Why Jackson create each Serializer/Deserializer instance for @JsonSerializer/@JsonDeserializer annotated class

[Dongkwon Lee]

I don't know well , Post a question.

I used Jackson Json Libraries with SpringBoot

When i use @JsonSerialize(using = CustomSerializer.class) in severals DTO class Field

CustomSerializer has no-args constructor with "initialized" logging command

    public class CustomSerializer extends JsonSerializer<String> {

        public CustomSerializer() {
            super();
            log.info("initialize : {}", this);
        }
    
        @Override
        public void serialize(String value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
            gen.writeString("Custom-" + value);
        }

    }

Jackson create Serializer instance for Each DTO class on Json Serialize Process.

how can i create Serializer single instance, and share this.

is it right thinking?

[이동권]

I don't know well, Post a question.

I used Jackson Json Libraries with SpringBoot

When i use @JsonSerialize(using = CustomSerializer.class) in severals POJO class Field

CustomSerializer has no-args constructor with "initialized" logging command

Jackson create Serializer instance for Each POJO class on Json Serialize Process.

how can i create Serializer single instance, and share this.

is it right thinking?

[Tatu Saloranta]

On Fri, Jul 10, 2020 at 8:29 PM 이동권 <circ...@gmail.com> wrote:
>
>
> I don't know well, Post a question.
> I used Jackson Json Libraries with SpringBoot
>
> When i use @JsonSerialize(using = CustomSerializer.class) in severals POJO class Field
>
> CustomSerializer has no-args constructor with "initialized" logging command
> Jackson create Serializer instance for Each POJO class on Json Serialize Process.
>
> how can i create Serializer single instance, and share this.
>
> is it right thinking?

When using `JsonSerializer(using = )`, a new instance will be created
for every POJO type, correct.

If you would like to use one serializer instance for multiple types,
you should instead register serializers using `Module`.
For example, using `SimpleModule`:

-----
SimpleModule module = new SimpleModule();
module.addSerializer(Type1.class, serializerInstance);
module.addSerializer(Type2.class, serializerInstance);
ObjectMapper mapper = JsonMapper.builder().
.addModule(module)
.build();
-----

I hope this helps

-+Tatu +-