JSP and JSTL Tutorials - Tutorial Addendum - JSTL - Syntax and Announcement Accent

This affiliate explains:

    

    
• Basics on JSTL syntax.
  
      



    
• Basics on Announcement Language.
  
      



    
• Literal data and called variables.
  
      



    
• Basic operators and operations.
  
      



    
• Accessing accumulating elements and item properties.
  
      



    
• ExpExample.jsp - Announcement examples JSP page.
  
      



    
• pageContext attributes and JSTL top akin identifiers.
  
      



    

JSTL Syntax

    

JSTL syntax is actual simple. JSTL allows you to address tags in JSP pages.

    

Each tag is infact alleged an action. Every activity haveto be accounting as an XML element.

    

The syntax of an JSTL activity XML aspect is something like these:

    

    
<p:tag attribute="text_only"/>

    
<p:tag>

    
   xml_body

    
</p:tag>

    
<p:tag attribute="text_only">

    
   xml_body

    
</p:tag>

    
<p:tag attribute="${expression}">

    
   xml_body

    
</p:tag>

    
<p:tag attribute="text${expression}text${express}..." ...>

    
   xml_body

    
</p:tag>

    

As you can see, there are a amount variations in the syntax:

    

    
• An activity can be an abandoned or non-empty XML element.
  
      



    
• An activity can accept zero, one, or some attributes.
  
      



    
• Attribute ethics can be argument only, or alloyed with expressions.
  
      



    
• An accurate is consistently accounting in the architecture of ${expression}.
  
      



    

The expressions haveto be accounting by folowing rules authentic by the announcement language.

    

Examples of JSTL actions:

    

 

    
<c:out value="Hello world!"/>

    
<c:if test="${1+1==2}">

    
   Consistently true.

    
</c:if>

    
<c:set var="message" value="Hello world!"/>

    
<c:out value="${message}"/>

    

Expression Language

    

Since announcement will be acclimated in alotof of the JSTL actions, let s attending at the

    

express accent afore alone JSTL actions.

    

JSTL announcement accent is aggressive by both ECMAScript and XPath announcement language.

    

It is simple, and acknowledging the afterward features:

    

    
• Literal data and called variables.
  
      



    
• Logical, relational and addition operations.
  
      



    
• A set of absolute objects.
  
      



    
• Nested backdrop and accessors to collections.
  
      



    

Examples of JSTL expressions:

    

 

    
<c:out value="${1+1==2}"/>

    
<c:out value="${1+1}"/> 

    
<c:out value="${1/3}"/> 

    
<c:out value="${1.0/3.0}"/> 

    
<c:out value="${message}"/>

    
<c:out value="${pageContext.request.class.name}"/>

    
<c:out value="${pageContext.request.method}"/>

    
<c:out value="${pageContext.request.requestedSessionId}"/>

    
<c:out value="${pageContext.request.cookies[0].name}"/>

    
<c:out value="${quantity*price < 100.0 && country== USA }"/> 

    

Literal Data and Called Variables

    

As in all computer language, announcement starts with accurate data and variables.

    

JSTL announcement accent supports 5 types of accurate data:

    

    
• Boolean - true and false. Aforementioned as Java boolean.
  
      



    
• Integer - like 9999, -3, and 0. Aforementioned as Java long.
  
      



    
• Floating point amount - like, 1.0, 3.14159, and -1.0e-3. Aforementioned as Java double.
  
      



    
• String - like, USA , "USA", or s notes. Abutting to Java String.
  
      



    
• Null - null. Aforementioned as Java null.
  
      



    

(Continued on next part...)