The JSP expression language defines a set of implicit objects:
■ pageContext: The context for the JSP page. Provides access to various objects including:
■ servletContext: The context for the JSP page’s servlet and any web components contained in the same application. See “Accessing the Web Context” on page 124.
■ session: The session object for the client. See “Maintaining Client State” on page 125.
■ request: The request triggering the execution of the JSP page. See “Getting Information from Requests” on page 110.
■ response: The response returned by the JSP page. See “Constructing Responses” on page 112.
■ In addition, several implicit objects are available that allow easy access to the following objects:
■ param:Maps a request parameter name to a single value
■ paramValues:Maps a request parameter name to an array of values
■ header:Maps a request header name to a single value
■ headerValues:Maps a request header name to an array of values
■ cookie:Maps a cookie name to a single cookie
■ initParam:Maps a context initialization parameter name to a single value
■ Finally, there are objects that allow access to the various scoped variables described in “Using Scope Objects” on page 105.
■ pageScope:Maps page-scoped variable names to their values
■ requestScope:Maps request-scoped variable names to their values
■ sessionScope:Maps session-scoped variable names to their values
■ applicationScope:Maps application-scoped variable names to their values