action-validation.xml in struts 2

I have started a web application using struts 2. Apache tomcat 6.0 is my web server. It is clear to me that we can validate data using action-validation.xml as my login-validation.xml is –

<validators> <field name="username"> <field-validator type="requiredstring"> <message>Login name is required</message> </field-validator> </field> </validators>

But it is only for pre-defined types like requiredstring, int, email etc. If I want that user name must have a character for example ‘*” then how can we achieve this type of validation in struts 2.

And also tell me what I have explained above is a server side validation or client side validation.

From stackoverflow

• For the username, there are a couple ways to approach it.

  You could use the fieldexpression built-in validator and give it a regular expression to match the required user name characters.

  You could just validate the incoming user name in the action and add a field error if it fails validation.

  The above are server-side validations. For something as simple as requiring special characters in a user name, client-side JavaScript validation would probably be easiest.

• For your case, i think the regex validor works for your problem:

  <validators> 
  
     <field name="username"> 
      <field-validator type="requiredstring"> 
      <message>Login name is required</message> 
      </field-validator> 
  
          <field-validator type="regex">
             <param name="expression"><![CDATA[(.*\*.*)]]></param>
         <message>Login name must contain a *</message> 
        </field-validator>
      </field>
  
  </validators>
  

  If the built-in validators can't satisfy your requirement, you can also write your customized validator.