Access a managed bean from event listener – JSF

Problem

How can a JSF event listener class access another managed bean? See scenario below :

JSF page…


<h:selectOneMenu value="#{country.localeCode}" onchange="submit()">
	<f:valueChangeListener type="com.mkyong.CountryValueListener" />
   	<f:selectItems value="#{country.countryInMap}" />
</h:selectOneMenu>

country managed bean…


package com.mkyong;

import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
 
@ManagedBean(name="country")
@SessionScoped
public class CountryBean implements Serializable{

        private String localeCode;

	public void setLocaleCode(String localeCode) {
		this.localeCode = localeCode;
	}
	//...
}

ValueChangeListener…


package com.mkyong;

import javax.faces.event.AbortProcessingException;
import javax.faces.event.ValueChangeEvent;
import javax.faces.event.ValueChangeListener;
 
public class CountryValueListener implements ValueChangeListener{

	@Override
	public void processValueChange(ValueChangeEvent event)
			throws AbortProcessingException {
		
		//how to access the existing country managed bean?
		//country.setLocaleCode(event.getNewValue().toString());
		
	}
	
}

Solution

Actually, there are many ways to access an existing managed bean from an event listener class or another managed bean. See examples :

1. getApplicationMap()

If country managed bean is declared in application scope.


	CountryBean country = (CountryBean) FacesContext.getCurrentInstance().
		getExternalContext().getApplicationMap().get("country");

2. getRequestMap()

If country managed bean is declared in request scope.


	CountryBean country = (CountryBean) FacesContext.getCurrentInstance().
		getExternalContext().getRequestMap().get("country");

3. getSessionMap()

If country managed bean is declared in session scope.


	CountryBean country = (CountryBean) FacesContext.getCurrentInstance().
		getExternalContext().getSessionMap().get("country");

4. ELResolver()

Using ELResolver.


	FacesContext context = FacesContext.getCurrentInstance();
	  CountryBean country = (CountryBean) context.
	    getELContext().getELResolver().getValue(context.getELContext(), null,"country");

5. ValueExpression()

Using ValueExpression.


	FacesContext context = FacesContext.getCurrentInstance();
	  CountryBean country = (CountryBean) context.getApplication().getExpressionFactory()
            .createValueExpression(context.getELContext(), "#{country}", CountryBean.class)
              .getValue(context.getELContext());

6. evaluateExpressionGet()

Using evaluateExpressionGet.


	FacesContext context = FacesContext.getCurrentInstance();
	  CountryBean country = (CountryBean)context.getApplication()
            .evaluateExpressionGet(context, "#{country}", CountryBean.class);

Reference

6 comments on “Access a managed bean from event listener – JSF”

Chinna
September 3, 2020 at 2:32 pm

very good post thanks but little description about these different ways will give more clarity.

Mohamed Uvais
September 12, 2017 at 7:07 pm

How to get the view scoped and flash scoped bean from event listener ?

foldvari91
March 11, 2015 at 11:00 pm

It helped me a lot in 2015, thanks! 🙂

Diogo Alves
January 27, 2015 at 3:09 am

Thank you.

Saravanan KM
December 23, 2013 at 5:39 pm

Very useful and clear information . Thank you

Skyhan
May 15, 2012 at 10:48 pm
Great article on JSF managed beans, thanks. I have a question, though: I need to access an application-scoped managed bean to modify certain properties from within an HttpSessionListener.

I already used something like the following:
```
@Override
public void sessionDestroyed(HttpSessionEvent se) {
    HttpSession session = se.getSession();
    User user = userService.findBySessionId(session.getId());    

    ExternalContext externalContext = FacesContext.getCurrentInstance().getExternalContext();

     ApplicationScopedBean appBean = (ApplicationScopedBean) externalContext.getApplicationMap().get("appBean");
     appBean.getConnectedUsers().remove(user);
}
```
externalContext = FacesContext.getCurrentInstance().getExternalContext() causes a null pointer exception already, and even if it didn’t I’m not sure appBean could be accessible the above way.

Any ideas?