Jackson 使用 @JsonValue 枚举类型对属性值进行序列化和反序列化。
最编程
2024-04-15 22:17:01
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一般我们在定义带有枚举类型的api时,通常传入或者返回字符串来进行数据的序列化与反序列化输出。
如下定义:
private StatusEnum status;
但是如果想返回它的自定义属性值, emm.
经过查证可以使用@JsonValue来标记枚举想要返回的序列化值,标记在属性的getter方法上。
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).
*<p>
* At most one accessor of a <code>Class</code> 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).
*<p>
* A typical usage is that of annotating <code>toString()</code>
* 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.
*<p>
* Boolean argument is only used so that sub-classes can "disable"
* annotation if necessary.
*<p>
* NOTE: when use for Java <code>enum</code>s, 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.
*/
boolean value() default true;
}
文字功底不好,就这样自行悟吧。