Struts2 Regex Validator

The name of the regular expression validator: Regex, he checks whether the field of the checksum is matched by a regular expression

Parameters:

FieldName: This parameter specifies the name of the Action property of the checksum, and if the field checksum style is used, it is not necessary to specify the parameter; expression: Optionally, this parameter specifies a matching regular expression; Casesemsitive: Optionally, this parameter indicates that a regular expression match is case sensitive, default true

Use a non-field validator configuration format, sample configuration:
<validators>
<!--using a non-field validator format; To configure the regular expression Checker-->
<validator type= "Regex" >
<!--Specify a validation field: User-->
<param name= "FieldName" >user</param>
<!--specify a matching regular expression-->
<param name= "expression" ><! [Cdata[(/w{4,20})]]</param>
<!--specify prompt for checksum failure-->
<message> username must be between 4 and 20, and must be a letter or number </message>
</validator>
........................
</validators>

Configure the format with field validators, and configure the example:

<validators>
    <!--Use the field validator format to configure the regular validator to validate the user property;
     <field name= "User"
         <field-validator   type= "Regex"
              <!--specify a matching regular expression;
        <param name= "expression" ><![ cdata[(/w{4,20})]]</param>
        <!--Specify a prompt for validation failures-->
        <message> username must be between 4 and 20, and must be a letter or number </message>
         </field-validator>
          . ...................
    </field>
     .......... ...
</validators>