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JSF 2 PreRenderViewEvent example

In JSF 2.0, you can attach a javax.faces.event.PreRenderViewEvent system event to perform custom task before a view root (JSF page) is display.

Let see a complete PreRenderViewEvent example below :

1. Managed Bean

Create a normal bean, contains a method signature “public void method-name(ComponentSystemEvent event)“, later you will ask listener to call this method.

In this method, it validate “role” in the current session, if the role is NOT equal to “admin“, then navigate it to outcome “access-denied“.


package com.mkyong;
 
import javax.faces.application.ConfigurableNavigationHandler;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.context.FacesContext;
import javax.faces.event.ComponentSystemEvent;
 
@ManagedBean(name="user")
@SessionScoped
public class UserBean{
 
  public void isAdmin(ComponentSystemEvent event){
				
	FacesContext fc = FacesContext.getCurrentInstance();
		
	if (!"admin".equals(fc.getExternalContext().getSessionMap().get("role"))){

		ConfigurableNavigationHandler nav 
		   = (ConfigurableNavigationHandler) 
			fc.getApplication().getNavigationHandler();
		
		nav.performNavigation("access-denied");
	}		
  }	
}

2. JSF Page

Now, you use f:event tag to attach “preRenderView” system event to “default.xhtml” page.

default.xhtml


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      >
     
 	<f:event listener="#{user.isAdmin}" type="preRenderView" />
 		 		
	<h:body>
	 
	    <h1>JSF 2 protected page example</h1>
	
	</h:body>

</html>

access-denied.xhtml


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
      xmlns:h="http://java.sun.com/jsf/html"
      >
 
    <h:body>
 
    	<h1>Access Denied!</h1>
 
    </h:body>
 
</html>

3. Demo

Access this page “default.xhtml“, since there is no “role” value in session object, so JSF will navigate to another page “access-denied.xhtml“.

jsf2-PreRenderViewEvent-example

Download Source Code

Download It – JSF-2-PreRenderViewEvent-Example.zip (10KB)

Reference

  1. JSF 2 PreRenderViewEvent JavaDoc

About Author

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Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter. If you like my tutorials, consider make a donation to these charities.

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Samuel Pedraza
5 years ago

EXCELENTE !! justo lo que buscaba

John Pickler
9 years ago

Is the best phase to validate this the preRenderView?

NaveenReddy Bommu
10 years ago

Thank you very much. This is cool. Nice tutorial.

MarkB
11 years ago

Just wondering, does this work with @Autowired?

If I have a Bean

@Autowired
UserService userService;

will my Service bean be init, or will it still be null (as it is when using @PostConstruct)

MB

Mark
11 years ago
Reply to  MarkB

Yes it does!

This is exactly what I have been looking for.

PS: Another good trick
wrap your preRenderView method with this
if (!FacesContext.getCurrentInstance().isPostback()) {

}

and the code wont be ran if you are posting back from a h:commandButton or something.

Raffaele
11 years ago

Hi,
there is a way for verify permission of user that is logged in application? I want to do this on every single action/actionListener calls.
For example, I want check permissions of an user that throw an event (submit or f:ajax event) client side and, before call the corresponding Action/Action Listener server side, verify if user have previleges for call it. I don’t want a global way to do this.

khocef
11 years ago

it wasn’t working for me but i add and it worked

<f:metadata>
	<f:event listener="#{navigationBean.isConnected}" type="preRenderView" />
</f:metadata>
Fayyaz Ali
11 years ago

Hello,

when using preRenderView with redirect, the page returns jsf code not html;

below is my code;


<f:event type="preRenderView" listener="#{usersController.checkAuthentication()}" />

public void checkAuthentication(){
        if(!getisloggedin()){        
            try {
                    FacesContext.getCurrentInstance().getExternalContext().redirect("Login.xhtml");
} catch (Exception e) {
                    JsfUtil.addSuccessMessage("Error occured while redirecting.");
                }
        }
}

the above code will return the actual jsf code of Login.xhtml in browser.

mrphi
9 years ago
Reply to  Fayyaz Ali

What is getisloggedin() in the code ?

kayo
12 years ago

Not working when accessing directly from
URL: http://localhost:8080/JavaServerFaces/default.xhtml

JSF: MyFaces 2.1.1

jaff
11 years ago
Reply to  kayo

you should not access the xhtml pages directly you access like this then there wont be a problem “default.jsf”