Мessage resource bundles should be registered in the Faces configuration (faces-config.xml) file of your application as <message-bundle> inside the <application> element. Name of a resource should be specified without language or country code and without .properties extension. Supported locales should be specified inside the <supported-locale> element.

Registering resource bundles in the Faces configuration file:

<application>

      <locale-config>

            <default-locale>en</default-locale>

            <supported-locale>en</supported-locale>

            <supported-locale>de</supported-locale>

            <supported-locale>it</supported-locale>

      </locale-config>

      <message-bundle>demo.message</message-bundle>

</application>

For the application we will use JSF javax.faces.component.UIViewRoot.setLocale method that will set a needed Locale (each link will invoke corresponding method — there are, off course, another ways to do that).

ChangeLocale Java class with three methods for setting the correponding Locale:

package demo;


 import java.util.Locale;

 import javax.faces.context.FacesContext;


 public class ChangeLocale {

    public String germanAction() {

       FacesContext context = FacesContext.getCurrentInstance();

       context.getViewRoot().setLocale(Locale.GERMAN);

       return null;

    }


    public String englishAction() {

       FacesContext context = FacesContext.getCurrentInstance();

       context.getViewRoot().setLocale(Locale.ENGLISH);

       return null;

    }

    

    public String italianAction() {

        FacesContext context = FacesContext.getCurrentInstance();

        context.getViewRoot().setLocale(Locale.ITALIAN);

        return null;

     }

}

Recently, the JSP page will look as following:

<h:form>

      <a4j:loadBundle var="msg" basename="demo.message"/>

      <h:outputText id="messageBundle" value="#{msg.greeting}"/>

      <a4j:commandLink value="De" action="#{changeLocale.germanAction}" reRender="messageBundle" />

      <a4j:commandLink value="Eng" action="#{changeLocale.englishAction}" reRender="messageBundle" />

      <a4j:commandLink value="It" action="#{changeLocale.italianAction}" reRender="messageBundle" />

</h:form> 

As an output we will get a simple application with English "Hello!" by default. Clicking on links "De", "Eng" and "It" will show the messages specified within the corresponding *.properties file. To reference to a particular bundle item during an Ajax update it is necessary to point the component(s) that shold be re-rendered (in this example it is done with the help of <a4j:commandLink> "reRender" attribute).