com.fasterxml.jackson.annotation.JsonValue Maven / Gradle / Ivy
/*
* Copyright © 2019 Dominokit
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.fasterxml.jackson.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Marker annotation that indicates that the value of annotated accessor (either field or "getter"
* method [a method with non-void return type, no args]) is to be used as the single value to
* serialize for the instance, instead of the usual method of collecting properties of value.
* Usually value will be of a simple scalar type (String or Number), but it can be any serializable
* type (Collection, Map or Bean).
*
* At most one accessor of a Class can be annotated with this annotation; if more
* than one is found, an exception may be thrown. Also, if method signature of annotated method is
* not compatible with Getters, an exception may be thrown (whether exception is thrown or not is an
* implementation detail (due to filtering during introspection, some annotations may be skipped)
* and applications should not rely on specific behavior).
*
*
A typical usage is that of annotating toString() method so that returned String
* value is used as the JSON serialization; and if deserialization is needed, there is matching
* constructor or factory method annotated with {@link JsonCreator} annotation.
*
*
Boolean argument is only used so that sub-classes can "disable" annotation if necessary.
*
*
NOTE: when use for Java enums, one additional feature is that value returned by
* annotated method is also considered to be the value to deserialize from, not just JSON String to
* serialize as. This is possible since set of Enum values is constant and it is possible to define
* mapping, but can not be done in general for POJO types; as such, this is not used for POJO
* deserialization.
*
* @see JsonCreator
*/
@Target({
ElementType.ANNOTATION_TYPE,
ElementType.METHOD,
ElementType.FIELD // since 2.9
})
@Retention(RetentionPolicy.RUNTIME)
@JacksonAnnotation
public @interface JsonValue {
/**
* Optional argument that defines whether this annotation is active or not. The only use for value
* 'false' if for overriding purposes. Overriding may be necessary when used with "mix-in
* annotations" (aka "annotation overrides"). For most cases, however, default value of "true" is
* just fine and should be omitted.
*
* @return boolean
*/
boolean value() default true;
}