Jackson Annotations Source Code

Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Annotations Source Code files are provided in the source packge (jackson-annotations-2.12.4-sources.jar). You can download it at Jackson Maven Website.

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com/fasterxml/jackson/databind/MapperFeature.java

package com.fasterxml.jackson.databind;

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.fasterxml.jackson.databind.cfg.ConfigFeature;

/**
 * Enumeration that defines simple on/off features to set
 * for {@link ObjectMapper}, and accessible (but not changeable)
 * via {@link ObjectReader} and {@link ObjectWriter} (as well as
 * through various convenience methods through context objects).
 *<p>
 * Note that in addition to being only mutable via {@link ObjectMapper},
 * changes only take effect when done <b>before any serialization or
 * deserialization</b> calls -- that is, caller must follow
 * "configure-then-use" pattern.
 */
public enum MapperFeature implements ConfigFeature
{
    /*
    /******************************************************
    /* General introspection features
    /******************************************************
     */

    /**
     * Feature that determines whether annotation introspection
     * is used for configuration; if enabled, configured
     * {@link AnnotationIntrospector} will be used: if disabled,
     * no annotations are considered.
     *<p>
     * Feature is enabled by default.
     */
    USE_ANNOTATIONS(true),

    /**
     * Feature that determines whether otherwise regular "getter"
     * methods (but only ones that handle Collections and Maps,
     * not getters of other type)
     * can be used for purpose of getting a reference to a Collection
     * and Map to modify the property, without requiring a setter
     * method.
     * This is similar to how JAXB framework sets Collections and
     * Maps: no setter is involved, just setter.
     *<p>
     * Note that such getters-as-setters methods have lower
     * precedence than setters, so they are only used if no
     * setter is found for the Map/Collection property.
     *<p>
     * Feature is enabled by default.
     */
    USE_GETTERS_AS_SETTERS(true),

    /**
     * Feature that determines how <code>transient</code> modifier for fields
     * is handled: if disabled, it is only taken to mean exclusion of the field
     * as accessor; if true, it is taken to imply removal of the whole property.
     *<p>
     * Feature is disabled by default, meaning that existence of `transient`
     * for a field does not necessarily lead to ignoral of getters or setters
     * but just ignoring the use of field for access.
     *
     * @since 2.6
     */
    PROPAGATE_TRANSIENT_MARKER(false),

    /*
    /******************************************************
    /* Introspection-based property auto-detection
    /******************************************************
     */

    /**
     * Feature that determines whether "creator" methods are
     * automatically detected by consider public constructors,
     * and static single argument methods with name "valueOf".
     * If disabled, only methods explicitly annotated are considered
     * creator methods (except for the no-arg default constructor which
     * is always considered a factory method).
     *<p>
     * Note that this feature has lower precedence than per-class
     * annotations, and is only used if there isn't more granular
     * configuration available.
     *<P>
     * Feature is enabled by default.
     */
    AUTO_DETECT_CREATORS(true),
    
    /**
     * Feature that determines whether non-static fields are recognized as
     * properties.
     * If yes, then all public member fields
     * are considered as properties. If disabled, only fields explicitly
     * annotated are considered property fields.
     *<p>
     * Note that this feature has lower precedence than per-class
     * annotations, and is only used if there isn't more granular
     * configuration available.
     *<p>
     * Feature is enabled by default.
     */
    AUTO_DETECT_FIELDS(true),
    
    /**
     * Feature that determines whether regular "getter" methods are
     * automatically detected based on standard Bean naming convention
     * or not. If yes, then all public zero-argument methods that
     * start with prefix "get" 
     * are considered as getters.
     * If disabled, only methods explicitly  annotated are considered getters.
     *<p>
     * Note that since version 1.3, this does <b>NOT</b> include
     * "is getters" (see {@link #AUTO_DETECT_IS_GETTERS} for details)
     *<p>
     * Note that this feature has lower precedence than per-class
     * annotations, and is only used if there isn't more granular
     * configuration available.
     *<p>
     * Feature is enabled by default.
     */
    AUTO_DETECT_GETTERS(true),

