JSF - Custom Validator

Step No.	Description
1	Create a validator class by implementing javax.faces.validator.Validator interface.
2	Implement validate() method of above interface.
3	Use Annotation @FacesValidator to assign a unique id to the custom validator.

Step 1: Create a validator class : UrlValidator.java

public class UrlValidator implements Validator {
...
}

Step 2: Implement Validator interface methods : UrlValidator.java

public class UrlValidator implements Validator {
   @Override
   public void validate(FacesContext facesContext,
      UIComponent component, String value) throws ValidatorException {
      ...
   }
}

Step 3: Annotate to register the validator : UrlValidator.java

@FacesValidator("com.tutorialspoint.test.UrlValidator")
public class UrlValidator implements Converter {
}

Use the validator in JSF page

<h:inputText id="urlInput" value="#{userData.data}" label="URL" >
   <f:validator validatorId="com.tutorialspoint.test.UrlValidator" />
</h:inputText>

Example Application

Let us create a test JSF application to test the above tag.

Step	Description
1	Create a project with a name helloworld under a package com.tutorialspoint.test as explained in the JSF - First Application chapter.
2	Create UrlValidator.java as a converter under package com.tutorialspoint.test as explained below.
3	Create UserData.java as a managed bean under package com.tutorialspoint.test as explained below.
4	Modify home.xhtml as explained below. Keep rest of the files unchanged.
5	Create result.xhtml in the webapps directory as explained below.
6	Compile and run the application to make sure business logic is working as per the requirements.
7	Finally, build the application in the form of war file and deploy it in Apache Tomcat Webserver.
8	Launch your web application using appropriate URL as explained below in the last step.

UrlValidator.java

package com.tutorialspoint.test;

import java.net.URI;
import java.net.URISyntaxException;

import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.validator.FacesValidator;
import javax.faces.validator.Validator;
import javax.faces.validator.ValidatorException;

@FacesValidator("com.tutorialspoint.test.UrlValidator")
public class UrlValidator implements Validator {

   @Override
   public void validate(FacesContext facesContext, 
      UIComponent component, Object value)
      throws ValidatorException {

      StringBuilder url = new StringBuilder();
      String urlValue = value.toString();

      if(!urlValue.startsWith("http://", 0)){
         url.append("http://");
      }
      url.append(urlValue);

      try {
         new URI(url.toString());	        
      } catch (URISyntaxException e) {
         FacesMessage msg = 
            new FacesMessage("URL validation failed","Invalid URL format");
         msg.setSeverity(FacesMessage.SEVERITY_ERROR);
         throw new ValidatorException(msg);
      } 
   }
}

UserData.java

package com.tutorialspoint.test;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;

@ManagedBean(name = "userData", eager = true)
@SessionScoped
public class UserData implements Serializable {

private static final long serialVersionUID = 1L;

   public String data;

   public String getData() {
      return data;
   }

   public void setData(String data) {
      this.data = data;
   }	
}

home.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
   xmlns:h="http://java.sun.com/jsf/html"
   xmlns:f="http://java.sun.com/jsf/core">
   <h:head>
      <title>JSF tutorial</title>			
   </h:head>
   <h:body>
      <h2>Custom Validator Example</h2>
      <h:form>
         <h:inputText id="urlInput" value="#{userData.data}" 
            label="URL" >
            <f:validator validatorId="com.tutorialspoint.test.UrlValidator" />
         </h:inputText>		 
         <h:commandButton value="submit" action="result"/>
         <h:message for="urlInput" style="color:red" />
      </h:form>
   </h:body>
</html>

result.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
   xmlns:f="http://java.sun.com/jsf/core"    
   xmlns:h="http://java.sun.com/jsf/html"
   xmlns:ui="http://java.sun.com/jsf/facelets">
   <h:body>
      <h2>Result</h2>
      <hr />
      #{userData.data}   	
   </h:body>
</html>

Once you are ready with all the changes done, let us compile and run the application as we did in JSF - First Application chapter. If everything is fine with your application, this will produce following result:

Enter any invalid value and press submit button.See the error message.

Enter any valid value and press submit button.See the result.

Print Version

PDF Version

Tutorials Point - Simply Easy Learning