Features for configuring Java-to-JSON mapping
Following on/off features are defined in SerializationConfig.Feature:
USE_ANNOTATIONS (default: true) (since 1.2)
Controls whether any annotation introspection is used for configuring data binding: if disabled, all annotations are ignored (independent of setting for AnnotationIntrospector in use)
note: since 1.8, disable this feature will try to remove ALL annotation processing; this to help on platforms like Android, where trying to access unavailable annotation types (JAXB annotations for value types) can result in exception, even if not specifically looking for that annotation type.
- AUTO_DETECT_GETTERS (default: true)
Controls whether "getter" methods are automatically detected (as opposed to located by annotations); if enabled, public no-argument non-static no-argument methods are recognized as getters. If disabled, only ones explicitly annotated (using @JsonProperty, for example) are recognized as serializable properties
- AUTO_DETECT_IS_GETTERS (default: true)
Controls whether "is-getter" methods (methods with name "isXxx()" that return boolean or java.lang.Boolean value) are automatically detected (as opposed to located by annotations); if enabled, such methods are detected as getters. If disabled, only ones explicitly annotated (using @JsonProperty, for example) are recognized as serializable properties
- AUTO_DETECT_FIELDS (default: true)
- Similar to above, controls whether public instance fields are recognized as serializable properties.
- REQUIRE_SETTERS_FOR_GETTERS (default: false)
- Controls whether auto-detection of getter methods requires presence of mutators (setter / constructor argument / field) to include auto-detectable getters or not: if enabled, only getters with matching mutator are included via auto-detection (meaning: explicitly annotated getters are still included); if disabled, all auto-detectable getters are included.
- NOTE: some frameworks such as JAXB behave as if this feature was enabled; and enabling it can help ensure that serialized JSON can be deserialized back -- conversely, for write-only use cases, this feature is usually best left disabled.
- Controls whether auto-detection of getter methods requires presence of mutators (setter / constructor argument / field) to include auto-detectable getters or not: if enabled, only getters with matching mutator are included via auto-detection (meaning: explicitly annotated getters are still included); if disabled, all auto-detectable getters are included.
- CAN_OVERRIDE_ACCESS_MODIFIERS(default: true)
- Whether non-public fields and methods can be forced accessible (using JDK provided methods or not): if disabled, non-public fields and methods can not be used for properties. The main reason to disable this feature is if running on a security-restricted platform where trying to change access rights results in a runtime error.
- USE_STATIC_TYPING (default: false)
- Controls whether the type detection for serialization should be using actual dynamic runtime type or declared static type. Default value is false, to use dynamic runtime type.
This global default value can be overridden at class, or method/field level by using JsonSerialize annotation (its typing property)
- Controls whether the type detection for serialization should be using actual dynamic runtime type or declared static type. Default value is false, to use dynamic runtime type.
- WRITE_DATES_AS_TIMESTAMPS(default: true)
Controls whether Date / Time values are to be written out as numeric (64-bit) timestamps (if true) or as Strings. If latter, format used is defined by SerializationConfig.getDateFormat
- INDENT_OUTPUT (default: false)
- Controls whether output is indented using the default indentation ("pretty-printing") mechanism (2-space, platform linefeeds) or not.
SORT_PROPERTIES_ALPHABETICALLY (default: false) (since 1.8)
Controls default ordering used for serializing POJO fields (note: does NOT apply to Maps!): if enabled, default ordering is alphabetic (similar to how @JsonPropertyOrder.alphabetic=true works; if disabled, default order is unspecified.
- Note that explicit ordering annotations on type (class) override default settings.
FAIL_ON_EMPTY_BEANS (default: true) (since 1.4)
Controls whether exception is thrown if no serializer is found for a type (Class); and type has neither getters nor recognized annotations (ones configured AnnotationIntrospector recognizes, including JacksonJAXBAnnotations if JAXB introspector used). If enabled, exception is thrown; if disabled, will just output empty JSON Object.
DEFAULT_VIEW_INCLUSION (default: true) (since 1.5)
Controls what is the behavior of properties that have no matching JsonView annotation: if set to true, they are included in all views; if false, not included in any views. This only affects JSON View enabled processing (i.e. when Serialization View is specified)
CLOSE_CLOSEABLE (default: false) (since 1.6)
If enabled, ObjectMapper will call close() and root values that implement java.io.Closeable; including cases where exception is thrown and serialization does not completely succeed.
Can be useful for resource clean up; and specifically allows for building wrappers that can be useful when serializing referential values (like, say, serializing a java.io.File value by reading contents of a file and outputting as JSON String or base64-encoded binary)
WRITE_CHAR_ARRAYS_AS_JSON_ARRAYS (default: false) (since 1.6)
Controls how basic char[] values are serialized: if enabled, they will be serialized as full JSON Arrays, with JSON Strings (of length 1 character) as elements; if disabled (which is the default) as a single JSON String consisting of all characters of the array.
WRITE_ENUMS_USING_TO_STRING (default: false) (since 1.6)
Determines which method is used to determine expected serialization of an Enum (when serialized as String): if false (default), use Enum.name(); if true, Enum.toString().
WRITE_ENUMS_USING_INDEX (default: false) (since 1.9)
Determines whether Enums are to be serialized as integers (true), or Strings (false): if integers, Enum.ordinal() value is used as serialization.
WRITE_NULL_MAP_VALUES (default: true) (since 1.6)
- Determines whether Map entries with value null are serialized or not.
WRAP_ROOT_VALUE(default: false) (since 1.7): When enabled, will wrap output in a single-property JSON Object. Name of wrapper property is based on class name of the serialized instance (or value type if static typing used or root type specified); or, if using JAXB annotations, name from @XmlRootElement.
FLUSH_AFTER_WRITE_VALUE (default: true) (since 1.7)
Determines whether JsonGenerator.flush() is automatically called after ObjectMapper's writeValue(JsonGenerator, ...) is called or not (note: does NOT affect methods that do not take JsonGenerator) -- if true flush() is called; if false, it is not called.
- Main reason to disable this feature is performance; for network connections flushing may send message earlier than optimal, and with some compressing streams compression block may complete with flush().
WRITE_EMPTY_JSON_ARRAYS (default: true) (since 1.9), to allow suppressing serialization of empty Collections/arrays.
Deprecated features
Additionally there are deprecated legacy features that still work but will removed from API in future:
WRITE_NULL_PROPERTIES(default: true) (NOTE: deprecated as of 1.1)
- Controls where values of properties that have null as value are written out or not.
Does NOT work for Maps; see WRITE_NULL_MAP_VALUES.
deprecated Use SerializationConfig#setSerializationInclusion instead