FacesContext#getCurrentInstance()在Filter#doFilter()中返回null [英] FacesContext#getCurrentInstance() returns null in Filter#doFilter()

问题描述

在

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

我想使用此会话

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

但是我意识到FacesContext.getCurrentInstance()返回null.我知道我可以改为使用((HttpServletRequest) req).getSession(false)进行会话，但是我的具体问题是:为什么在doFilter()方法中的人脸上下文null是什么?

But I realised that FacesContext.getCurrentInstance() returns null. I know that I can get the session using ((HttpServletRequest) req).getSession(false) instead, but my concrete question is: why is the faces context null in the doFilter() method?

我正在使用MyFaces 1.1.

I'm using MyFaces 1.1.

推荐答案

FacesContext，因为对象直接绑定到JSF请求处理生命周期，因此只能在标准JSF中使用 (用户驱动)的请求-响应过程.实际对象本身存储在与ManagedBean相对的JSF请求处理期间运行的线程中.

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.

但是. BalusC概述了一些在处理生命周期之外使用对象的步骤

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

这篇关于FacesContext#getCurrentInstance()在Filter#doFilter()中返回null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！