Get JSF managed bean by name in any Servlet related class

Question

I m trying to write a custom servlet  for AJAX JSON  in which I would like to reference my  ManagedBeans by name  I m hoping to map   http   host app myBean myProperty  to     ManagedBean name  myBean   public class MyBean       public String getMyProperty        Is it possible to load a bean by name from a regular servlet  Is there a JSF servlet or helper I could use for it   I seem to be spoilt by Spring in which all this is too obvious

User · Answer

Have you tried an approach like on this link? I'm not sure if createValueBinding() is still available but code like this should be accessible from a plain old Servlet. This does require to bean to already exist.

http://www.coderanch.com/t/211706/JSF/java/access-managed-bean-JSF-from

 FacesContext context = FacesContext.getCurrentInstance();  
 Application app = context.getApplication();
 // May be deprecated
 ValueBinding binding = app.createValueBinding("#{" + expr + "}"); 
 Object value = binding.getValue(context);

User · Answer

I use the following method   public static  lt T gt  T getBean final String beanName  final Class lt T gt  clazz        ELContext elContext   FacesContext getCurrentInstance   getELContext        return  T  FacesContext getCurrentInstance   getApplication   getELResolver   getValue elContext  null  beanName       This allows me to get the returned object in a typed manner

User · Answer

I use this   public static  lt T gt  T getBean Class lt T gt  clazz        try           String beanName   getBeanName clazz           FacesContext facesContext   FacesContext getCurrentInstance            return facesContext getApplication   evaluateExpressionGet facesContext         beanName        clazz         return facesContext getApplication   getELResolver   getValue facesContext getELContext    null  nomeBean         catch  Exception ex            return null           public static  lt T gt  String getBeanName Class lt T gt  clazz        ManagedBean managedBean   clazz getAnnotation ManagedBean class       String beanName   managedBean name         if  StringHelper isNullOrEmpty beanName             beanName   clazz getSimpleName            beanName   Character toLowerCase beanName charAt 0     beanName substring 1              return beanName      And then call   MyManageBean bean   getBean MyManageBean class     This way you can refactor your code and track usages without problems

User · Answer

You can get the managed bean by passing the name   public static Object getBean String beanName       Object bean   null      FacesContext fc   FacesContext getCurrentInstance        if fc  null            ELContext elContext   fc getELContext             bean   elContext getELResolver   getValue elContext  null  beanName              return bean

User · Answer

I had same requirement    I have used the below way to get it    I had session scoped bean     ManagedBean name  mb    SessionScopedpublic  class ManagedBean        --------     I have used the below code in my servlet doPost   method    ManagedBean mb    ManagedBean  request getSession   getAttribute  mb      it solved my problem

User · Answer

In a servlet based artifact  such as  WebServlet   WebFilter and  WebListener  you can grab a  quot plain vanilla quot  JSF  ManagedBean  RequestScoped by  Bean bean    Bean  request getAttribute  quot beanName quot     and  ManagedBean  SessionScoped by  Bean bean    Bean  request getSession   getAttribute  quot beanName quot     and  ManagedBean  ApplicationScoped by  Bean bean    Bean  getServletContext   getAttribute  quot beanName quot     Note that this prerequires that the bean is already autocreated by JSF beforehand  Else these will return null  You d then need to manually create the bean and use setAttribute  quot beanName quot   bean    If you re able to use CDI  Named instead of the since JSF 2 3 deprecated  ManagedBean  then it s even more easy  particularly because you don t anymore need to manually create the beans   Inject private Bean bean   Note that this won t work when you re using  Named  ViewScoped because the bean can only be identified by JSF view state and that s only available when the FacesServlet has been invoked  So in a filter which runs before that  accessing an  Injected  ViewScoped will always throw ContextNotActiveException   Only when you re inside  ManagedBean  then you can use  ManagedProperty   ManagedProperty  quot   bean  quot   private Bean bean   Note that this doesn t work inside a  Named or  WebServlet or any other artifact  It really works inside  ManagedBean only   If you re not inside a  ManagedBean  but the FacesContext is readily available  i e  FacesContext getCurrentInstance   doesn t return null   you can also use Application evaluateExpressionGet    FacesContext context   FacesContext getCurrentInstance    Bean bean   context getApplication   evaluateExpressionGet context   quot   beanName  quot   Bean class    which can be convenienced as follows   SuppressWarnings  quot unchecked quot   public static  lt T gt  T findBean String beanName        FacesContext context   FacesContext getCurrentInstance        return  T  context getApplication   evaluateExpressionGet context   quot    quot    beanName    quot   quot   Object class      and can be used as follows  Bean bean   findBean  quot bean quot      See also   Backing beans   ManagedBean  or CDI Beans   Named

[jsf] Get JSF managed bean by name in any Servlet related class

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