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Benefits of MVC

  • Data assembled by controllers can be presented by different views
  • Site can be reskinned without touching the application logic
  • Application logic can be re-factored without touching the presentation
  • UI and Application teams can work with maximum independence

What is FreeMarker

  • An all-purpose Java template engine for generating text output based on templates
  • Not specifically designed to generate web pages, so text generation is independent of the servlet application architecture

FreeMarker Features

  • Separation of application and presentation logic is enforced through:
    • Syntactic limitations of the template language
    • Exposure settings on the template data
  • Only FTL is allowed in templates
    • No Java code
  • Template language
    • Clean, simple, and consistent
    • Just powerful enough
      • Loops, conditionals, local variables, macros, object property access, convenient built-in functions
  • String capture
    • Controller can use the engine to generate a string without relinquishing control of the request
  • Flexible and powerful API
  • Thorough documentation
    • API documentation
    • Template developer documentation
  • Active user mailing list

Two ways to use FreeMarker in VIVO

  • Generate an entire page in FreeMarker
    • This is the direction the application is moving in; transition is still incomplete
  • Generate a string for use outside a FreeMarker page
    • In the transition from JSPs, generate page headers, footers, menus, etc. using the same FreeMarker templates used in generating whole pages
    • Email messages
    • Ajax responses

Using FreeMarker

public class AboutController extends FreemarkerHttpServlet {
	
	private static final String TEMPLATE_DEFAULT = "about.ftl";
    
    @Override
    protected ResponseValues processRequest(VitroRequest vreq) {
        ApplicationBean application = vreq.getAppBean();
        
        Map<String, Object> body = new HashMap<String, Object>();
        body.put("aboutText", application.getAboutText());
        body.put("acknowledgeText", application.getAcknowledgeText());
        
        return new TemplateResponseValues(TEMPLATE_DEFAULT, body);
    }

    @Override
    protected String getTitle(String siteName, VitroRequest vreq) {
    	return "About " + siteName;
    }

}
  • processRequest() can return a different type of object to trigger a forward, redirect, or error
  • Override FreemarkerHttpServlet.doGet()
    • Use methods defined in FreemarkerHttpServlet as needed to generate a page

Resources

Tools