ex6_40.txt

j2ee core design patterns

Example 6.40 ApplicationController Implementation
public class RequestProcessor {
  public void process(HttpServletRequest request,
      HttpServletResponse response)
      throws IOException, ServletException {

    // Identify Command Id (path) from request object
    String path = processPath(request, response);
    .  .  .
    // Identify Command Map based on Command Id
    ActionMapping mapping = processMapping(request, response, path);
    if (mapping == null) {
      return;
    }

    // Authorize user based on Command-Map security settings
    if (!processRoles(request, response, mapping)) {
      return;
    }

    // Identify Command Context Object from CommandMap
    ActionForm form = processActionForm(request, response, mapping);

    // Auto-populate Context Object from request 
    processPopulate(request, response, form, mapping);

    // Validate Context Object request state
    if (!processValidate(request, response, form, mapping)) {
      return;
    }
    // Create or acquire the Command instance to process this request
    Action action = processActionCreate(request, response, mapping);
    if (action == null) {
      return;
    }
    .  .  .

    // Execute Command and get ViewHandle
    ActionForward forward =  action.execute(mapping, form, request,
        response);

    // Dispatch to appropriate View using ViewHandle
    processActionForward(request, response, forward);

  }


  // Handle Response
  protected void processActionForward(HttpServletRequest request,
      HttpServletResponse response, ActionForward forward)
      throws IOException, ServletException {
    .  .  .
    // Dispatch to View
    RequestDispatcher rd =
        getServletContext().getRequestDispatcher(uri);
    rd.forward(request, response);
    .  .  .

  }
}