Question

8. Read the following java code, finish the subtasks about sessions. (15 Points) 1 HttpSession session = request.getSession(); if(session.isNew()) { 2 3 visits++; } (1) Explain what the sessions are, and the intention of using sessions. (5 Points) (2) What does the HttpSession object store? (3 Points) (3) When an HTTP request is received but it does not contain a session ID, what will the HttpSession object do? (3 Points) (4) How can Session ID created by the web server return to the web browser? (2 Points) (5) What's the function of the statement session.isNew()? (2 Points)

Answer 1

(1) Sessions are a way to store and track information about a user's interaction with a web application over multiple requests. The intention of using sessions is to maintain stateful communication between the web server and the web browser. It allows the server to remember user-specific data, such as login credentials or user preferences, throughout the user's session on the website. Sessions enable personalized and customized experiences for each user and facilitate the storage of temporary data during a user's visit.

(2) The HttpSession object stores user-specific data as key-value pairs. It provides methods to store, retrieve, and manipulate this data during a user's session. The data stored in the HttpSession object can include user login information, user preferences, shopping cart contents, and any other application-specific data that needs to be associated with a specific user.

(3) When an HTTP request is received but it does not contain a session ID, the HttpSession object creates a new session for the user. It generates a unique session ID and associates it with the user's session data. The session ID is typically stored in a cookie on the user's browser, which is then sent back to the server with subsequent requests to identify and associate the requests with the correct session data.

(4) The Session ID created by the web server can be returned to the web browser in multiple ways. One common approach is by setting a cookie on the browser with the session ID as its value. This cookie is then automatically included in subsequent requests sent by the browser to the server, allowing the server to identify and associate the requests with the correct session data.

(5) The function of the statement `session.isNew()` is to determine whether the HttpSession object represents a new session or an existing session. It returns `true` if the session is new and has just been created, or `false` if the session already existed before the current request. In the given code snippet, if `session.isNew()` returns `true`, it means that the session was just created, and the `visits` counter is incremented to track the number of visits by the user.