example: public class: ControllerServlet

example
public class: ControllerServlet [javadoc | source]

java.lang.Object
   javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
         example.ControllerServlet

All Implemented Interfaces:
Serializable, Servlet, ServletConfig

Direct Known Subclasses:
GuestbookServlet

This is very very primitive MVC Controller servlet base class, based on example 1. The application specific controller servlet should extend this class.
Method from example.ControllerServlet Summary:
doGet, doPost, init
Methods from javax.servlet.http.HttpServlet:
service
Methods from javax.servlet.GenericServlet:
destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log, service
Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Method from example.ControllerServlet Detail:

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException
{ // Choose action method String action = req.getServletPath(); if (action == null) action = "index"; if (action.startsWith("/")) action = action.substring(1); if (action.lastIndexOf(".") != -1) { action = action.substring(0, action.lastIndexOf(".")); } Method actionMethod; try { actionMethod = getClass().getMethod(action + "Action", new Class[]{HttpServletRequest.class, Page.class}); } catch (NoSuchMethodException e) { throw new ServletException("Unknown action: " + action); } // Set the request charset to the same as the output charset, // because HTML forms normally send parameters encoded with that. req.setCharacterEncoding(cfg.getOutputEncoding()); // Call the action method Page page = new Page(); try { actionMethod.invoke(this, new Object[]{req, page}); } catch (IllegalAccessException e) { throw new ServletException(e); } catch (InvocationTargetException e) { throw new ServletException(e.getTargetException()); } if (page.getTemplate() != null) { // show a page with a template // Get the template object Template t = cfg.getTemplate(page.getTemplate()); // Prepare the HTTP response: // - Set the MIME-type and the charset of the output. // Note that the charset should be in sync with the output_encoding setting. resp.setContentType("text/html; charset=" + cfg.getOutputEncoding()); // - Prevent browser or proxy caching the page. // Note that you should use it only for development and for interactive // pages, as it significantly slows down the Web site. resp.setHeader("Cache-Control", "no-store, no-cache, must-revalidate, " + "post-check=0, pre-check=0"); resp.setHeader("Pragma", "no-cache"); resp.setHeader("Expires", "Thu, 01 Dec 1994 00:00:00 GMT"); Writer out = resp.getWriter(); // Merge the data-model and the template try { t.process(page.getRoot(), out); } catch (TemplateException e) { throw new ServletException( "Error while processing FreeMarker template", e); } } else if (page.getForward() != null) { // forward request RequestDispatcher rd = req.getRequestDispatcher(page.getForward()); rd.forward(req, resp); } else { throw new ServletException("The action didn't specified a command."); } }
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException
{ doGet(req, resp); }
public void init()
{ // Initialize the FreeMarker configuration; // - Create a configuration instance cfg = new Configuration(); // - Templates are stoted in the WEB-INF/templates directory of the Web app. cfg.setServletContextForTemplateLoading( getServletContext(), "WEB-INF/templates"); // - Set update dealy to 0 for now, to ease debugging and testing. // Higher value should be used in production environment. cfg.setTemplateUpdateDelay(0); // - Set an error handler that prints errors so they are readable with // a HTML browser. cfg.setTemplateExceptionHandler( TemplateExceptionHandler.HTML_DEBUG_HANDLER); // - Use beans wrapper (recommmended for most applications) cfg.setObjectWrapper(ObjectWrapper.BEANS_WRAPPER); // - Set the default charset of the template files cfg.setDefaultEncoding("ISO-8859-1"); // - Set the charset of the output. This is actually just a hint, that // templates may require for URL encoding and for generating META element // that uses http-equiv="Content-type". cfg.setOutputEncoding("UTF-8"); // - Set the default locale cfg.setLocale(Locale.US); }