JSP 2.0 Expression Language - Implicit Objects

This example illustrates some of the implicit objects available in the Expression Language. The following implicit objects are available (not all illustrated here):

pageContext - the PageContext object
pageScope - a Map that maps page-scoped attribute names to their values
requestScope - a Map that maps request-scoped attribute names to their values
sessionScope - a Map that maps session-scoped attribute names to their values
applicationScope - a Map that maps application-scoped attribute names to their values
param - a Map that maps parameter names to a single String parameter value
paramValues - a Map that maps parameter names to a String[] of all values for that parameter
header - a Map that maps header names to a single String header value
headerValues - a Map that maps header names to a String[] of all values for that header
initParam - a Map that maps context initialization parameter names to their String parameter value
cookie - a Map that maps cookie names to a single Cookie object.

Change Parameter
foo =

EL Expression Result ${param.foo} bar ${param["foo"]} bar ${header["host"]} ckanstat.cm-lisboa.pt:80 ${header["accept"]} text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 ${header["user-agent"]} arquivo-web-crawler (compatible; heritrix/3.3.0-SNAPSHOT-2019-08-26T10:34:48Z +http://arquivo.pt)

EL Expression	Result
${param.foo}	bar
${param["foo"]}	bar
${header["host"]}	ckanstat.cm-lisboa.pt:80
${header["accept"]}	text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
${header["user-agent"]}	arquivo-web-crawler (compatible; heritrix/3.3.0-SNAPSHOT-2019-08-26T10:34:48Z +http://arquivo.pt)