<%@page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %> <html> <head> <title>JSP 2.0 Expression Language - Implicit Objects</title> </head> <body> <h1>JSP 2.0 Expression Language - Implicit Objects</h1> <hr> This example illustrates some of the implicit objects available in the Expression Language. The following implicit objects are available (not all illustrated here): <ul> <li>pageContext - the PageContext object</li> <li>pageScope - a Map that maps page-scoped attribute names to their values</li> <li>requestScope - a Map that maps request-scoped attribute names to their values</li> <li>sessionScope - a Map that maps session-scoped attribute names to their values</li> <li>applicationScope - a Map that maps application-scoped attribute names to their values</li> <li>param - a Map that maps parameter names to a single String parameter value</li> <li>paramValues - a Map that maps parameter names to a String[] of all values for that parameter</li> <li>header - a Map that maps header names to a single String header value</li> <li>headerValues - a Map that maps header names to a String[] of all values for that header</li> <li>initParam - a Map that maps context initialization parameter names to their String parameter value</li> <li>cookie - a Map that maps cookie names to a single Cookie object.</li> </ul> <blockquote> <u><b>Change Parameter</b></u> <form action="implicit-objects.jsp" method="GET"> foo = <input type="text" name="foo" value="${fn:escapeXml(param["foo"])}"> <input type="submit"> </form> <br> <code> <table border="1"> <thead> <td><b>EL Expression</b></td> <td><b>Result</b></td> </thead> <tr> <td>\${param.foo}</td> <td>${fn:escapeXml(param["foo"])} </td> </tr> <tr> <td>\${param["foo"]}</td> <td>${fn:escapeXml(param["foo"])} </td> </tr> <tr> <td>\${header["host"]}</td> <td>${fn:escapeXml(header["host"])} </td> </tr> <tr> <td>\${header["accept"]}</td> <td>${fn:escapeXml(header["accept"])} </td> </tr> <tr> <td>\${header["user-agent"]}</td> <td>${fn:escapeXml(header["user-agent"])} </td> </tr> </table> </code> </blockquote> </body> </html>