,ch14.9433  Page 471  Monday, February 14, 2005  12:55 PM


Solution


Integrate the Velocity template engine into your Struts application, replacing your


JSP pages with Velocity templates.


Discussion


The Velocity template engine (http://jakarta.apache.org/velocity) can create any kind


of textual document by merging Java objects with a template. The template docu 


ment contains special markup that Velocity parses and replaces with values from


Java objects stored in a template context.


When you use Velocity with Struts, instead of forwarding to JSP pages, you forward


to a Velocity template. The Velocity servlet services the request, processing the tem 


plate through the Velocity template engine and returning the generated HTML as the


response.


Here's an action, adapted from the Struts MailReader example, that forwards to a


Velocity template to display the  Welcome  page:




           type="org.apache.struts.webapp.example.WelcomeAction">


    


    




To use Velocity with Struts, you'll need to download the Velocity distribution from


http://jakarta.apache.org/velocity. You also need to download the VelocityTools from


http://jakarta.apache.org/velocity/tools/. VelocityTools includes helper classes that


allow you to reference Struts managed objects such as the action form and message


resources. From the Velocity distribution, copy the velocity 1.4.jar and the velocity 


dep 1.4.jar from the Velocity distribution directory to your application's WEB INF/


lib directory. For the VelocityTools /lib directory, copy the velocity tools 1.1.jar,


velocity tools generic 1.1.jar, velocity tools view 1.1.jar to your application's WEB 


INF/lib directory.


Next, declare the Velocity view servlet and servlet mapping in your web.xml file. Tra 


ditionally, the .vm extension is used for Velocity templates. Example 14 26 shows


the portion of a web.xml file that configure the Velocity servlet.


Example 14 26. VelocityViewServlet declaration and mapping






    velocity


    


        org.apache.velocity.tools.view.servlet.VelocityViewServlet


    


Integrating Struts and Velocity | 471


This is the Title of the Book, eMatter Edition


Copyright   2005 O'Reilly & Associates, Inc. All rights reserved.








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