CDI Interceptor not simultaneous to current request in servlet - servlets

Question

Sorry for the title, i have no idea to get better title.
I create a simple servlet and implements CDI interceptor.
This is my servlet
#Inject
UserManagement user;
protected void doGet(HttpServletRequest request, HttpServletResponse response) {
user.setUsername(request.getParameter("username"));
response.getWriter().println(user.getMessage());
}
This is UserManagement bean:
#SessionScoped
public class UserManagement implements Serializable{
private String username;
private String message = "";
#UsernameSet
public void setUsername(String username){
this.username = username;
}
}
This is interceptor binding (#UsernameSet):
#InterceptorBinding
#Inherited
#Target({ TYPE, METHOD })
#Retention(RUNTIME)
#Documented
public #interface UsernameSet {
}
This is the interceptor:
#UsernameSet
#Interceptor
public class UserInterceptor implements Serializable {
#Inject
UserManagement user;
#AroundInvoke
public Object aroundInvoke(InvocationContext ic) throws Exception {
LOGGER.info("Entering method: " + ic.getMethod().getName());
user.setMessage("Hello " + user.getUsername());
return ic.proceed();
}
}
The interceptor does work but the servlet return UserManagement bean from previous request, although the logger shows immediately.
example
First Request:
localhost?username=smitty
Browser screen:
Hello
Second Request:
localhost?username=werben
Browser screen:
Hello smitty
Third Request:
localhost?username=jensen
Browser screen:
Hello werben

Answer 1

When you create an interceptor, it's invoked either before or after your method is called. With the way you have written yours, it is invoked before your method is called. InvocationContext.proceed will effectively call your method (and other interceptors if others are wired in).
To get the behavior you're looking for, you can switch to this:
#UsernameSet
#Interceptor
public class UserInterceptor implements Serializable {
#Inject
UserManagement user;
#AroundInvoke
public Object aroundInvoke(InvocationContext ic) throws Exception {
LOGGER.info("Entering method: " + ic.getMethod().getName());
Object result = ic.proceed();
user.setMessage("Hello " + user.getUsername());
return result;
}
}