How to logout session using invalidate() in servlet

Question

protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        HttpSession session = request.getSession();
        if(session != null)
        {
            try
            {
                response.setHeader("Cache-Control","no-cache"); //Forces caches to obtain a new copy of the page from the origin server
                response.setHeader("Cache-Control","no-store"); //Directs caches not to store the page under any circumstance
                response.setDateHeader("Expires", 0); //Causes the proxy cache to see the page as "stale"
                response.setHeader("Pragma","no-cache"); //HTTP 1.0 backward compatibility
                session.setAttribute("admin_name",null);
                session.invalidate();
                response.sendRedirect("login.jsp");
            }
            catch(Exception e)
            {
                System.out.println(e.getMessage());
                System.out.println(e);
            }

        }
        else
        {


        }
    }

This is my servlet. I am going to logout the session that i created using name admin_name. when i logout the session it successfully hit the login page. but when i press back button it go to the previous page. I didn't understood why these happen even if i invalidate that session. but when i refresh that page it will again hit the login page.

Here the code that i used in jsp page.

<%
        String name = null;
        if (session.getAttribute("admin_name") == null) {
            response.sendRedirect("login.jsp");
        } else {
            name = (String) session.getAttribute("admin_name");
        }
    %>

Answer 1

Session is invalidated immediately once you call .invalidate method

From docs ,

invalidate

void invalidate()
Invalidates this session then unbinds any objects bound to it.

From your question

I didn't understood why these happen even if i invalidate that session. 

but when i refresh that page it will again hit the login page.

It is because the page is loaded from the browser cache , even if it goes to the previous page you can't send any request from the page loaded

Update

Check this How to clear browser cache using java

Hope this helps!!