Im new to jsp and MVC. Im studying this application that registers a customer into the database and then searches for it. The files that Im creating are Customer.java, Customer.jsp, CustomerDAO.java, CustomerContrtoller.java, CustomerService.java, result.jsp and ConnectionManager.java. How does this follow the MVC model? How do I know what is the model, view and controller in this app?
The MVC applies as follows to Jsps:
The model is your Customer.java. This model is used by the Jsp to render Html. The Jsp is the view. The CustomerController is the controller. The controller handles actions, like clicks, of the user, prepares the model and sends it to the Jsp.
Your confusion comes from the CustomerDao, I think. You have to understand that MVC is a frontend pattern. The model used in MVC can be the same as the Dao from the database, but most of the time it's not. Just the interaction between the Jsp, the controller and the model displayed on the Jsp is part of the MVC concept.
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I am creating a spring boot server, and I would like the initial page (index.jsp) to be a datatable with information coming from the redis database. Anyone know how to do this with javascript or inside jsp pages?
First of all JSPs are outdated technology so I recommend you to go for thymeleaf which is a perfect choice with spring boot instead of JSP.
JAVA approach :
Just create a mapping with / base url and fetch Redis data using normal approach and use it in UI.
GetMapping("/")
public String index(){
//Fetch Redis data here add into model attributes
return "index";
}
JavaScript/inside JSP approach :
You can create a mapping method with some url like above and make an AJAX call on page load from the JSP page and get the JSON format data and use it.
Don't forget to put #ResponseBody annotation on top of the method which will return the data(JSON) instead of the page.
Refer call ajax to spring controller
as i understand MVC pattern as post MVC question
-
the Model is the part of the code that knows things
the View is the part of the code that shows the things the Model
knows
the Controller is the part of the code that gets commands from the
user and tells the View what to show and the Model what to know.
in spring-mvc we have DispatcherServlet which acts as controller gets command from client, also we have developer written controllers which serve commands and resolve the view and prepare Model for that view
in spring-mvc what exactly acts as controller DispatcherServlet or developer written controllers
Your #Controller annotated classes are your controllers. Think of the DispatcherServlet - as the name tells you - as dispatcher to your controllers.This is the same approach other MVC frameworks also choose (like Struts 2).
I have a quick question about how to use the Spring MVC.
I just started with it and i was used to have pages that always had their data loaded calling some controller that you setted ON THE PAGE.. calling some methods on controllers to load objects at the page at load time.
Is it the same in Spring MVC? Cuz what im seeing so far is that if you want to load a page with data, you always have to use a modelandview object which is loaded by a method that you must call before... and them you return the modelandview object with its destination to the view that you want.
What im trying to know is if there is a way that the page requests some data from the controller before it gets loaded... automatically...
Dont know if im making my self clear... thanks anyway for the help!
in spring mvc, using Controllers, it is always Request->Controller(populates model and chooses view)->Response.
you could use ajax to load data from any resource (even Controllers) or jsp:useBean to explicitly call some business logic or jsp:include to include a certain fragment or a custom jsp tag.
I also face the same situation.
check the below link for getting the data from the controller before view(JSP) load.
how to load the data into index page
I am developing my site in Spring MVC with Sitemesh.
Dynamic content is changed oon every page, Menu and Footer I can include in template definition. But there comes a problem. On every site below the dynamic content there should be a news list with loaded some news from my DB. I created my #Controller and it loads 5 latest news, but how to add this on my template? What request mapping should implement my news controller?
I don't kwow how Sitemesh works, but I solved problems like that by using interceptor:
create a class that extends : HandlerInterceptorAdapter
Override the method postHandle and populate the modelAndView Object like this :
modelAndView.addObject("newslist",myNewsList);
So you will have a variable $newslist injected into all your views.
Don't forget to declare bean in your mvc-congig.xml :
<bean id="newsListInterceptor" class="mypackage.NewsListInterceptor"/>
As the interceptor is executed for each request I also use ehcache to store the result and avoid during a select in database for each call.
Hello i am developing a web app...i am using MVC architecture in my design.
i have one form add_Flat.jsp in which admin enter the flat details and it will be stored in database (MS-Access) no other jsp page would be open on submit button.just a message displayed on add_Flat.jsp.
How can i achieve this by using MVC pattern ? do i have to write different servlet for every jsp page ? and model class for database connectivity ?
How can i achieve this by using MVC pattern ?
Let the form submit to a servlet which sets the message in the request scope and forwards back to the JSP.
do i have to write different servlet for every jsp page ?
Not necessarily. You can write a single servlet which acts as a front controller, or just use an existing MVC framework like JSF, Spring MVC, etc.
and model class for database connectivity ?
A model class should not be aware about any DB connectivity. A model class should be a simple Javabean class.
See also:
Our servlets wiki page - Contains Hello World examples and links to in-depth answers on servlet related questions here.