// <param name="defaultValue">The default value to return if the read value is <code>null</code>.
    /// <remarks>The translation function will not be called for null values.</remarks></param>
    /// <returns></returns>
    private static T Read<T>(TextReader reader, Func<string, T> translator, T defaultValue = default(T))
    {
        var value = reader.ReadLine();
        if (value == null)
            return defaultValue;
        if (typeof(T) == typeof(Uri) && String.IsNullOrEmpty(value))
            return defaultValue;
        return translator(value);
    }
}