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Unit- 4: Session Management
Q14. You have a use case in your web application that adds several session-scoped attributes. At the end of the use case, one of these objects, the manager attribute, is removed and then it needs to decide which of the other session-scoped attributes to remove. How can this goal be accomplished?
A. The object of the manager attribute should implement the HttpSessionBindingListener and it should call the removeAttribute method on the appropriate session attributes.
B. The object of the manager attribute should implement the HttpSessionListener and it should call the removeAttribute method on the appropriate session attributes.
C. The object of the manager attribute should implement the HttpSessionBindingListener and it should call the deleteAttribute method on the appropriate session attributes.
D. The object of the manager attribute should implement the HttpSessionListener and it should call the deleteAttribute method on the appropriate session attributes.
Answer: A
Q15. Your web site has many user-customizable features, for example font and color preferences on web pages. Your IT department has already built a subsystem for user preferences using Java SE's lang.util.prefs package APIs and you have been ordered to reuse this subsystem in your web application. You need to create an event listener that stores the user's Preference object when an HTTP session is created. Also, note that user identification information is stored in an HTTP cookie.
Which partial listener class can accomplish this goal?
A. public class UserPrefLoader implements HttpSessionListener {
public void sessionCreated(HttpSessionEvent se) {
MyPrefsFactory myFactory = (MyPrefsFactory) se.getServletContext().getAttribute("myPrefsFactory");
User user = getUserFromCookie(se);
myFactory.setThreadLocalUser(user);
Preferences userPrefs = myFactory.userRoot();
se.getSession().setAttribute("prefs", userPrefs);
}
// more code here
}
B. public class UserPrefLoader implements SessionListener {
public void sessionCreated(SessionEvent se) {
MyPrefsFactory myFactory = (MyPrefsFactory) se.getContext().getAttribute("myPrefsFactory");
User user = getUserFromCookie(se);
myFactory.setThreadLocalUser(user);
Preferences userPrefs = myFactory.userRoot();
se.getSession().addAttribute("prefs", userPrefs);
}
// more code here
}
C. public class UserPrefLoader implements HttpSessionListener {
public void sessionInitialized(HttpSessionEvent se) {
MyPrefsFactory myFactory = (MyPrefsFactory) se.getServletContext().getAttribute("myPrefsFactory");
User user = getUserFromCookie(se);
myFactory.setThreadLocalUser(user);
Preferences userPrefs = myFactory.userRoot();
se.getHttpSession().setAttribute("prefs", userPrefs);
}
// more code here
}
D. public class UserPrefLoader implements SessionListener {
public void sessionInitialized(SessionEvent se) {
MyPrefsFactory myFactory = (MyPrefsFactory) se.getServletContext().getAttribute("myPrefsFactory");
User user = getUserFromCookie(se);
myFactory.setThreadLocalUser(user);
Preferences userPrefs = myFactory.userRoot();
se.getSession().addAttribute("prefs", userPrefs);
}
// more code here
}
Answer: A
Q16. For which three events can web application event listeners be registered?(Choose three.)
A. when a session is created B. after a servlet is destroyed
C. when a session has timed out D. when a cookie has been created
E. when a servlet has forwarded a request F. when a session attribute value is changed
Answer: A, C, F
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