<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>2.0.1.Final</version>
</dependency>
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
public class StringLengthValidator implements ConstraintValidator<StringLength, String> {
private int min;
private int max;
@Override
public void initialize(StringLength constraintAnnotation) {
this.min = constraintAnnotation.min();
this.max = constraintAnnotation.max();
}
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
if (value == null) {
return true;
}
int length = value.length();
return length >= min && length <= max;
}
}
import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.*;
@Documented
@Constraint(validatedBy = StringLengthValidator.class)
@Target({ElementType.FIELD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface StringLength {
String message() default "Invalid string length";
int min() default 0;
int max() default Integer.MAX_VALUE;
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
public class User {
@StringLength(min = 5, max = 10)
private String username;
}
import org.springframework.context.annotation.Configuration;
import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
@Configuration
public class ValidationConfig {
@Bean
public LocalValidatorFactoryBean validator() {
return new LocalValidatorFactoryBean();
}
}
