Form input constraints not being enforced?

I'm new to Tomcat and Spring Web. I'm trying to use Spring's form validation features by following this tutorial. Everything seems to run smoothly except for one thing... my form doesn't do any validation and I can always get to the success page when I send the form no matter which data I provide.

Am I using the constraints correctly? I want to enforce that the user fills in their first name and that the first name be at least two characters long.

package net.devmanuals.form;

import javax.validation.constraints.Size;
import org.hibernate.validator.constraints.NotEmpty;

public class RegistrationForm {
    @NotEmpty(message = "You surely have a name, don't you?")
    @Size(min = 2, message = "I'm pretty sure that your name consists of more than one letter.")
    private String firstName;

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getFirstName() {
        return this.firstName;
    }
}

Form code:

    <form:form method="post" commandName="regform">
        <p><form:input path="firstName" /> <form:errors path="firstName" /></p>
        <p><input type="submit" /></p>
    </form:form>

The controller:

@Controller
@RequestMapping("/register")
public class RegistrationController {
    @RequestMapping(method = RequestMethod.GET)
    public String showRegForm(Map model) {
        RegistrationForm regForm = new RegistrationForm();
        model.put("regform", regForm);
  开发者_运维问答      return "regform";
    }

    @RequestMapping(method = RequestMethod.POST)
    public String validateForm(@Valid RegistrationForm regForm, BindingResult result, Map model) {
        if (result.hasErrors()) {
            return "regform";
        }

        model.put("regform", regForm);
        return "regsuccess";
    }
}

Am I applying the constraints incorrectly?

In addition to adding <mvc:annotation-driven/> to your config, you need to make sure the JSR-303 jar is on your classpath. From the docs:

[AnnotationDrivenBeanDefinitionParser] ... configures the validator if specified, otherwise defaults to a fresh Validator instance created by the default LocalValidatorFactoryBean if the JSR-303 API is present on the classpath.