com.fasterxml.jackson.databind.deser.std

Class DelegatingDeserializer

    • Constructor Detail

      • DelegatingDeserializer

        public DelegatingDeserializer(JsonDeserializer<?> delegatee)
    • Method Detail

      • resolve

        public void resolve(DeserializationContext ctxt)
                     throws JsonMappingException
        Description copied from interface: ResolvableDeserializer
        Method called after deserializer instance has been constructed (and registered as necessary by provider objects), but before it has returned it to the caller. Called object can then resolve its dependencies to other types, including self-references (direct or indirect).
        Specified by:
        resolve in interface ResolvableDeserializer
        Parameters:
        ctxt - Context to use for accessing configuration, resolving secondary deserializers
        Throws:
        JsonMappingException
      • createContextual

        public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
                                           BeanProperty property)
                                             throws JsonMappingException
        Description copied from interface: ContextualDeserializer
        Method called to see if a different (or differently configured) deserializer is needed to deserialize values of specified property. Note that instance that this method is called on is typically shared one and as a result method should NOT modify this instance but rather construct and return a new instance. This instance should only be returned as-is, in case it is already suitable for use.
        Specified by:
        createContextual in interface ContextualDeserializer
        Parameters:
        ctxt - Deserialization context to access configuration, additional deserializers that may be needed by this deserializer
        property - Method, field or constructor parameter that represents the property (and is used to assign deserialized value). Should be available; but there may be cases where caller can not provide it and null is passed instead (in which case impls usually pass 'this' deserializer as is)
        Returns:
        Deserializer to use for deserializing values of specified property; may be this instance or a new instance.
        Throws:
        JsonMappingException
      • deserialize

        public Object deserialize(JsonParser jp,
                         DeserializationContext ctxt)
                           throws IOException,
                                  JsonProcessingException
        Description copied from class: JsonDeserializer
        Method that can be called to ask implementation to deserialize JSON content into the value type this serializer handles. Returned instance is to be constructed by method itself.

        Pre-condition for this method is that the parser points to the first event that is part of value to deserializer (and which is never JSON 'null' literal, more on this below): for simple types it may be the only value; and for structured types the Object start marker. Post-condition is that the parser will point to the last event that is part of deserialized value (or in case deserialization fails, event that was not recognized or usable, which may be the same event as the one it pointed to upon call).

        Note that this method is never called for JSON null literal, and thus deserializers need (and should) not check for it.

        Specified by:
        deserialize in class JsonDeserializer<Object>
        Parameters:
        jp - Parsed used for reading JSON content
        ctxt - Context that can be used to access information about this deserialization activity.
        Returns:
        Deserialized value
        Throws:
        IOException
        JsonProcessingException
      • getNullValue

        public Object getNullValue()
        Description copied from class: JsonDeserializer
        Method that can be called to determine value to be used for representing null values (values deserialized when JSON token is JsonToken.VALUE_NULL). Usually this is simply Java null, but for some types (especially primitives) it may be necessary to use non-null values.

        Note that deserializers are allowed to call this just once and then reuse returned value; that is, method is not guaranteed to be called once for each conversion.

        Default implementation simply returns null.

        Overrides:
        getNullValue in class JsonDeserializer<Object>
      • getEmptyValue

        public Object getEmptyValue()
        Description copied from class: JsonDeserializer
        Method called to determine value to be used for "empty" values (most commonly when deserializing from empty JSON Strings). Usually this is same as JsonDeserializer.getNullValue() (which in turn is usually simply Java null), but it can be overridden for types. Or, if type should never be converted from empty String, method can also throw an exception.

        Default implementation simple calls JsonDeserializer.getNullValue() and returns value.

        Overrides:
        getEmptyValue in class JsonDeserializer<Object>
      • getKnownPropertyNames

        public Collection<Object> getKnownPropertyNames()
        Description copied from class: JsonDeserializer
        Method that will either return null to indicate that type being deserializers has no concept of properties; or a collection of identifiers for which toString will give external property name. This is only to be used for error reporting and diagnostics purposes (most commonly, to accompany "unknown property" exception).
        Overrides:
        getKnownPropertyNames in class JsonDeserializer<Object>
      • isCachable

        public boolean isCachable()
        Description copied from class: JsonDeserializer
        Method called to see if deserializer instance is cachable and usable for other properties of same type (type for which instance was created).

        Note that cached instances are still resolved on per-property basis, if instance implements ResolvableDeserializer: cached instance is just as the base. This means that in most cases it is safe to cache instances; however, it only makes sense to cache instances if instantiation is expensive, or if instances are heavy-weight.

        Default implementation returns false, to indicate that no caching is done.

        Overrides:
        isCachable in class JsonDeserializer<Object>
      • getObjectIdReader

        public ObjectIdReader getObjectIdReader()
        Description copied from class: JsonDeserializer
        Accessor that can be used to check whether this deserializer is expecting to possibly get an Object Identifier value instead of full value serialization, and if so, should be able to resolve it to actual Object instance to return as deserialized value.

        Default implementation returns null, as support can not be implemented generically. Some standard deserializers (most notably BeanDeserializer) do implement this feature, and may return reader instance, depending on exact configuration of instance (which is based on type, and referring property).

        Overrides:
        getObjectIdReader in class JsonDeserializer<Object>
        Returns:
        ObjectIdReader used for resolving possible Object Identifier value, instead of full value serialization, if deserializer can do that; null if no Object Id is expected.
      • getDelegatee

        public JsonDeserializer<?> getDelegatee()
        Description copied from class: JsonDeserializer
        Accessor that can be used to determine if this deserializer uses another deserializer for actual deserialization, by delegating calls. If so, will return immediate delegate (which itself may delegate to further deserializers); otherwise will return null.
        Overrides:
        getDelegatee in class JsonDeserializer<Object>
        Returns:
        Deserializer this deserializer delegates calls to, if null; null otherwise.

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