重启后，Spring没有将tomcat持久会话恢复到会话注册表?

I'm using Tomcat 6.2 and Spring MVC 2.5. I've noticed that, whilst a user is logged in I can restart Tomcat and the user is able to continue browsing without re-authenticating. This appears to be coming from Tomcat's ability to persist sessions across restarts.I'm using Tomcat 6.2 and Spring MVC 2.5. I've n