VelocityHelper Class Reference

A facade class that simplifies using a custom Velocity engine from a servlet. More...

Collaboration diagram for VelocityHelper:

Public Member Functions
	VelocityHelper (ServletContext servletContext, HttpServletResponse response)
Context	getVelocityContext ()
void	renderXHTML (String templateName)
	Renders a template using the template variables put into the velocity context. More...

Private Member Functions
VelocityEngine	getVelocityEngine ()
VelocityEngine	createVelocityEngine ()

Private Attributes
final ServletContext	servletContext
final HttpServletResponse	response
final Context	velocityContext

Static Private Attributes
static final String	VELOCITY_ENGINE

Detailed Description

A facade class that simplifies using a custom Velocity engine from a servlet.

It encapsulates creation of the VelocityEngine instance, its storage in the servlet context, and the rendering of templates into the servlet response output stream.

Constructor & Destructor Documentation

VelocityHelper()

VelocityHelper	(	ServletContext	servletContext,
		HttpServletResponse	response
	)

                                                                                           {
                this.servletContext = servletContext;
                this.response = response;
                this.velocityContext = new VelocityContext();
        }

References VelocityHelper.response, and VelocityHelper.servletContext.

Member Function Documentation

createVelocityEngine()

VelocityEngine createVelocityEngine ( )

private

                                                      {
                try {
                        VelocityEngine result = new VelocityEngine();
                        result.setProperty("output.encoding", "utf-8");
                        result.setProperty("file.resource.loader.path", 
                                        servletContext.getRealPath("/") + "/WEB-INF/templates/");
                        result.setProperty("velocimacro.context.localscope", true);
                        
                        // Turn off Velocity logging
                        result.setProperty("runtime.log.logsystem.class", 
                                        "org.apache.velocity.runtime.log.NullLogSystem");
                        
                        // XML-escape *all* references inserted into templates
                        result.setProperty("eventhandler.referenceinsertion.class", EscapeXmlReference.class.getName());
                        
                        // Enable caching
                        result.setProperty("file.resource.loader.cache", true);
                        
                        result.init();
                        return result;
                } catch (Exception ex) {
                        throw new RuntimeException(ex);
                }
        }

References VelocityHelper.servletContext.

Referenced by VelocityHelper.getVelocityEngine().

getVelocityContext()

Context getVelocityContext

(

)

Returns

A receptacle for template variables

                                            {
                return velocityContext;
        }

References VelocityHelper.velocityContext.

getVelocityEngine()

VelocityEngine getVelocityEngine ( )

private

                                                   {
                synchronized (servletContext) {
                        if (servletContext.getAttribute(VELOCITY_ENGINE) == null) {
                                servletContext.setAttribute(VELOCITY_ENGINE, createVelocityEngine());
                        }
                        return (VelocityEngine) servletContext.getAttribute(VELOCITY_ENGINE);
                }
        }

References VelocityHelper.createVelocityEngine(), VelocityHelper.servletContext, and VelocityHelper.VELOCITY_ENGINE.

Referenced by VelocityHelper.renderXHTML().

renderXHTML()

void renderXHTML

(

String

templateName

)

Renders a template using the template variables put into the velocity context.

                                                     {
                response.addHeader("Content-Type", "text/html; charset=utf-8");
                response.addHeader("Cache-Control", "no-cache");
                response.addHeader("Pragma", "no-cache");
                try {
                        OutputStreamWriter writer = new OutputStreamWriter(response.getOutputStream(), "utf-8");
                        getVelocityEngine().mergeTemplate(templateName,"UTF-8", velocityContext, 
                                        writer);
                        writer.close();
                } catch (Exception ex) {
                        throw new RuntimeException(ex);
                }
        }

References VelocityHelper.getVelocityEngine(), VelocityHelper.response, and VelocityHelper.velocityContext.

Member Data Documentation

response

final HttpServletResponse response

private

Referenced by VelocityHelper.renderXHTML(), and VelocityHelper.VelocityHelper().

servletContext

final ServletContext servletContext

private

Referenced by VelocityHelper.createVelocityEngine(), VelocityHelper.getVelocityEngine(), and VelocityHelper.VelocityHelper().

VELOCITY_ENGINE

final String VELOCITY_ENGINE

staticprivate

Initial value:

= 
                VelocityHelper.class.getName() + ".VELOCITY_ENGINE"

Referenced by VelocityHelper.getVelocityEngine().

velocityContext

final Context velocityContext

private

Referenced by VelocityHelper.getVelocityContext(), and VelocityHelper.renderXHTML().