我如何从 servlet 获取用户名到 jsp 页面以将其插入到数据库中我尝试使用 session.getAttribute 它不起作用这是我的代码

登录 Servlet-Login.java

protected void doPost(HttpServletRequest request, HttpServletResponse                            response)
        throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
    String username = request.getParameter("username");
    String pass = request.getParameter("pass");
    HttpSession session = request.getSession();

    if(Validate.checkUser(username, pass))
    {
        RequestDispatcher rs = request.getRequestDispatcher("Welcome");
        rs.forward(request, response);

        session.setAttribute("username", username);
        response.sendRedirect("http://localhost:8080/login2/dietsection.html");
    }

JSP页面-dietjsp.jsp

 <%  
 String username=request.getParameter("username"); 
 session.getAttribute(username);


 Class.forName("com.mysql.jdbc.Driver"); 
 java.sql.Connection con =                            DriverManager.getConnection("jdbc:mysql://localhost:3306/logindb",
"root",""); 
PreparedStatement ps=con.prepareStatement
              ("insert into diet values(?)");
    ps.setString(1, username);

    int i=ps.executeUpdate();

   %>