@Documented
@Target(value=ANNOTATION_TYPE)
@Retention(value=RUNTIME)
public @interface Constraint
A given constraint annotation must be annotated by a @Constraint
annotation which refers to its list of constraint validation implementations.
Each constraint annotation must host the following attributes:
String message() default [...];
which should default to an error
message key made of the fully-qualified class name of the constraint followed by
.message
. For example "{com.acme.constraints.NotSafe.message}"
Class<?>[] groups() default {};
for user to customize the targeted
groupsClass<? extends Payload>[] payload() default {};
for
extensibility purposes
When building a constraint that is both generic and cross-parameter, the constraint
annotation must host the validationAppliesTo()
property.
A constraint is generic if it targets the annotated element and is cross-parameter if
it targets the array of parameters of a method or constructor.
ConstraintTarget validationAppliesTo() default ConstraintTarget.IMPLICIT;This property allows the constraint user to choose whether the constraint targets the return type of the executable or its array of parameters. A constraint is both generic and cross-parameter if
ConstraintValidator
s are attached to the
constraint, one targeting ValidationTarget.ANNOTATED_ELEMENT
and one targeting ValidationTarget.PARAMETERS
,ConstraintValidator
targets both
ANNOTATED_ELEMENT
and PARAMETERS
.SupportedValidationTarget
for more info.
Here is an example of constraint definition:
@Documented @Constraint(validatedBy = OrderNumberValidator.class) @Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE }) @Retention(RUNTIME) public @interface OrderNumber { String message() default "{com.acme.constraint.OrderNumber.message}"; Class<?>[] groups() default {}; Class<? extends Payload>[] payload() default {}; }
Modifier and Type | Required Element and Description |
---|---|
java.lang.Class<? extends ConstraintValidator<?,?>>[] |
validatedBy
ConstraintValidator classes implementing the constraint. |
public abstract java.lang.Class<? extends ConstraintValidator<?,?>>[] validatedBy
ConstraintValidator
classes implementing the constraint. The given classes
must reference distinct target types for a given ValidationTarget
. If two
ConstraintValidator
s refer to the same type, an exception will occur.
At most one ConstraintValidator
targeting the array of parameters of
methods or constructors (aka cross-parameter) is accepted. If two or more
are present, an exception will occur.
ConstraintValidator
classes implementing the constraint