（1）application
    实际类型：org.apache.catalina.core.ApplicationContextFacade
    ApplicationContextFacade实现接口javax.servlet.ServletContext

（2）page
    实际类型：org.apache.jsp.index_jsp
    index_jsp继承类org.apache.jasper.runtime.HttpJspBase
    HttpJspBase继承类javax.servlet.http.HttpServlet

（3）config
    实际类型：org.apache.catalina.core.StandardWrapperFacade
    StandardWrapperFacade实现接口javax.servlet.ServletConfig

（4）request
    实际类型：org.apache.catalina.connector.RequestFacade
    RequestFacade 实现接口javax.servlet.http.HttpServletRequest

（5）response
    实际类型：org.apache.catalina.connector.ResponseFacade 
    ResponseFacade实现接口javax.servlet.http.HttpServletRequest

（6）out
    实际类型：org.apache.jasper.runtime.JspWriterImpl
    JspWriterImpl继承类javax.servlet.jsp.JspWriter

（7）session
    实际类型：org.apache.catalina.session.StandardSessionFacade
    StandardSessionFacade实现接口javax.servlet.http.HttpSession

（8）pageContext
    实际类型：org.apache.jasper.runtime.PageContextImpl 
    PageContextImpl继承类javax.servlet.jsp.PageContext

（9）exception: