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| <%@ 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 Lanaguage. 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>${fn:escapeXml(param["foo"])} </td> |
| </tr> |
| <tr> |
| <td>\${header["host"]}</td> |
| <td>${header["host"]}</td> |
| </tr> |
| <tr> |
| <td>\${header["accept"]}</td> |
| <td>${header["accept"]}</td> |
| </tr> |
| <tr> |
| <td>\${header["user-agent"]}</td> |
| <td>${header["user-agent"]}</td> |
| </tr> |
| </table> |
| </code> |
| </blockquote> |
| </body> |
| </html> |