how to get beans from view scope

问题

I want to ask if i place my managed bean in session scope, then it is stored in session' Like if i have a bean like this

@ManagedBean
@SessionScoped
public class SessionScopedBean implements Serializable {

    .......

} //end of class SessionScopedBean

Then it stored in the session, and during my session i can get it using

session.getAttribut("SessionScopedBean");

This will give me the SessionScopedBean Object, and when session will get destroy, i will get null. Now i want to ask if i have my bean in view Scope, then how can i get it. Like

@ManagedBean
@ViewScoped
public class ViewScopedBean implements Serializable {

    .......

} //end of class ViewScopedBean

Now if the view is persist then this bean is in the view state, and when view changes, this bean will get destroy.Now i want to ask how can i get this bean from view state, if the view persist. Like

view.getAttrubute("ViewScopedBean");  //just a code. No actual implementation.

Thanks

回答1:

They're stored in the view map as available by UIViewRoot#getViewMap():

Map<String, Object> viewMap = FacesContext.getCurrentInstance().getViewRoot().getViewMap();
ViewScopedBean viewScopedBean = (ViewScopedBean) viewMap.get("viewScopedBean");
// ...

Equivalently, you should be using the session map abstraction as well which is available by ExternalContext#getSessionMap() (you ultimately want to have zero javax.servlet import declarations throughout your JSF code):

Map<String, Object> sessionMap = FacesContext.getCurrentInstance().getExternalContext().getSessionMap();
SessionScopedBean sessionScopedBean = (SessionScopedBean) sessionMap.get("sessionScopedBean");
// ...

See also:

• Get JSF managed bean by name in any Servlet related class

---

Unrelated to the concrete problem, this may not be the best way. Look at @ManagedProperty if possible.

来源：https://stackoverflow.com/questions/9172737/how-to-get-beans-from-view-scope