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

Class NumberDeserializers.NumberDeserializer

java.lang.Object

com.fasterxml.jackson.databind.JsonDeserializer<T>

com.fasterxml.jackson.databind.deser.std.StdDeserializer<T>

com.fasterxml.jackson.databind.deser.std.StdScalarDeserializer<Object>

com.fasterxml.jackson.databind.deser.std.NumberDeserializers.NumberDeserializer

All Implemented Interfaces:

NullValueProvider, Serializable

Enclosing class:

NumberDeserializers

public static class NumberDeserializers.NumberDeserializer
extends StdScalarDeserializer<Object>

For type Number.class, we can just rely on type mappings that plain JsonParser.getNumberValue() returns.

There is one additional complication: some numeric types (specifically, int/Integer and double/Double) are "non-typed"; meaning that they will NEVER be output with type information. But other numeric types may need such type information. This is why deserializeWithType(com.fasterxml.jackson.core.JsonParser, com.fasterxml.jackson.databind.DeserializationContext, com.fasterxml.jackson.databind.jsontype.TypeDeserializer) must be overridden.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.fasterxml.jackson.databind.JsonDeserializer

JsonDeserializer.None

Field Summary

Fields

Modifier and Type	Field	Description
static NumberDeserializers.NumberDeserializer	instance

Constructor Summary

Constructors

Constructor	Description
NumberDeserializer()

Method Summary

Modifier and Type	Method	Description
Object	deserialize(JsonParser p, DeserializationContext ctxt)	Method that can be called to ask implementation to deserialize JSON content into the value type this serializer handles.
Object	deserializeWithType(JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer)	As mentioned in class Javadoc, there is additional complexity in handling potentially mixed type information here.

Methods inherited from class com.fasterxml.jackson.databind.deser.std.StdScalarDeserializer

deserialize, getEmptyAccessPattern, getNullAccessPattern, supportsUpdate

Methods inherited from class com.fasterxml.jackson.databind.deser.std.StdDeserializer

getValueClass, getValueType, getValueType, handledType

Methods inherited from class com.fasterxml.jackson.databind.JsonDeserializer

deserializeWithType, findBackReference, getDelegatee, getEmptyValue, getEmptyValue, getKnownPropertyNames, getNullValue, getNullValue, getObjectIdReader, isCachable, replaceDelegatee, unwrappingDeserializer

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

instance

public static final NumberDeserializers.NumberDeserializer instance

Constructor Detail

NumberDeserializer

public NumberDeserializer()

Method Detail

deserialize

public Object deserialize(JsonParser p,
                          DeserializationContext ctxt)
                   throws 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<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:

IOException

deserializeWithType

public Object deserializeWithType(JsonParser p,
                                  DeserializationContext ctxt,
                                  TypeDeserializer typeDeserializer)
                           throws IOException

As mentioned in class Javadoc, there is additional complexity in handling potentially mixed type information here. Because of this, we must actually check for "raw" integers and doubles first, before calling type deserializer.

Overrides:

deserializeWithType in class StdScalarDeserializer<Object>

typeDeserializer - Deserializer to use for handling type information

Throws:

IOException