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javaspring-mvchttpsession

HttpSession as a parameter in the controller

I am trying to understand how to sending HttpSession as a parameter in the spring controller works. I have a jsp which does a post request on clicking the submit button. In the controller, reading the sessions as follows

In the controller:

public ModelAndView viewEditFundClass(HttpServletRequest request,HttpServletResponse response,Model model){
HttpSession session = (HttpSession)request.getSession();

java.util.Date startDate = sesseion.getAttribute("startDate");

However, when I just change the controller to the following, I am still able to access the session

 public ModelAndView viewEditFundClass(HttpServletRequest request,HttpServletResponse response, HttpSession session,Model model)

I would like to know how this is done in Spring, ie how did the post request pass the HttpSession as a parameter? will this session be valid?

Solution

  • Assuming you're using Spring 3+ @Controller and @RequestMapping handler methods, Spring defines a default set of supported argument types for your handlers

    • Session object (Servlet API): of type HttpSession. An argument of this type enforces the presence of a corresponding session. As a consequence, such an argument is never null.

    Spring uses the strategy pattern to accomplish this, using the interface HandlerMethodArgumentResolver. It checks the parameter types of your handler methods and, for each type, tries to find a HandlerMethodArgumentResolver that will be able to resolve an argument for it.

    For HttpSession, that implementation is ServletRequestMethodArgumentResolver.