Here is something you may or may not know. JSF Mojarra comes with a small extension tag library with three tags: regular expression validator, credit card validator, and focus setting tag. They are available since JSF version 1.2_09, but maybe even earlier (I didn’t check).

Page setup
Before using any of the tags, add this xml namespace to your Facelet page:

xmlns:mj="http://mojarra.dev.java.net/mojarra_ext"

Regular expression validator
mj:regexpValidator is probably all you need to validate any kind of input by setting the right expression. For example, to validate an email address:

<h:panelGrid columns="3">
   <h:outputText value="Email:" />
   <h:inputText id="email" value="#{bean.email}"
          validatorMessage="Invalid email">
       <a4j:support event="onblur" />
       <mj:regexValidator pattern=".+@.+\.[a-z]+" />
   </h:inputText>
   <rich:message for="email" />
</h:panelGrid>

Adding RichFaces into the mix to invoke validation onblur event.

Credit card validator
mj:creditcardValidator uses Luhn Algorithm to validate the input.

<h:panelGrid columns="2">
<h:outputText value="Credit card:" />
   <h:inputText id="cc" value="#{bean.creditCard}">
	<a4j:support event="onblur" />
	<mj:creditcardValidator />
   </h:inputText>
<rich:message for="cc" />
</h:panelGrid>

Focus
Lastly, mj:focus tags lets you set a focus on any component inside the current form:

<h:form id="form">
   ...
   <h:inputText id="address" value="#{bean.address}"/>
   ...
<mj:focus for="form:address"/>
</h:form>

The only thing to remember is to set for attribute to client id, not the component id.

That’s it, enjoy these “secret” tags.