handler

package br.com.service;



import java.io.IOException;
import java.util.Iterator;

import javax.faces.FacesException;
import javax.faces.application.FacesMessage;
import javax.faces.context.ExceptionHandler;
import javax.faces.context.ExceptionHandlerWrapper;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.faces.event.ExceptionQueuedEvent;
import javax.faces.event.ExceptionQueuedEventContext;

import br.com.util.FacesUtil;

public class ControleExceptionHandler extends ExceptionHandlerWrapper{


    private ExceptionHandler wrapped;


    public ControleExceptionHandler(ExceptionHandler wrapped) {
        this.wrapped = wrapped;
    }

    @Override
    public ExceptionHandler getWrapped() {
        return this.wrapped;
    }


    @Override
    public void handle() throws FacesException{

        Iterator<ExceptionQueuedEvent> events = getUnhandledExceptionQueuedEvents().iterator();

        while(events.hasNext()){

            ExceptionQueuedEvent event = events.next();
            ExceptionQueuedEventContext context = (ExceptionQueuedEventContext) event.getSource();

            Throwable exception = context.getException();

            UsuarioException usuarioException = getUsuarioException(exception);

            boolean handled = false;

            try {
                if (usuarioException != null){
                    handled = true;
                    FacesUtil.adicionarMensagem(FacesMessage.SEVERITY_ERROR,      usuarioException.getMessage());
                } else {
                    handled = true;
                    redirect("/index.xhtml");
                }


            } finally {
                if(handled){
                    events.remove();
                }
            }

        }

        getWrapped().handle();
    }


    private void redirect(String page){

        try{
            FacesContext fc = FacesContext.getCurrentInstance();
            ExternalContext ec = fc.getExternalContext();
            String contextPage = ec.getRequestContextPath();

            ec.redirect(contextPage + page);
            fc.responseComplete();
        } catch (IOException ioe){
            throw new FacesException(ioe);
        }

    }

    //metodo recursivo para interar em cada exceção da lista se existe uma exceção do tipo procurado
    private UsuarioException getUsuarioException(Throwable exception){

        if (exception instanceof UsuarioException){
            return (UsuarioException) exception;
        } else if (exception.getCause() !=null){
            return getUsuarioException(exception.getCause());
        }

        return null;
    }


}