JavaServer Pages, Second Edition

Variables

Variables are named references to data (objects), created by the application or made available implicitly by the EL. Application-specific variables can be created in many ways, for instance using the <jsp:useBean> action. They can also be created by custom actions or be passed to the JSP page by a servlet. Every object that is available in one of the JSP scopes can be used as an EL variable:

<c:out value="${aScopedVariable}" />

Implicit Variables

All information about a request and other data can be accessed through the EL implicit variables:

Variable name	Description
pageScope	A collection of all page scope variables (a java.util.Map).
requestScope	A collection of all request scope variables (a java.util.Map)
sessionScope	A collection of all session scope variables (a java.util.Map)
applicationScope	A collection of all application scope variables (a java.util.Map)
param	A collection of all request parameter values, as a single String value per parameter (a java.util.Map)
paramValues	A collection of all request parameter values, as a String array per parameter (a java.util.Map)
header	A collection of all request header values, as a single String value per header (a java.util.Map)
headerValues	A collection of all request header values, as a String array per header (a java.util.Map)
cookie	A collection of all request cookie values, as a single javax.servlet.http.Cookie value per cookie (a java.util.Map). See Appendix D for a list of properties ...