HttpContext.Current.Session为null

Question

我在类库中有一个带有自定义Cache对象的WebSite.所有项目都运行.NET 3.5.我想将此类转换为使用会话状态而不是缓存,以便在我的应用程序回收时保留状态服务器中的状态.但是,当我从Global.asax文件访问方法时,此代码抛出"HttpContext.Current.Session为null"的异常.我这样叫这个班:

Customer customer = CustomerCache.Instance.GetCustomer(authTicket.UserData);

为什么对象总是为空？

public class CustomerCache: System.Web.SessionState.IRequiresSessionState
{
    private static CustomerCache m_instance;

    private static Cache m_cache = HttpContext.Current.Cache;

    private CustomerCache()
    {
    }

    public static CustomerCache Instance
    {
        get
        {
            if ( m_instance == null )
                m_instance = new CustomerCache();

            return m_instance;
        }
    }

    public void AddCustomer( string key, Customer customer )
    {
        HttpContext.Current.Session[key] = customer;

        m_cache.Insert( key, customer, null, Cache.NoAbsoluteExpiration, new TimeSpan( 0, 20, 0 ), CacheItemPriority.NotRemovable, null );
    }

    public Customer GetCustomer( string key )
    {
        object test = HttpContext.Current.Session[ key ];

        return m_cache[ key ] as Customer;
    }
}

正如您所看到的,我已经尝试将IRequiresSessionState添加到类中,但这并没有什么区别.

干杯Jens

Answer 1

它并不是真正将State包含在你的类中,而是你在Global.asax中调用它.会话不适用于所有方法.

一个工作的例子是:

using System.Web.SessionState;

// ...

protected void Application_PreRequestHandlerExecute(object sender, EventArgs e)
    {
        if (Context.Handler is IRequiresSessionState || Context.Handler is IReadOnlySessionState)
        {
            HttpContext context = HttpContext.Current;
            // Your Methods
        }
    }

它在例如Application_Start中不起作用