ex6_18.txt

j2ee core design patterns

Example 6.18 Front Controller
public class FrontController extends HttpServlet {
  private ApplicationController applicationController;

  public void init(ServletConfig servletConfig) throws
      ServletException{

    super.init(servletConfig);

    // Initialize Request Processing(Stateless) Components
    applicationController = new ApplicationControllerImpl();
    applicationController.initialize();
  }

  // called from doGet and doPost
  protected void process(HttpServletRequest request,
      HttpServletResponse response) throws java.io.IOException {

    // Create RequestContext based on request type
    RequestContextFactory requestContextFactory =
        RequestContextFactory.getInstance();
    RequestContext requestContext = 
        requestContextFactory.createRequestContext(request);

    // Request Processing
    ResponseContext responseContext =
        applicationController.handleRequest(requestContext);

    // View Management - Navigate and Dispatch to appropriate view
    Dispatcher dispatcher = new Dispatcher(request, response);
    responseContext.setDispatcher(dispatcher);
    applicationController.handleResponse(requestContext,
        responseContext);
  }
  . . .
}