Deserializers.java
package com.fasterxml.jackson.databind.deser;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.type.*;
/**
* Interface that defines API for simple extensions that can provide additional deserializers
* for various types. Access is by a single callback method; instance is to either return
* a configured {@link JsonDeserializer} for specified type, or null to indicate that it
* does not support handling of the type. In latter case, further calls can be made
* for other providers; in former case returned deserializer is used for handling of
* instances of specified type.
*<p>
* It is <b>strongly recommended</b> that implementations always extend {@link Deserializers.Base}
* and NOT just implement {@link Deserializers}.
*/
public interface Deserializers
{
// // // Scalar types first:
/**
* Method called to locate deserializer for specified {@link java.lang.Enum} type.
*
* @param type Type of {@link java.lang.Enum} instances to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findEnumDeserializer(Class<?> type,
DeserializationConfig config, BeanDescription beanDesc)
throws JsonMappingException;
/**
* Method called to locate deserializer for specified JSON tree node type.
*
* @param nodeType Specific type of JSON tree nodes to deserialize
* (subtype of {@link com.fasterxml.jackson.databind.JsonNode})
* @param config Configuration in effect
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findTreeNodeDeserializer(Class<? extends JsonNode> nodeType,
DeserializationConfig config, BeanDescription beanDesc)
throws JsonMappingException;
/**
* Method called to locate deserializer for specified value type which does not belong to any other
* category (not an Enum, Collection, Map, Array, reference value or tree node)
*
* @param type Bean type to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findBeanDeserializer(JavaType type,
DeserializationConfig config, BeanDescription beanDesc)
throws JsonMappingException;
// // // Then container types
/**
* Method called to locate deserializer for value that is of referential
* type,
*
* @param refType Specific referential type to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the reference type that contains class annotations and
* other information typically needed for building deserializers
* @param contentTypeDeserializer Possible type deserializer for referenced value
* @param contentDeserializer Value deserializer to use for referenced value, if indicated
* by property annotation
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*
* @since 2.7
*/
public JsonDeserializer<?> findReferenceDeserializer(ReferenceType refType,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer contentTypeDeserializer, JsonDeserializer<?> contentDeserializer)
throws JsonMappingException;
/**
* Method called to locate serializer for specified array type.
*<p>
* Deserializer for element type may be passed, if configured explicitly at higher level (by
* annotations, typically), but usually are not.
* Type deserializer for element is passed if one is needed based on contextual information
* (annotations on declared element class; or on field or method type is associated with).
*
* @param type Type of array instances to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
* @param elementTypeDeserializer If element type needs polymorphic type handling, this is
* the type information deserializer to use; should usually be used as is when constructing
* array deserializer.
* @param elementDeserializer Deserializer to use for elements, if explicitly defined (by using
* annotations, for exmple). May be null, in which case it should be resolved here (or using
* {@link ResolvableDeserializer} callback)
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findArrayDeserializer(ArrayType type,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException;
/**
* Method called to locate serializer for specified {@link java.util.Collection} (List, Set etc) type.
*<p>
* Deserializer for element type may be passed, if configured explicitly at higher level (by
* annotations, typically), but usually are not.
* Type deserializer for element is passed if one is needed based on contextual information
* (annotations on declared element class; or on field or method type is associated with).
*
* @param type Type of collection instances to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
* @param elementTypeDeserializer If element type needs polymorphic type handling, this is
* the type information deserializer to use; should usually be used as is when constructing
* array deserializer.
* @param elementDeserializer Deserializer to use for elements, if explicitly defined (by using
* annotations, for exmple). May be null, in which case it should be resolved here (or using
* {@link ResolvableDeserializer} callback)
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findCollectionDeserializer(CollectionType type,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException;
/**
* Method called to locate serializer for specified
* "Collection-like" type (one that acts
* like {@link java.util.Collection} but does not implement it).
*<p>
* Deserializer for element type may be passed, if configured explicitly at higher level (by
* annotations, typically), but usually are not.
* Type deserializer for element is passed if one is needed based on contextual information
* (annotations on declared element class; or on field or method type is associated with).
*
* @param type Type of instances to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
* @param elementTypeDeserializer If element type needs polymorphic type handling, this is
* the type information deserializer to use; should usually be used as is when constructing
* array deserializer.
* @param elementDeserializer Deserializer to use for elements, if explicitly defined (by using
* annotations, for exmple). May be null, in which case it should be resolved here (or using
* {@link ResolvableDeserializer} callback)
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findCollectionLikeDeserializer(CollectionLikeType type,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException;
/**
* Method called to locate deserializer for specified {@link java.util.Map} type.
*<p>
* Deserializer for element type may be passed, if configured explicitly at higher level (by
* annotations, typically), but usually are not.
* Type deserializer for element is passed if one is needed based on contextual information
* (annotations on declared element class; or on field or method type is associated with).
