防止用户在注销后看到以前访问过的安全页面

我要求最终用户在注销/注销后不能返回受限页面。但是目前最终用户可以通过浏览器返回按钮、浏览浏览器历史记录甚至在浏览器地址栏中重新输入 URL 来实现这一点。

基本上,我希望最终用户不应该能够访问任何方式后登出受限制的页面。我怎样才能做到最好?我可以用 JavaScript 禁用后退按钮吗?

71370 次浏览

You can and should not disable the browser back button or history. That's bad for user experience. There are JavaScript hacks, but they are not reliable and will also not work when the client has JS disabled.

Your concrete problem is that the requested page is been loaded from the browser cache instead of straight from the server. This is essentially harmless, but indeed confusing to the enduser, because s/he incorrectly thinks that it's really coming from the server.

You just need to instruct the browser to not cache all the restricted JSP pages (and thus not only the logout page/action itself!). This way the browser is forced to request the page from the server instead of from the cache and hence all login checks on the server will be executed. You can do this using a Filter which sets the necessary response headers in the doFilter() method:

@WebFilter
public class NoCacheFilter implements Filter {


@Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
HttpServletResponse response = (HttpServletResponse) res;


response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
response.setHeader("Pragma", "no-cache"); // HTTP 1.0.
response.setDateHeader("Expires", 0); // Proxies.


chain.doFilter(req, res);
}


// ...
}

Map this Filter on an url-pattern of interest, for example *.jsp.

@WebFilter("*.jsp")

Or if you want to put this restriction on secured pages only, then you should specify an URL pattern which covers all those secured pages. For example, when they are all in the folder /app, then you need to specify the URL pattern of /app/*.

@WebFilter("/app/*")

Even more, you can do this job in the same Filter as where you're checking the presence of the logged-in user.

Don't forget to clear browser cache before testing! ;)

See also:

You can try telling the browser not to cache the homepage (using the appropriate headers - Expires, Cache-Control, Pragma). But it is not guaranteed to work. What you can do, is make an ajax call to the server on page load to check if the user is logged, and if not - redirect.

*.jsp in Url Pattern won't work if you forward a page. Try to include your servlet too.. that will make your application secure from this back button problem.

The simplest way to do it without disabling the browser back buton is by adding this code to the page_load event for the page that you don't want the user to go back to after logging out:

if (!IsPostBack)
{
if (Session["userId"] == null)
{
Response.Redirect("Login.aspx");
}
else
{
Response.ClearHeaders();
Response.ClearContent();
Response.Clear();
Session.Abandon();
Session.Remove("\\w+");
Response.AddHeader("Cache-Control", "no-cache, no-store, max-age = 0, must-revalidate");
Response.AddHeader("Pragma", "no-cache");
Response.AddHeader("Expires", "0");
}
}

The correct way to do this is to add the

Vary: Cookie

header on secured pages. When the user logs out, clear their session cookie. Then, when they navigate back after logging out, the browser cache will miss. This also has the benefit of not completely defeating caching.

An alternative to implementing a Filter is to set a 'no-cache' filter on all the secured JSPs, or on all paths. This may be a good idea if the application is small, and if you would like to customize this property for a specific pages only. We can add the following Java snippet on every secured JSP that should not be cached:

<%
response.addHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
response.setDateHeader("Expires", 0);
%>

If not on JSP, this could also be used in Controllers where routing is defined and set the headers for the 'HttpServletResponse' object.

For me the problem was , I didn't want to set headers on all pages , so I just set this header on page when logout is clicked and it clears everything related to the site :)

// Removes all site data
response.setHeader ("Clear-Site-Data", "\"cache\"");

Please read more about it over here : https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Clear-Site-Data