    /**
     * Feature that determines whether "is getter" methods are
     * automatically detected based on standard Bean naming convention
     * or not. If yes, then all public zero-argument methods that
     * start with prefix "is", and whose return type is boolean
     * are considered as "is getters".
     * If disabled, only methods explicitly annotated are considered getters.
     *<p>
     * Note that this feature has lower precedence than per-class
     * annotations, and is only used if there isn't more granular
     * configuration available.
     *<p>
     * Feature is enabled by default.
     */
    AUTO_DETECT_IS_GETTERS(true),

    /**
     * Feature that determines whether "setter" methods are
     * automatically detected based on standard Bean naming convention
     * or not. If yes, then all public one-argument methods that
     * start with prefix "set"
     * are considered setters. If disabled, only methods explicitly
     * annotated are considered setters.
     *<p>
     * Note that this feature has lower precedence than per-class
     * annotations, and is only used if there isn't more granular
     * configuration available.
     *<P>
     * Feature is enabled by default.
     */
    AUTO_DETECT_SETTERS(true),

    /**
     * Feature that determines whether getters (getter methods)
     * can be auto-detected if there is no matching mutator (setter,
     * constructor parameter or field) or not: if set to true,
     * only getters that match a mutator are auto-discovered; if
     * false, all auto-detectable getters can be discovered.
     *<p>
     * Feature is disabled by default.
     */
    REQUIRE_SETTERS_FOR_GETTERS(false),

    /**
     * Feature that determines whether member fields declared as 'final' may
     * be auto-detected to be used mutators (used to change value of the logical
     * property) or not. If enabled, 'final' access modifier has no effect, and
     * such fields may be detected according to usual visibility and inference
     * rules; if disabled, such fields are NOT used as mutators except if
     * explicitly annotated for such use.
     *<p>
     * Feature is enabled by default, for backwards compatibility reasons.
     *
     * @since 2.2
     */
    ALLOW_FINAL_FIELDS_AS_MUTATORS(true),

    /**
     * Feature that determines whether member mutators (fields and
     * setters) may be "pulled in" even if they are not visible,
     * as long as there is a visible accessor (getter or field) with same name.
     * For example: field "value" may be inferred as mutator,
     * if there is visible or explicitly marked getter "getValue()".
     * If enabled, inferring is enabled; otherwise (disabled) only visible and
     * explicitly annotated accessors are ever used.
     *<p>
     * Note that 'getters' are never inferred and need to be either visible (including
     * bean-style naming) or explicitly annotated.
     *<p>
     * Feature is enabled by default.
     *
     * @since 2.2
     */
    INFER_PROPERTY_MUTATORS(true),

    /**
     * Feature that determines handling of {@code java.beans.ConstructorProperties}
     * annotation: when enabled, it is considered as alias of
     * {@link com.fasterxml.jackson.annotation.JsonCreator}, to mean that constructor
     * should be considered a property-based Creator; when disabled, only constructor
     * parameter name information is used, but constructor is NOT considered an explicit
     * Creator (although may be discovered as one using other annotations or heuristics).
     *<p>
     * Feature is mostly used to help inter-operability with frameworks like Lombok
     * that may automatically generate {@code ConstructorProperties} annotation
     * but without necessarily meaning that constructor should be used as Creator
     * for deserialization.
     *<p>
     * Feature is enabled by default.
     *
     * @since 2.9
     */
    INFER_CREATOR_FROM_CONSTRUCTOR_PROPERTIES(true),

    /**
     * Feature that determines whether nominal property type of {@link Void} is
     * allowed for Getter methods to indicate {@code null} valued pseudo-property
     * or not. If enabled, such properties are recognized (see [databind#2675] for
     * reasons -- mostly things related to frameworks, code generation); if disabled,
     * such property accessors (or at least getters) are ignored.
     *<p>
     * Feature is disabled by default (in 2.12) for backwards compatibility.
     *
     * @since 2.12
     */
    ALLOW_VOID_VALUED_PROPERTIES(false),

    /*
    /******************************************************
    /* Access modifier handling
    /******************************************************
     */