*<p>
* Similarly, a {@link KeyDeserializer} may be passed, but this is only done if there is
* a specific configuration override (annotations) to indicate instance to use.
* Otherwise null is passed, and key deserializer needs to be obtained later during
* resolution (using {@link ResolvableDeserializer#resolve}).
*
* @param type Type of {@link java.util.Map} instances to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
* @param keyDeserializer Key deserializer use, if it is defined via annotations or other configuration;
* null if default key deserializer for key type can be used.
* @param elementTypeDeserializer If element type needs polymorphic type handling, this is
* the type information deserializer to use; should usually be used as is when constructing
* array deserializer.
* @param elementDeserializer Deserializer to use for elements, if explicitly defined (by using
* annotations, for exmple). May be null, in which case it should be resolved here (or using
* {@link ResolvableDeserializer} callback)
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findMapDeserializer(MapType type,
DeserializationConfig config, BeanDescription beanDesc,
KeyDeserializer keyDeserializer,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException;
/**
* Method called to locate serializer for specified
* "Map-like" type (one that acts
* like {@link java.util.Map} but does not implement it).
*<p>
* Deserializer for element type may be passed, if configured explicitly at higher level (by
* annotations, typically), but usually are not.
* Type deserializer for element is passed if one is needed based on contextual information
* (annotations on declared element class; or on field or method type is associated with).
*<p>
* Similarly, a {@link KeyDeserializer} may be passed, but this is only done if there is
* a specific configuration override (annotations) to indicate instance to use.
* Otherwise null is passed, and key deserializer needs to be obtained later during
* resolution (using {@link ResolvableDeserializer#resolve}).
*
* @param type Type of {@link java.util.Map} instances to deserialize
* @param config Configuration in effect
* @param beanDesc Definition of the enumeration type that contains class annotations and
* other information typically needed for building deserializers
* @param keyDeserializer Key deserializer use, if it is defined via annotations or other configuration;
* null if default key deserializer for key type can be used.
* @param elementTypeDeserializer If element type needs polymorphic type handling, this is
* the type information deserializer to use; should usually be used as is when constructing
* array deserializer.
* @param elementDeserializer Deserializer to use for elements, if explicitly defined (by using
* annotations, for exmple). May be null, in which case it should be resolved here (or using
* {@link ResolvableDeserializer} callback)
*
* @return Deserializer to use for the type; or null if this provider does not know how to construct it
*/
public JsonDeserializer<?> findMapLikeDeserializer(MapLikeType type,
DeserializationConfig config, BeanDescription beanDesc,
KeyDeserializer keyDeserializer,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException;
/**
* Method that may be called to check whether this deserializer provider would provide
* deserializer for values of given type, without attempting to construct (and possibly
* fail in some cases) actual deserializer. Mostly needed to support validation
* of polymorphic type ids.
*<p>
* Note: implementations should take care NOT to claim supporting types that they do
* not recognize as this could to incorrect assumption of safe support by caller.
*<p>
* Method added in Jackson 2.13 now that Java 8 default implementations are available
* for use with interface definitions.
*
* @since 2.13
*/
public default boolean hasDeserializerFor(DeserializationConfig config,
Class<?> valueType) {
return false;
}
/*
/**********************************************************************
/* Helper classes
/**********************************************************************
*/
/**
* Basic {@link Deserializers} implementation that implements all methods but provides
* no deserializers. Its main purpose is to serve as a base class so that
* sub-classes only need to override methods they need, as most of the time some
* of methods are not needed (especially enumeration and array deserializers are
* very rarely overridden).
*/
public abstract static class Base
implements Deserializers
{
@Override
public JsonDeserializer<?> findEnumDeserializer(Class<?> type,
DeserializationConfig config, BeanDescription beanDesc)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findTreeNodeDeserializer(Class<? extends JsonNode> nodeType,
DeserializationConfig config, BeanDescription beanDesc)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findReferenceDeserializer(ReferenceType refType,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer contentTypeDeserializer, JsonDeserializer<?> contentDeserializer)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findBeanDeserializer(JavaType type,
DeserializationConfig config, BeanDescription beanDesc)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findArrayDeserializer(ArrayType type,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findCollectionDeserializer(CollectionType type,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findCollectionLikeDeserializer(CollectionLikeType type,
DeserializationConfig config, BeanDescription beanDesc,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findMapDeserializer(MapType type,
DeserializationConfig config, BeanDescription beanDesc,
KeyDeserializer keyDeserializer,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException
{
return null;
}
@Override
public JsonDeserializer<?> findMapLikeDeserializer(MapLikeType type,
DeserializationConfig config, BeanDescription beanDesc,
KeyDeserializer keyDeserializer,
TypeDeserializer elementTypeDeserializer, JsonDeserializer<?> elementDeserializer)
throws JsonMappingException
{
return null;
}
}
}