无法从Servlet过滤器内的FacesContext中检索Session

Question

在验证我的用户之后,我想在会话中将引用添加到当前登录用户.

这里我是如何在setCurrentUser方法中做到的:

FacesContext facesContext = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession) facesContext.getExternalContext().getSession(true);
session.setAttribute("CURRENT_USER", currentUser);

不幸的是,session引用始终为null!

或者,我尝试使用sessionMap

FacesContext facesContext = FacesContext.getCurrentInstance();
Map<String, Object> sessionMap = facesContext.getExternalContext().getSessionMap();
sessionMap.put("CURRENT_USER", currentUser);

这个例外情况很糟糕:

java.lang.UnsupportedOperationException
    at java.util.AbstractMap.put(AbstractMap.java:186)
    (...)

我究竟做错了什么 ？

我的控制器的完整代码

UserController.java

public class UserController implements Filter {
    private FilterConfig fc;
    private static final String CURRENT_USER = "CURRENT_USER";

    public void init(FilterConfig filterConfig) throws ServletException {
        fc = filterConfig;
        log(">> Filter initialized");
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        // Authenticate user
        // ...

        // Save refernce in Session
        setCurrentUser(currentUser);

        //(...)
    }

    public static void setCurrentUser(User u) {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        HttpSession session = (HttpSession) facesContext.getExternalContext().getSession(true);
        session.setAttribute(CURRENT_USER, u);// session is always NULL
    }

    public static User getCurrentUser() {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        HttpSession session = (HttpSession) facesContext.getExternalContext().getSession(true);       
        return (User)session.getAttribute(CURRENT_USER);
    }

    //...   
}

JSF 2.0
JBoss 5.1.0.GA

Answer 1

该FacesContext不是在现有Filter的Filter调用之前的FacesServlet.

您应该从request参数中获取会话.

HttpSession session = ((HttpServletRequest) request).getSession();
session.setAttribute("user", currentUser);
// ...

一旦你进入JSF上下文(例如在JSF托管bean或JSF视图中),那么这将在getSessionMap()相同的属性名称上可用

User user = (User) externalContext.getSessionMap().get("user");

或者只是#{user}在EL:

@ManagedProperty("#{user}")
private User user;