    /**
     * Feature that determines whether method and field access
     * modifier settings can be overridden when accessing
     * properties. If enabled, method
     * {@link java.lang.reflect.AccessibleObject#setAccessible}
     * may be called to enable access to otherwise unaccessible objects.
     *<p>
     * Note that this setting may have significant performance implications,
     * since access override helps remove costly access checks on each
     * and every Reflection access. If you are considering disabling
     * this feature, be sure to verify performance consequences if usage
     * is performance sensitive.
     * Also note that performance effects vary between Java platforms
     * (JavaSE vs Android, for example), as well as JDK versions: older
     * versions seemed to have more significant performance difference.
     *<p>
     * Conversely, on some platforms, it may be necessary to disable this feature
     * as platform does not allow such calls. For example, when developing
     * Applets (or other Java code that runs on tightly restricted sandbox),
     * it may be necessary to disable the feature regardless of performance effects.
     *<p>
     * Feature is enabled by default.
     */
    CAN_OVERRIDE_ACCESS_MODIFIERS(true),

    /**
     * Feature that determines that forces call to
     * {@link java.lang.reflect.AccessibleObject#setAccessible} even for
     * <code>public</code> accessors -- that is, even if no such call is
     * needed from functionality perspective -- if call is allowed
     * (that is, {@link #CAN_OVERRIDE_ACCESS_MODIFIERS} is set to true).
     * The main reason to enable this feature is possible performance
     * improvement as JDK does not have to perform access checks; these
     * checks are otherwise made for all accessors, including public ones,
     * and may result in slower Reflection calls. Exact impact (if any)
     * depends on Java platform (Java SE, Android) as well as JDK version.
     *<p>
     * Feature is enabled by default, for legacy reasons (it was the behavior
     * until 2.6)
     *
     * @since 2.7
     */
    OVERRIDE_PUBLIC_ACCESS_MODIFIERS(true),

    /*
    /******************************************************
    /* Type-handling features
    /******************************************************
     */

    /**
     * Feature that determines whether the type detection for
     * serialization should be using actual dynamic runtime type,
     * or declared static type.
     * Note that deserialization always uses declared static types
     * since no runtime types are available (as we are creating
     * instances after using type information).
     *<p>
     * This global default value can be overridden at class, method
     * or field level by using {@link JsonSerialize#typing} annotation
     * property.
     *<p>
     * Feature is disabled by default which means that dynamic runtime types
     * are used (instead of declared static types) for serialization.
     */
    USE_STATIC_TYPING(false),

    /**
     * Feature that specifies whether the declared base type of a polymorphic value
     * is to be used as the "default" implementation, if no explicit default class
     * is specified via {@code @JsonTypeInfo.defaultImpl} annotation.
     *<p>
     * Note that feature only has effect on deserialization of regular polymorphic properties:
     * it does NOT affect non-polymorphic cases, and is unlikely to work with Default Typing.
     *<p>
     * Feature is disabled by default for backwards compatibility.
     *
     * @since 2.10
     */
    USE_BASE_TYPE_AS_DEFAULT_IMPL(false),

    /**
     * Feature that enables inferring builder type bindings from the value type
     * being deserialized. This requires that the generic type declaration on
     * the value type match that on the builder exactly: mismatched type declarations
     * are not necessarily detected by databind.
     *<p>
     * Feature is enabled by default which means that deserialization does
     * support deserializing types via builders with type parameters (generic types).
     *<p>
     * See: https://github.com/FasterXML/jackson-databind/issues/921
     *
     * @since 2.12
     */
    INFER_BUILDER_TYPE_BINDINGS(true),

    /*
    /******************************************************
    /* View-related features
    /******************************************************
     */
    
    /**
     * Feature that determines whether properties that have no view
     * annotations are included in JSON serialization views (see
     * {@link com.fasterxml.jackson.annotation.JsonView} for more
     * details on JSON Views).
     * If enabled, non-annotated properties will be included;
     * when disabled, they will be excluded. So this feature
     * changes between "opt-in" (feature disabled) and
     * "opt-out" (feature enabled) modes.
     *<p>
     * Default value is enabled, meaning that non-annotated
     * properties are included in all views if there is no
     * {@link com.fasterxml.jackson.annotation.JsonView} annotation.
     *<p>
     * Feature is enabled by default.
     */
    DEFAULT_VIEW_INCLUSION(true),
    
    /*
    /******************************************************
    /* Generic output features
    /******************************************************
     */

