LocalValidatorFactoryBean implements both javax.validation.Validator and org.springframework.validation.Validator. You may inject a reference to one of these two interfaces into beans that need to invoke validation logic.

Inject a reference to javax.validation.Validator if you prefer to work with the JSR-303 API directly:

import javax.validation.Validator;

@Service
public class MyService {

    @Autowired
    private Validator validator;

Inject a reference to org.springframework.validation.Validator if your bean requires the Spring Validation API:

import org.springframework.validation.Validator;

@Service
public class MyService {

    @Autowired
    private Validator validator;

}

Each JSR-303 validation constraint consists of two parts. First, a @Constraint annotation that declares the constraint and its configurable properties. Second, an implementation of the javax.validation.ConstraintValidator interface that implements the constraint's behavior. To associate a declaration with an implementation, each @Constraint annotation references a corresponding ValidationConstraint implementation class. At runtime, a ConstraintValidatorFactory instantiates the referenced implementation when the constraint annotation is encountered in your domain model.

By default, the LocalValidatorFactoryBean configures a SpringConstraintValidatorFactory that uses Spring to create ConstraintValidator instances. This allows your custom ConstraintValidators to benefit from dependency injection like any other Spring bean.

Shown below is an example of a custom @Constraint declaration, followed by an associated ConstraintValidator implementation that uses Spring for dependency injection:

@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy=MyConstraintValidator.class)
public @interface MyConstraint {
}

import javax.validation.ConstraintValidator;

public class MyConstraintValidator implements ConstraintValidator {

    @Autowired;
    private Foo aDependency;

    ...
}

As you can see, a ConstraintValidator implementation may have its dependencies @Autowired like any other Spring bean.

The default LocalValidatorFactoryBean configuration should prove sufficient for most cases. There are a number of other configuration options for various JSR-303 constructs, from message interpolation to traversal resolution. See the JavaDocs of LocalValidatorFactoryBean more information on these options.

To trigger validation of a @Controller input, simply annotate the input argument as @Valid:

@Controller
public class MyController {

    @RequestMapping("/foo", method=RequestMethod.POST)
    public void processFoo(@Valid Foo foo) { /* ... */ }

Spring MVC will validate a @Valid object after binding so-long as an appropriate Validator has been configured.

	Note
	The @Valid annotation is part of the standard JSR-303 Bean Validation API, and is not a Spring-specific construct.

The Validator instance invoked when a @Valid method argument is encountered may be configured in two ways. First, you may call binder.setValidator(Validator) within a @Controller's @InitBinder callback. This allows you to configure a Validator instance per @Controller class:

@Controller
public class MyController {

    @InitBinder
    protected void initBinder(WebDataBinder binder) {
        binder.setValidator(new FooValidator());
    }
    
    @RequestMapping("/foo", method=RequestMethod.POST)
    public void processFoo(@Valid Foo foo) { ... }
	
}

Second, you may call setValidator(Validator) on the global WebBindingInitializer. This allows you to configure a Validator instance across all @Controllers. This can be achieved easily by using the Spring MVC namespace:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <mvc:annotation-driven validator="globalValidator"/>
    
</beans>

				

With JSR-303, a single javax.validation.Validator instance typically validates all model objects that declare validation constraints. To configure a JSR-303-backed Validator with Spring MVC, simply add a JSR-303 Provider, such as Hibernate Validator, to your classpath. Spring MVC will detect it and automatically enable JSR-303 support across all Controllers.

The Spring MVC configuration required to enable JSR-303 support is shown below:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <!-- JSR-303 support will be detected on classpath and enabled automatically -->
    <mvc:annotation-driven/>
    
</beans>

				

With this minimal configuration, anytime a @Valid @Controller input is encountered, it will be validated by the JSR-303 provider. JSR-303, in turn, will enforce any constraints declared against the input. Any ConstaintViolations will automatically be exposed as errors in the BindingResult renderable by standard Spring MVC form tags.