Mastering Resin

JSTL and JSP-EL Support

JSTL is a specification for a library of tags that provide a collection of common functionality to Web designers using JSP The JSTL specification can be found at http://java.sun.com/products/jsp/jstl/. The library was developed Some of the functionality provided in the tag library is:

• Core functions (e.g., session tracking, runtime conditions, looping, and importing content)

• XML processing

• Internationalization

• Database Access

The URIs for each type of functionality in the library are shown in Table 3.5.

The Resin 3.x server line supports the JSTL specification. With JSTL, we can do things like:

<c:if test="${!empty cookie.userName}"> Welcome back <c:out value="${cookie.userName.value}" /> </c:if>

Another important advance in the Resin 3.x server line is support for JSP-EL. JSP-EL is a simple language for accessing data in a JSP page. With JSP-EL, information can be stored in places like a pageContext or a request. For example:

<% boolean newUser = true; pageContext.setAttribute("userStatus", new Boolean(newUser)); %>

The stored variable can then be used later in the page:

<c:if test="${userStatus}"> User is new </c:if>

In the spirit of JSTL, Resin includes support for tag files as defined in JSP 2.0. For example, we might have a tag file defined as:

<%@ attribute name="a" type="java.lang.String" required="true" %> A sample tag: ${a}

The tag file should be used in a JSP file:

<%@ taglib prefix="x" tagdir="WEB-INF/tags" %> <X:test a="Test 1"/>