Package com.fasterxml.jackson.databind.deser.std

Class DelegatingDeserializer

    • Constructor Detail

      • DelegatingDeserializer

        public DelegatingDeserializer​(JsonDeserializer<?> d)

    • 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 cannot 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

      • replaceDelegatee

        public JsonDeserializer<?> replaceDelegatee​(JsonDeserializer<?> delegatee)
        Description copied from class: JsonDeserializer
        Method that can be called to try to replace deserializer this deserializer delegates calls to. If not supported (either this deserializer does not delegate anything; or it does not want any changes), should either throw UnsupportedOperationException (if operation does not make sense or is not allowed); or return this deserializer as is.
        Overrides:
        replaceDelegatee in class JsonDeserializer<java.lang.Object>

      • deserialize

        public java.lang.Object deserialize​(JsonParser p,
                                    DeserializationContext ctxt)
                             throws java.io.IOException
        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 or a FIELD_NAME.

        The two possible input conditions for structured types result from polymorphism via fields. In the ordinary case, Jackson calls this method when it has encountered an OBJECT_START, and the method implementation must advance to the next token to see the first field name. If the application configures polymorphism via a field, then the object looks like the following. 

              {
          "@class": "class name",
          ...
      }
        Jackson consumes the two tokens (the @class field name and its value) in order to learn the class and select the deserializer. Thus, the stream is pointing to the FIELD_NAME for the first field after the @class. Thus, if you want your method to work correctly both with and without polymorphism, you must begin your method with: 
               if (p.currentToken() == JsonToken.START_OBJECT) {
         p.nextToken();
       }
        This results in the stream pointing to the field name, so that the two conditions align.

        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<java.lang.Object>
        Parameters:
        p - Parsed used for reading JSON content
        ctxt - Context that can be used to access information about this deserialization activity.
        Returns:
        Deserialized value
        Throws:
        java.io.IOException

      • deserialize

        public java.lang.Object deserialize​(JsonParser p,
                                    DeserializationContext ctxt,
                                    java.lang.Object intoValue)
                             throws java.io.IOException
        Description copied from class: JsonDeserializer
        Alternate deserialization method (compared to the most commonly used, JsonDeserializer.deserialize(JsonParser, DeserializationContext)), which takes in initialized value instance, to be configured and/or populated by deserializer. Method is not necessarily used (or supported) by all types (it will not work for immutable types, for obvious reasons): most commonly it is used for Collections and Maps. It may be used both with "updating readers" (for POJOs) and when Collections and Maps use "getter as setter".

        Default implementation just throws UnsupportedOperationException, to indicate that types that do not explicitly add support do not necessarily support update-existing-value operation (esp. immutable types)

        Overrides:
        deserialize in class JsonDeserializer<java.lang.Object>
        Throws:
        java.io.IOException

      • deserializeWithType

        public java.lang.Object deserializeWithType​(JsonParser p,
                                            DeserializationContext ctxt,
                                            TypeDeserializer typeDeserializer)
                                     throws java.io.IOException
        Description copied from class: StdDeserializer
        Base implementation that does not assume specific type inclusion mechanism. Sub-classes are expected to override this method if they are to handle type information.
        Overrides:
        deserializeWithType in class StdDeserializer<java.lang.Object>
        typeDeserializer - Deserializer to use for handling type information
        Throws:
        java.io.IOException

      • 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<java.lang.Object>

      • supportsUpdate

        public java.lang.Boolean supportsUpdate​(DeserializationConfig config)
        Description copied from class: JsonDeserializer
        Introspection method that may be called to see whether deserializer supports update of an existing value (aka "merging") or not. Return value should either be Boolean.FALSE if update is not supported at all (immutable values); Boolean.TRUE if update should usually work (regular POJOs, for example), or null if this is either not known, or may sometimes work.

        Information gathered is typically used to either prevent merging update for property (either by skipping, if based on global defaults; or by exception during deserialization construction if explicit attempt made) if Boolean.FALSE returned, or inclusion if Boolean.TRUE is specified. If "unknown" case (null returned) behavior is to exclude property if global defaults used; or to allow if explicit per-type or property merging is defined.

        Default implementation returns null to allow explicit per-type or per-property attempts.

        Overrides:
        supportsUpdate in class JsonDeserializer<java.lang.Object>

      • 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<java.lang.Object>
        Returns:
        Deserializer this deserializer delegates calls to, if null; null otherwise.

      • logicalType

        public LogicalType logicalType()
        Description copied from class: JsonDeserializer
        Method for accessing logical type of values this deserializer produces. Typically used for further configuring handling of values, for example, to find which coercions are legal.
        Overrides:
        logicalType in class JsonDeserializer<java.lang.Object>
        Returns:
        Logical type of values this deserializer produces, if known; null if not

      • getKnownPropertyNames

        public java.util.Collection<java.lang.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<java.lang.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 cannot 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<java.lang.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.