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I would like to share Session Attributes betweet two Controllers in Spring MVC, using the @SessionAttributes annotation.
Here is a simple code I use to test the attributes sharing : AController.java
@Controller
@SessionAttributes("myParam")
public class AController {
@RequestMapping(value="/a")
public String handle(Model model){
if(!model.containsAttribute("myParam"))
model.addAttribute("myParam", randomInt());
return "a";
}
private int randomInt(){
return new Random().nextInt(100);
}
}
a.jsp
<%@taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<h1>Page A</h1>
<p>Param = ${myParam}</p>
</html>
BController.java
@Controller
@SessionAttributes("myParam")
public class BController {
@RequestMapping(value="/b")
public String handle(Model model){
if(!model.containsAttribute("myParam"))
model.addAttribute("myParam", randomInt());
return "b";
}
private int randomInt(){
return new Random().nextInt(100);
}
}
b.jsp
<%@taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<h1>Page B</h1>
<p>Param = ${myParam}</p>
The behaviour I expect is to go to the /a URL, myParam would be set to a random value between 0 and 99, then this value would be shared between the two controllers.
However,what happens is the following: I go to the /a URL, myParam is set to a value (let's say 10). Then i go to the /b URL, myParam is set to another value (let's say 20). When I go back to the /a URL, myParam value is the one set by the BController ( myParam =20).
Once the two controllers methods have been executed, the value is shared, but before, each controller redefines a new value.
It seems like if a Controller has never set a value to a SessionAttribute, it does not detect that attribute if it was set by another Controller.
I really would like to be able to share session attributes betwen controllers without using the HttpSession object and sticking with Spring MVC 3 objects.
I would like to know if I missed something or if there are other practices to share data in a session between controllers.
NB : the webapp was deployed on a Tomcat7 server.
312
@SessionAttribute annotation retrieve the existing attribute from the session. This annotation allows you to tell Spring which of your model attributes will also be copied to HttpSession before rendering the view.
@ModelAttribute on a method argument essentially binds the model(what you have submitted through the fields) with the type (in this case Employee ) and exposes this bound type as a model that you can use in your jsp. It is not a Spring bean at all at this point, just an object scoped to the request.
In Spring MVC, @SessionAttributes are not meant to be shared accross Controllers.
What I did instead was to create an object (via a POJO) with the Session scope, that holds all the values I need to store for a Session.
I then use the JDK dynamic proxy to Autowire the object to the Controllers.
148
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