Struts2 validation.xml 经典验证

<validators>  
<field name="user.strUsername">  
   <!-- 验证字符串不能为空 -->  
   <field-validator type="requiredstring">  
    <!-- 去空格 -->  
    <param name="trim">true</param>  
    <!-- 错误提示信息 -->  
    <message>用户名不能为空</message>  
   </field-validator>  
    
   <!-- 验证字符串长度 -->  
   <field-validator type="stringlength">  
    <param name="minLength">2</param>  
    <param name="maxLength">20</param>  
    <message>用户名长度应在2到18个字符间</message>  
   </field-validator>  
</field>  
 
<field name="user.strPassword">  
   <field-validator type="requiredstring">  
    <param name="trim">true</param>  
    <message>密码不能为空</message>  
   </field-validator>  
    
   <field-validator type="stringlength">  
    <param name="minLength">6</param>  
    <param name="maxLength">18</param>  
    <message>密码长度应在6到18个字符之间</message>  
   </field-validator>  
</field>