jsp Creating custom tag libraries using JSP 2.0(Without java classes) A basic example of using a custom tag without any Java code

Example

In order to create an use a custome tag,we need to follow couple of steps:

1. Create a tag file,defining the attributes used by it and any variables which will be used by the tag

   a. The attributes need to have a name,their type and and required field with a boolean value

   b. The variables will be defined with a name along with a certain scope-

   NESTED(Available in tag body),

   AT_BEGIN(Within tag till end of scope) and

   AT_END(From end of tag till end of scope)

       <%@ attribute name="name" required="true" type="java.lang.String" description="Name of User"  %>
       <%@ attribute name="role" required="true" type="java.lang.String" description="Role of User" %>
       <%@ variable name-given="passBack" scope="AT_BEGIN"%>
       <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
   
       <h1>${name}</h1>
       <h2>${role}</h2>
       
       <%String backToCaller="Back to caller";%>
       <c:set var="passBack" value="Pass back successful"/>
   

2. Define the entry to import tag,where tagdir will be directory containing tag file with .tag extension

   <%@ taglib prefix="tags" tagdir="/WEB-INF/tags" %>
   

3. Finally use the tag,passing the required attributes,as per tag definition. Here customTag is the name of the tag file,along with prefix as defined

   <tags:customTag name="Hello Tag!!" role="I am the boss here"/>
   

4. The variable set from tag can be retrieved in the caller jsp using expression language

   Hello ${passBack}