Hibernate is a powerful tool for Java developers that allows them to map Java
classes to database tables. One of the many features of Hibernate is the
ability to validate data before it is persisted to the database. Email
validation is a common requirement for many applications, and Hibernate
provides a number of ways to validate email addresses.

Using Hibernate Validator

Hibernate Validator is a powerful validation framework that can be used to
validate data in Hibernate applications. It provides a number of built-in
validators, including an email validator.

The email validator in Hibernate Validator is implemented using the
javax.validation.constraints.Email annotation. This annotation can be added to
a property in a Hibernate entity to validate that the value of the property is
a valid email address.

Example:

@Entity public class User { @Id @GeneratedValue private Long id; @Email private String email; }

In this example, the email property of the User entity is annotated with the
@Email annotation. This will cause Hibernate Validator to validate that the
value of the email property is a valid email address.

Custom Email Validator

Sometimes, the built-in email validator in Hibernate Validator may not be
suitable for your specific needs. In this case, you can create your own custom
email validator by implementing the
org.hibernate.validator.constraintvalidators.EmailValidator interface.

The EmailValidator interface has a single method, isValid(), which takes two
parameters: the value to be validated and a ConstraintValidatorContext object.
The isValid() method should return true if the value is valid, and false
otherwise.

Example:

public class CustomEmailValidator implements EmailValidator { public void initialize(Email constraintAnnotation) { } public boolean isValid(String value, ConstraintValidatorContext context) { // Custom email validation logic goes here } }

In this example, we have created a custom email validator by implementing the
EmailValidator interface. The isValid() method contains our custom email
validation logic.

Conclusion

Email validation is an important requirement for many applications, and
Hibernate provides a number of ways to validate email addresses. The built-in
email validator in Hibernate Validator is a powerful tool that can be used to
validate email addresses in Hibernate entities. If the built-in validator is
not suitable for your specific needs, you can create a custom email validator
by implementing the EmailValidator interface.