會話無效后，它仍然存在，為什么？

Question

考慮一下servlet：

package controller;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class LogoutServlet
 */
@WebServlet("/loggingOut")
public class LogoutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException 
    {
        // Get the session
        HttpSession session = request.getSession(false);

        if(session != null){
            System.out.println("Here ...");
            session.invalidate();
            // forwards to the page logout.jsp
            request.getRequestDispatcher("/WEB-INF/results/logoutResult.jsp").forward(request, response);
            // response.sendRedirect("./WEB-INF/results/logoutResult.jsp");

        }

        else
        {
            System.out.println("There ...");
            // response.sendRedirect("error404.jsp");
            request.getRequestDispatcher("./WEB-INF/results/error404.jsp").forward(request, response);
        }


    }

}

在使會話無效並移至logoutResult.jsp ，如果再次到達上述servlet，則該會話仍處於“活動狀態”，並且沒有到達error404.jsp的代碼，即：

else
{
    System.out.println("There ...");
    // response.sendRedirect("error404.jsp");
    request.getRequestDispatcher("./WEB-INF/results/error404.jsp").forward(request, response);
}

我該如何解決？

非常感激

Answer 1

因為每次您訪問JSP都會創建一個新會話。 要禁用此屬性，請輸入以下指令：

<%@ page session="false" %>

Answer 2

基本上， if(session != null){在這里毫無意義。 您應該從會話中讀取屬性，並檢查其是否為空：

   String username = (String)session.getAttribute("username");
   if(username!=null)
   {
      //user is logged in
   }
   else
   {
     //user is not logged in
   }