Getting a Request Parameter Using JSTL in a JSP Page

When using the JSTL’s expression language (see Enabling the JSTL Expression Language in a JSP Page), the request parameters are made available in the implicit object param. This example demonstrates how to include the value of a request parameter from the query string or posted data in the generated output:

<%-- Declare the core library --%>
<%@ taglib uri="/WEB-INF/tld/c.tld" prefix="c" %>

<c:choose>
    <c:when test="${empty param.name}">
        Please enter your name.
    </c:when>
    <c:otherwise>
        Hello <b><c:out value="${param.name}" /></b>!
    </c:otherwise>
</c:choose>

If the page was accessed with the URL:

http://hostname.com/mywebapp/mypage.jsp?name=UserName

the resulting output would be:
Hello UserName!