    /**
     * Feature that defines default property serialization order used
     * for POJO properties.
     * If enabled, default ordering is alphabetic (similar to
     * how {@link com.fasterxml.jackson.annotation.JsonPropertyOrder#alphabetic()}
     * works); if disabled, order is unspecified (based on what JDK gives
     * us, which may be declaration order, but is not guaranteed).
     *<p>
     * Note that this is just the default behavior, and can be overridden by
     * explicit overrides in classes (for example with
     * {@link com.fasterxml.jackson.annotation.JsonPropertyOrder} annotation)
     *<p>
     * Note: does <b>not</b> apply to {@link java.util.Map} serialization (since
     * entries are not considered Bean/POJO properties.
     *<p>
     * Feature is disabled by default.
     */
    SORT_PROPERTIES_ALPHABETICALLY(false),

    /**
     * Feature that defines whether Creator properties (ones passed through
     * constructor or static factory method) should be sorted before other properties
     * for which no explicit order is specified, in case where alphabetic
     * ordering is to be used for such properties.
     * Note that in either case explicit order (whether by name or by index)
     * will have precedence over this setting.
     *<p>
     * Note: does <b>not</b> apply to {@link java.util.Map} serialization (since
     * entries are not considered Bean/POJO properties.
     *<p>
     * Feature is enabled by default.
     *
     * @since 2.12
     */
    SORT_CREATOR_PROPERTIES_FIRST(true),

    /*
    /******************************************************
    /* Name-related features
    /******************************************************
     */

    /**
     * Feature that will allow for more forgiving deserialization of incoming JSON.
     * If enabled, the bean properties will be matched using their lower-case equivalents,
     * meaning that any case-combination (incoming and matching names are canonicalized
     * by lower-casing) should work.
     *<p>
     * Note that there is additional performance overhead since incoming property
     * names need to be lower-cased before comparison, for cases where there are upper-case
     * letters. Overhead for names that are already lower-case should be negligible.
     *<p>
     * Feature is disabled by default.
     * 
     * @since 2.5
     */
    ACCEPT_CASE_INSENSITIVE_PROPERTIES(false),


    /**
     * Feature that determines if Enum deserialization should be case sensitive or not.
     * If enabled, Enum deserialization will ignore case, that is, case of incoming String
     * value and enum id (depending on other settings, either `name()`, `toString()`, or
     * explicit override) do not need to match.
     *<p>
     * This should allow both Enum-as-value deserialization and Enum-as-Map-key, but latter
     * only works since Jackson 2.12 (due to incomplete implementation).
     *<p>
     * Feature is disabled by default.
     *
     * @since 2.9
     */
    ACCEPT_CASE_INSENSITIVE_ENUMS(false),

    /**
     * Feature that permits parsing some enumerated text-based value types but ignoring the case
     * of the values on deserialization: for example, date/time type deserializers.
     * Support for this feature depends on deserializer implementations using it.
     *<p>
     * Note, however, that regular {@code Enum} types follow {@link #ACCEPT_CASE_INSENSITIVE_ENUMS}
     * setting instead.
     *<p>
     * Feature is disabled by default.
     * 
     * @since 2.10
     */
    ACCEPT_CASE_INSENSITIVE_VALUES(false),

    /**
     * Feature that can be enabled to make property names be
     * overridden by wrapper name (usually detected with annotations
     * as defined by {@link AnnotationIntrospector#findWrapperName}.
     * If enabled, all properties that have associated non-empty Wrapper
     * name will use that wrapper name instead of property name.
     * If disabled, wrapper name is only used for wrapping (if anything).
     *<p>
     * Feature is disabled by default.
     * 
     * @since 2.1
     */
    USE_WRAPPER_NAME_AS_PROPERTY_NAME(false),

    /**
     * Feature that may be enabled to enforce strict compatibility with
     * Bean name introspection, instead of slightly different mechanism
     * Jackson defaults to.
     * Specific difference is that Jackson always lower cases leading upper-case
     * letters, so "getURL()" becomes "url" property; whereas standard Bean
     * naming <b>only</b> lower-cases the first letter if it is NOT followed by
     * another upper-case letter (so "getURL()" would result in "URL" property).
     *<p>
     * Feature is disabled by default for backwards compatibility purposes: earlier
     * Jackson versions used Jackson's own mechanism.
     *
     * @since 2.5
     */
    USE_STD_BEAN_NAMING(false),

