Five large domain objects built-in objects of JSP 9

Objects are four domains:
the pageContext (PageContextImpl class) within the current range of the effective jsp page
request (the HttpServletRequest class) the request is a valid
session (the HttpSession class) within the effective range of a session (open a browser to access the server, until the browser is closed)
file application They are valid within (the ServletContext class) the entire web project range (as long as the web project is not stopped, in the data)


domain object is the same as the access target data Map. Like four domain functional objects. Except that they access range of the data.
Although four domain object can access the data. They are used in priority.
Four field when in use, are the priority order of them from small to large range.
pageContext ==== >>> request ==== >>> session ==== >>> application