.net主站和二级域名下实现session共享

     public class CrossDomainCookie : IHttpModule
     {
         private string m_RootDomain = string.Empty;

         #region IHttpModule Members

         public void Dispose()
         {

         }

         public void Init(HttpApplication context)
         {
             m_RootDomain = ConfigurationManager.AppSettings["RootDomain"];

             Type stateServerSessionProvider = typeof(HttpSessionState).Assembly.GetType("System.Web.SessionState.OutOfProcSessionStateStore");
             FieldInfo uriField = stateServerSessionProvider.GetField("s_uribase", BindingFlags.Static | BindingFlags.NonPublic);

             if (uriField == null)
                 throw new ArgumentException("UriField was not found");

             uriField.SetValue(null, m_RootDomain);

             context.EndRequest += new System.EventHandler(context_EndRequest);
         }

         void context_EndRequest(object sender, System.EventArgs e)
         {
             HttpApplication app = sender as HttpApplication;

             for (int i = ; i < app.Context.Response.Cookies.Count; i++)
             {
                 app.Context.Response.Cookies[i].Domain = m_RootDomain;
             }
         }

         #endregion
     }

config里面配置：（注意两个站点都要配置）

 <configuration>
   <appSettings>
     <add key="RootDomain" value=".session.com"/>
   </appSettings>
   <connectionStrings/>
   <system.web>
     <machineKey decryptionKey="FD69B2EB9A11E3063518F1932E314E4AA1577BF0B824F369" validationKey="5F32295C31223A362286DD5777916FCD0FD2A8EF882783FD3E29AB1FCDFE931F8FA45A8E468B7A40269E50A748778CBB8DB2262D44A86BBCEA96DCA46CBC05C3" validation="SHA1" decryption="Auto"/>
     <sessionState cookieless="false" timeout="" mode="StateServer" stateConnectionString="tcpip=127.0.0.1:42424"/>
     <httpModules>
       <add name="CrossDomainCookieModule" type="WebLibrary.CrossDomainCookie, WebLibrary"/>
     </httpModules>
     <pages controlRenderingCompatibilityVersion="3.5" clientIDMode="AutoID"/>
   </system.web>
   <!--
         The system.webServer section is required for running ASP.NET AJAX under Internet
         Information Services 7.0.  It is not necessary for previous version of IIS.
     -->
   <system.webServer>
     <modules>
       <add name="CrossDomainCookieModule" preCondition="managedHandler" type="WebLibrary.CrossDomainCookie, WebLibrary"/>
     </modules>
   </system.webServer>
 </configuration>