    /**
     * Feature that when enabled will allow explicitly named properties (i.e., fields or methods
     * annotated with {@link com.fasterxml.jackson.annotation.JsonProperty}("explicitName")) to
     * be re-named by a {@link PropertyNamingStrategy}, if one is configured.
     * <p>
     * Feature is disabled by default.
     *
     * @since 2.7
     */
    ALLOW_EXPLICIT_PROPERTY_RENAMING(false),

    /*
    /******************************************************
    /* Coercion features
    /******************************************************
     */

    /**
     * Feature that determines whether coercions from secondary representations are allowed
     * for simple non-textual scalar types: numbers and booleans. This includes `primitive`
     * types and their wrappers, but excludes `java.lang.String` and date/time types.
     *<p>
     * When feature is disabled, only strictly compatible input may be bound: numbers for
     * numbers, boolean values for booleans. When feature is enabled, conversions from
     * JSON String are allowed, as long as textual value matches (for example, String
     * "true" is allowed as equivalent of JSON boolean token `true`; or String "1.0"
     * for `double`).
     *<p>
     * Note that it is possible that other configurability options can override this
     * in closer scope (like on per-type or per-property basis); this is just the global
     * default.
     *<p>
     * Feature is enabled by default (for backwards compatibility since this was the
     * default behavior)
     *
     * @since 2.9
     */
    ALLOW_COERCION_OF_SCALARS(true),

    /*
    /******************************************************
    /* Other features
    /******************************************************
     */

    /**
     * Feature that determines whether multiple registrations of same module
     * should be ignored or not; if enabled, only the first registration call
     * results in module being called, and possible duplicate calls are silently
     * ignored; if disabled, no checking is done and all registration calls are
     * dispatched to module.
     *<p>
     * Definition of "same module" is based on using {@link Module#getTypeId()};
     * modules with same non-null <code>type id</code> are considered same for
     * purposes of duplicate registration. This also avoids having to keep track
     * of actual module instances; only ids will be kept track of (and only if
     * this feature is enabled).
     *<p>
     * Feature is enabled by default.
     *
     * @since 2.5
     */
    IGNORE_DUPLICATE_MODULE_REGISTRATIONS(true),

    /**
     * Setting that determines what happens if an attempt is made to explicitly
     * "merge" value of a property, where value does not support merging; either
     * merging is skipped and new value is created (<code>true</code>) or
     * an exception is thrown (false).
     *<p>
     * Feature is enabled by default, to allow use of merge defaults even in presence
     * of some unmergeable properties.
     *
     * @since 2.9
     */
    IGNORE_MERGE_FOR_UNMERGEABLE(true),

    /**
     * Setting that may be enabled to reconfigure <b>default</b>
     * {@link com.fasterxml.jackson.databind.jsontype.PolymorphicTypeValidator}
     * used by legacy {@code ObjectMapper.enableDefaultTyping()} methods as well as default used
     * for annotation-based polymorphic handling so that it uses
     * {@link com.fasterxml.jackson.databind.jsontype.DefaultBaseTypeLimitingValidator}.
     * This will block use of a set of "unsafe" base types such as {@link java.lang.Object}
     * through methods that do not require passing of explicit {@link com.fasterxml.jackson.databind.jsontype.PolymorphicTypeValidator}.
     * It is still possible to override one used; this only affects default settings.
     *<p>
     * Enabling of this setting is <b>strongly recommended</b>.
     *<p>
     * Feature is disabled by default in 2.x for backwards compatibility reasons: it will become
     * default setting (and feature likely removed) in 3.0.
     * 
     * @since 2.11
     */
    BLOCK_UNSAFE_POLYMORPHIC_BASE_TYPES(false)
    ;

    private final boolean _defaultState;
    private final int _mask;
    
    private MapperFeature(boolean defaultState) {
        _defaultState = defaultState;
        _mask = (1 << ordinal());
    }
    
    @Override
    public boolean enabledByDefault() { return _defaultState; }

    @Override
    public int getMask() { return _mask; }

    @Override
    public boolean enabledIn(int flags) { return (flags & _mask) != 0; }
}

com/fasterxml/jackson/databind/MapperFeature.java

 

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