jsf - FacesContext#getCurrentInstance() 在 Filter#doFilter() 中返回 null

Question

里面一个

public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)

我想使用

FacesContext.getCurrentInstance().getExternalContext().getSession(false);

但我意识到，FacesContext.getCurrentInstance()回报null。我知道我可以((HttpServletRequest) req).getSession(false)改为使用会话，但我的具体问题是：为什么null方法中的面孔上下文doFilter()？

我正在使用 MyFaces 1.1。

Answer 1

FacesContext as an object is tied directly to the JSF request processing lifecycle and as a result is only available during a standard JSF (user-driven) request-response process. The actual object itself is stored in a thread that runs during the processing of a JSF request, vis-a-vis a ManagedBean.

But. BalusC has outlined some steps to get your hands on the object outside of the processing lifecycle here. :)