How Can I Configure Jackson to Use Only Fields for Serialization and Deserialization?

Configuring Jackson to Use Fields Only for Serialization and Deserialization

Jackson's default behavior involves using both properties (getters and setters) and fields for serialization and deserialization to JSON. However, some users may prefer to prioritize fields as the sole source of serialization configuration, excluding properties.

Annotation-based Approach for Individual Classes

To enforce this behavior on a per-class basis, the @JsonAutoDetect annotation can be used:

@JsonAutoDetect(fieldVisibility = Visibility.ANY, getterVisibility = Visibility.NONE, setterVisibility = Visibility.NONE)

This annotation excludes properties from Jackson's consideration, ensuring that only fields are used for data binding.

Global Configuration for All Classes

Instead of applying the annotation to each class manually, it is possible to configure this behavior globally for all classes. To achieve this, the ObjectMapper needs to be modified as follows:

ObjectMapper mapper  = new ObjectMapper();
mapper.setVisibility(mapper.getSerializationConfig().getDefaultVisibilityChecker()
                .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
                .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withCreatorVisibility(JsonAutoDetect.Visibility.NONE));

This configuration overrides the default visibility settings and instructs Jackson to use only fields for serialization and deserialization across all classes.

Accessing the Configured Mapper Globally

For global access to the configured ObjectMapper, a wrapper class can be used:

public class MyGlobalMapper {
    private static final ObjectMapper MAPPER = new ObjectMapper();

    static {
        MAPPER.setVisibility(MAPPER.getSerializationConfig().getDefaultVisibilityChecker()
                .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
                .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withCreatorVisibility(JsonAutoDetect.Visibility.NONE));
    }

    public static ObjectMapper get() {
        return MAPPER;
    }
}

This wrapper class provides a static method to retrieve the configured ObjectMapper, allowing it to be used throughout the application without the need to reconfigure it each time.

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