Andrej Koelewijn

Continuing my example from a few days back, this example shows how to create a JSF validator tag which checks agains a regular expression.

Step 5: custom validator tag

1. Add validator class

   package jsftest1;
   
   import javax.faces.application.FacesMessage;
   import javax.faces.component.UIComponent;
   import javax.faces.context.FacesContext;
   import javax.faces.validator.Validator;
   import javax.faces.validator.ValidatorException;
   
   public class RegExValidator implements
           Validator {
   
       String regex;
   
       public void validate(
               FacesContext _context,
               UIComponent _component,
               Object _value)
               throws ValidatorException {
   
           String val = (String) _value;
           if (!val.matches(regex)) {
               throw new ValidatorException(
                       new FacesMessage(
                               "Incorrect value, does not match regular expression: "
                                       + regex));
           }
   
       }
   
       public String getRegex() {
           return regex;
       }
   
       public void setRegex(String regex) {
           this.regex = regex;
       }
   }
   

2. Add validator tag class

   package jsftest1;
   
   import javax.faces.validator.Validator;
   import javax.faces.webapp.ValidatorTag;
   import javax.servlet.jsp.JspException;
   
   public class RegExValidatorTag extends
           ValidatorTag {
   
       private String regex;
   
       public RegExValidatorTag() {
           super();
           super.setValidatorId("regexValidator");
       }
   
       protected Validator createValidator()
               throws JspException {
           RegExValidator result = null;
           result = (RegExValidator) super.createValidator();
           result.setRegex(regex);
           return result;
       }
   
       public String getRegex() {
           return regex;
       }
   
       public void setRegex(String regex) {
           this.regex = regex;
       }
   }
   

3. Add tag lib descriptor file /web/WEB-INF/jsftest1.tld

   <taglib>
     <tlibversion>0.1</tlibversion>
     <jspversion>2.0</jspversion>
     <shortname>JSF test 1 taglib</shortname>
     <tag>
       <name>regexValidator</name>
       <tagclass>jsftest1.RegExValidatorTag</tagclass>
       <attribute>
         <name>regex</name>
         <required>true</required>
         <rtexprvalue>false</rtexprvalue>
       </attribute>
     </tag>
   </taglib>
   

4. Add validator to faces-config.xml

   <validator>
     <validator-id>regexValidator</validator-id>
     <validator-class>jsftest1.RegExValidator</validator-class>
     <attribute>
       <attribute-name>regex</attribute-name>
       <attribute-class>java.lang.String</attribute-class>
     </attribute>
   </validator>
   

5. Modify jsp page

   <h:outputLabel for="firstName">
     <h:outputText value="#{bundle.firstName}"/>
   </h:outputLabel>
   <h:inputText id="firstName" value="#{registerBean.firstName}" >
     <f:validateLength minimum="1"/>
     <j:regexValidator regex="[A-Z]+"/>
     <f:validator validatorId="registerValidator"/>
   </h:inputText>
   <h:message for="firstName"/>