Request Lifecycle
When a container receives a request, it passes that request to the Stripes filter. The Stripes filter then uses its stored configuration information to select the Locale for the request (Stripes stores the configuration information, which is not transparent you). The Stripes filter then wraps the HttpServletRequest with a StripesRequestWrapper. If the request is for a JSP page, the control directly flows to the JSP page and if it is for an action event, it is passed to the Stripes DispatcherServlet for further processing.
The DispatcherServlet uses the ActionBeanContextFactory to create the ActionBeanContext object. This is used to access variables stored in the session, request, and response contexts. The DispatcherServlet then fetches the ActionResolver to resolve the action bean associated with the request. The ActionResolver then creates a instance of the ActionBean and adds it to the scope specified under the key "actionBean". If no scope is specified, the bean is added to the request scope.
This is helpful when you need to identify the current action or the last executed action. The DispatcherServlet uses the ActionResolver to determine the method to be executed based on the event name. If no event name is present, the default handler method is executed. It's good practice to have a default handler method specified in the ActionBean, as it can take care of cases where the user hits the enter button to submit a form.
The DispatcherServlet next tries to perform validations on the form as specified in the ActionBean (validations will be explained further in a moment). Once the validation is complete, the DispatcherServlet executes the specific handler method and returns a Resolution object. The DispatcherServlet then calls the execute method to complete the request.
The Resolution object decides what needs to be done next after the ActionBean is executed. Depending on the type there are four options:
- Forward Resolution: Uses a server side forward directive to forward the user to another path in the same application.
- Redirect Resolution: Uses a client side redirect the user to another path in the same Web application or another Web application on the Web.
- Streaming Resolution: This is used to stream content back to the user in the form of a stream. The stream could be a PDF document, an image or any file that can be downloaded.
- JavaScript Resolution: This will convert a Java object into JavaScript objects and arrays and send it back to the client.
Struts and Stripes Compared
It's time to compare Struts with Stripes. If you're familiar with Struts, you'll find it easy to switch from Struts to Stripes because Stripes follows a similar syntax and requires less configuration work than Struts. One of the major problems with Struts is managing the various configuration files like the Struts config, tiles definition, etc. If you've worked on a large application with a lot of collaborators, you understand the frustration of merging changes in the Struts config file and unit testing the Web components. The Stripes framework makes it easy to manage the configuration files by getting rid of them altogether and replacing them with annotations in the action bean.
To help you compare Struts and Stripes, this article includes an example survey application developed both in Stripes and Struts. The contrast between the two examples illustrates both the differences and the common features of both these frameworks.
You'll also become familiar with some of Stripes' innovative features, including Wizard Forms and nested validations. You can also learn how to use annotations and the <stripes:layout-definition>, <stripes:layout-component>, and <stripes:layout-render> tags in developing reusable layouts.
To build and deploy the application, use the accompanying Ant task, ant deploywar. After the application is deployed, start your application server and navigate to http://<servername:port>/stripes-survey.
To run the application, build and deploy the application using ant deploywar and navigate to http://<servername:port>/stripes-hello. Enter a name and submit. You should see the "hello" message.
Here are the files:
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