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Tutorials > Servlet > Servlet Session Management

Servlet Session Management

Servlet Session Management is the process of managing user sessions in a web application. A session is a sequence of related HTTP requests and responses that occur between a user and a web application. In a servlet-based web application, sessions are managed by the Servlet API, which provides several interfaces and classes for working with sessions.

Here's an example of how to manage a user session in a servlet-based web application:

  • Create a Servlet to Create or Retrieve Session:
java
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public class SessionServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session object for the current request
        HttpSession session = request.getSession();
 
        // Set session attributes
        session.setAttribute("username", "john.doe");
        session.setAttribute("language", "en");
 
        // Retrieve session attributes
        String username = (String) session.getAttribute("username");
        String language = (String) session.getAttribute("language");
 
        // Use session attributes in the response
        PrintWriter out = response.getWriter();
        out.println("Hello " + username + ", your preferred language is " + language);
    }
}

In this example, we use the getSession() method to retrieve the current user session. We then set and retrieve session attributes using the setAttribute() and getAttribute() methods, respectively.

  • Set Session Timeout:
java
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public class SessionTimeoutServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session object for the current request
        HttpSession session = request.getSession();
 
        // Set session timeout to 30 minutes (in seconds)
        session.setMaxInactiveInterval(1800);
 
        // Use session attributes in the response
        PrintWriter out = response.getWriter();
        out.println("Session timeout set to " + session.getMaxInactiveInterval() + " seconds");
    }
}

In this example, we use the setMaxInactiveInterval() method to set the session timeout to 30 minutes. The timeout is specified in seconds.

  • Invalidate a Session:
java
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public class SessionInvalidationServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session object for the current request
        HttpSession session = request.getSession();
 
        // Invalidate the session
        session.invalidate();
 
        // Use session attributes in the response
        PrintWriter out = response.getWriter();
        out.println("Session invalidated");
    }
}

In this example, we use the invalidate() method to invalidate the current user session. This will remove all session attributes and end the session.

  • Share Session Attributes Between Servlets:
java
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public class FirstServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session object for the current request
        HttpSession session = request.getSession();
 
        // Set a session attribute
        session.setAttribute("attribute1", "value1");
 
        // Redirect to the second servlet
        response.sendRedirect("second");
    }
}
 
public class SecondServlet extends HttpServlet {
 
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get the session object for the current request
        HttpSession session = request.getSession();
 
        // Retrieve the session attribute set by the first servlet
        String attribute1 = (String) session.getAttribute("attribute1");
 
        // Use the session attribute in the response
        PrintWriter out = response.getWriter();
        out.println("Attribute 1: " + attribute1);
    }
}

In this example, we set a session attribute in the first servlet and then redirect to the second servlet. In the second servlet, we retrieve the session attribute set by the first servlet and use it in the response.

Overall, session management is a critical aspect of building web applications, as it allows you to maintain stateful interactions with users. By using the built-in session management features of the Servlet API, you can create robust and scalable web applications that can handle user sessions efficiently.



Next: Servlet Request and Response

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