<!DOCTYPE form-validation  PUBLIC  
"-//Apache Software Foundation//DTD Commons Validator Rules Configuration 1.1.3//EN"
  "http://jakarta.apache.org/commons/dtds/validator_1_1_3.dtd">


<form-validation>
    <formset>
        <form name="formForm">
            <field property="login" depends="required">
                <arg key="label.login"/>
                <msg key="errors.required" name="required"/>
            </field>
        </form>
    </formset>
</form-validation>

<!DOCTYPE struts-config  PUBLIC 
  "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"
  "http://struts.apache.org/dtds/struts-config_1_2.dtd">

<struts-config>

    <controller processorClass="org.apache.struts.tiles.TilesRequestProcessor"/>
    <message-resources parameter="Message"/>
    <plug-in className="org.apache.struts.tiles.TilesPlugin">
        <set-property property="definitions-config" value="/WEB-INF/tiles-defs.xml"/>
    </plug-in>
    <plug-in className="org.apache.struts.validator.ValidatorPlugIn">
        <set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
        <set-property property="stopOnFirstError" value="false"/>
    </plug-in>


    <form-beans>
        <form-bean name="formForm" type="FormForm"/>
    </form-beans>

    <action-mappings>

        <action path="/test"
                type="TestGoAction"
                name="formForm"
                scope="request"
                validate="false">
            <forward name="success" path="/form.jsp"/>
        </action>

        <action path="/formGoAction"
                type="FormGoAction"
                name="formForm"
                attribute="login"
                scope="request"
                validate="false"
                input="/form.jsp">
            <forward name="success" path="/reg_ok.jsp"/>
        </action>

    </action-mappings>

</struts-config>

 public   class  FormForm  extends  ValidatorForm {

     private  String  sLogin;

     public  String getLogin () {  return  sLogin; }
     public   void  setLogin (String sLogin) {  this .sLogin = sLogin; }

     public   void  reset(ActionMapping mapping, HttpServletRequest request) {
         this .sLogin =  null ;
    }

 public   class  FormGoAction
         extends  Action {

     public  ActionForward execute(ActionMapping mapping,
                                 ActionForm form,
                                 HttpServletRequest request,
                                 HttpServletResponse response
    )
             throws  Exception {

        FormForm formForm = (FormForm) form;
        request.setCharacterEncoding("windows-1251");
         return  mapping.findForward("success");
    }
}

#Error Resources
label.login=Login
## -- standard errors --
errors.header=<UL>
errors.prefix=<LI>
errors.suffix=</LI>
errors.footer=</UL>
# -- validator --
errors.invalid={ 0 } is invalid.
errors.maxlength={ 0 } can not be greater than { 1 } characters.
errors.minlength={ 0 } can not be less than { 1 } characters.
errors.range={ 0 } is not in the range { 1 } through { 2 }.
errors.required={ 0 } is required.
errors. byte ={ 0 } must be an  byte .
errors.date={ 0 } is not a date.
errors. double ={ 0 } must be an  double .
errors. float ={ 0 } must be an  float .

        <action path="/formGoAction"
                type="FormGoAction"
                name="formForm"
                attribute="login"
                scope="request"
                validate="false"
                input="/form.jsp">
            <forward name="success" path="/reg_ok.jsp"/>
        </action>

<set-property property="pathnames" value="/WEB-INF/validator-rules.xml

<set-property property="pathnames"
                      value="/org/apache/struts/validator/validator-rules.xml

validate=true 

Error:Error: null 

надеюсь я вам дохочиво объяснил :)

       
 <validator name="twofields"
         classname="com.strutsValidators.Validators"
         method="validateTwoFields"
         methodParams="java.lang.Object,
         org.apache.commons.validator.ValidatorAction,
         org.apache.commons.validator.Field,
         org.apache.struts.action.ActionMessages,
         org.apache.commons.validator.Validator,
         javax.servlet.http.HttpServletRequest"
         depends=""
         msg="errors.twofields">

<field property="password" depends="required,twofields">
                <arg key="RegPhyForm.password"/>
                <arg position="0" key="RegPhyForm.password"/>
                <arg position="1" key="RegPhyForm.passwordAgain"/>
                <msg key="errors.required" name="required"/>
                <msg key="errors.twofields" name="twofields"/>
                <var>
                    <var-name>secondProperty</var-name>
                    <var-value>passwordAgain</var-value>
                </var>
            </field>

            <field property="passwordAgain" depends="required">
                <arg key="RegPhyForm.passwordAgain"/>
                <msg key="errors.required" name="required"/>
            </field>

 public   class  Validators {
     public   static   boolean  validateTwoFields(
        Object bean,
        ValidatorAction va,
        Field field,
        ActionErrors errors,
        HttpServletRequest request,
        ServletContext application,
    Validator val) {
        String value = ValidatorUtils.getValueAsString(
            bean,
            field.getProperty());
        String sProperty2 = field.getVarValue("secondProperty");
        String value2 = ValidatorUtils.getValueAsString(
            bean,
            sProperty2);
         if  (!GenericValidator.isBlankOrNull(value)) {
            try  {
               if  (!value.equals(value2)) {
                 errors.add(field.getKey(),
                    Resources.getActionMessage(
                        val,
                        request,
                        va,
                        field));

                  return  false;
              }
           }  catch  (Exception e) {
                 errors.add(field.getKey(),
                    Resources.getActionMessage(
                        val,
                        request,
                        va,
                        field));
                  return  false;
           }
        }

         return  true;
    }