Validator框架可以很方便的实现对表单的验证，配合struts1框架的插件技术进行实现。

首先Validator框架有validation.xml和validation-rules.xml两个配置文件，我们需要配置validation.xml文件，并将这两个文件部署到Web应用的/WEB-INF文件夹下（建议），这里没有说到配置validator-rules.xml。因为这个配置文件中包含了一些默认的验证规则，我们先使用一些简单的规则。具体的validator-rules.xml配置文件模板如下：

<!--
<?xml version="1.0" encoding="UTF-8"?>

<!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">
  $Id: validator-rules.xml 159291 2005-03-28 20:19:29Z niallp $

   This file contains the default Struts Validator pluggable validator
   definitions.  It should be placed somewhere under /WEB-INF and
   referenced in the struts-config.xml under the plug-in element
   for the ValidatorPlugIn.

      <plug-in className="org.apache.struts.validator.ValidatorPlugIn">
        <set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
      </plug-in>

   These are the default error messages associated with
   each validator defined in this file.  They should be
   added to your projects ApplicationResources.properties
   file or you can associate new ones by modifying the
   pluggable validators msg attributes in this file.

   # Struts Validator Error Messages
   errors.required={0} is required.
   errors.minlength={0} can not be less than {1} characters.
   errors.maxlength={0} can not be greater than {1} characters.
   errors.invalid={0} is invalid.

   errors.byte={0} must be a byte.
   errors.short={0} must be a short.
   errors.integer={0} must be an integer.
   errors.long={0} must be a long.
   errors.float={0} must be a float.
   errors.double={0} must be a double.

   errors.date={0} is not a date.
   errors.range={0} is not in the range {1} through {2}.
   errors.creditcard={0} is an invalid credit card number.
   errors.email={0} is an invalid e-mail address.

   Note: Starting in Struts 1.2.0 the default javascript definitions have
         been consolidated to commons-validator. The default can be overridden
         by supplying a <javascript> element with a CDATA section,just as
         in struts 1.1.

-->
<form-validation>
    <global>
        <validator name="required" classname="org.apache.struts.validator.FieldChecks" method="validaterequired" 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" msg="errors.required"/>
        <validator name="requiredif" classname="org.apache.struts.validator.FieldChecks" method="validaterequiredIf" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" msg="errors.required"/>
        <validator name="validwhen" msg="errors.required" classname="org.apache.struts.validator.validwhen.ValidWhen" method="validateValidWhen" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest"/>
        <validator name="minlength" classname="org.apache.struts.validator.FieldChecks" method="validateMinLength" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.minlength" jsFunction="org.apache.commons.validator.javascript.validateMinLength"/>
        <validator name="maxlength" classname="org.apache.struts.validator.FieldChecks" method="validateMaxLength" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.maxlength" jsFunction="org.apache.commons.validator.javascript.validateMaxLength"/>
        <validator name="mask" classname="org.apache.struts.validator.FieldChecks" method="validateMask" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.invalid"/>
        <validator name="byte" classname="org.apache.struts.validator.FieldChecks" method="validateByte" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.byte" jsFunctionName="ByteValidations"/>
        <validator name="short" classname="org.apache.struts.validator.FieldChecks" method="validateShort" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.short" jsFunctionName="ShortValidations"/>
        <validator name="integer" classname="org.apache.struts.validator.FieldChecks" method="validateInteger" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.integer" jsFunctionName="IntegerValidations"/>
        <validator name="long" classname="org.apache.struts.validator.FieldChecks" method="validateLong" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.long"/>
        <validator name="float" classname="org.apache.struts.validator.FieldChecks" method="validateFloat" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.float" jsFunctionName="FloatValidations"/>
        <validator name="double" classname="org.apache.struts.validator.FieldChecks" method="validateDouble" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.double"/>
        <validator name="date" classname="org.apache.struts.validator.FieldChecks" method="validateDate" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.date" jsFunctionName="DateValidations"/>
        <validator name="intRange" classname="org.apache.struts.validator.FieldChecks" method="validateIntRange" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="integer" msg="errors.range"/>
        <validator name="floatRange" classname="org.apache.struts.validator.FieldChecks" method="validateFloatRange" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="float" msg="errors.range"/>
        <validator name="doubleRange" classname="org.apache.struts.validator.FieldChecks" method="validateDoubleRange" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="double" msg="errors.range"/>
        <validator name="creditCard" classname="org.apache.struts.validator.FieldChecks" method="validateCreditCard" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.creditcard"/>
        <validator name="email" classname="org.apache.struts.validator.FieldChecks" method="validateEmail" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.email"/>
        <validator name="url" classname="org.apache.struts.validator.FieldChecks" method="validateUrl" methodParams="java.lang.Object,javax.servlet.http.HttpServletRequest" depends="" msg="errors.url"/>
        <!--

               This simply allows struts to include the validateUtilities into a page,it should
               not be used as a validation rule.

        -->
        <validator name="includeJavaScriptUtilities" classname="" method="" methodParams="" depends="" msg="" jsFunction="org.apache.commons.validator.javascript.validateUtilities"/>
    </global>
</form-validation>

作为一个初学者，对于这样的配置文件如果自己编写，自认为还是太过复杂，毕竟东西太多不好熟记。感谢某位仁兄上传了该配置文件！可能在下载的validator框架对应的jar包当中有该文件，但是目前我还没有找到。。。

对于validation.xml文件需要自己进行配置，可以根据网上的详解，这里只是为了方便validator-rules.xml这个文件的编写！