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java.lang.Objectorg.codehaus.jackson.map.JsonDeserializer<T>
public abstract class JsonDeserializer<T>
Abstract class that defines API used by ObjectMapper
(and
other chained JsonDeserializer
s too) to deserialize Objects of
arbitrary types from JSON, using provided JsonParser
.
Nested Class Summary | |
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static class |
JsonDeserializer.None
This marker class is only to be used with annotations, to indicate that no deserializer is configured. |
Constructor Summary | |
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JsonDeserializer()
|
Method Summary | |
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abstract T |
deserialize(JsonParser jp,
DeserializationContext ctxt)
Method that can be called to ask implementation to deserialize json content into the value type this serializer handles. |
T |
deserialize(JsonParser jp,
DeserializationContext ctxt,
T intoValue)
Alternate deserialization method (compared to the most commonly used, deserialize(JsonParser, DeserializationContext) ),
which takes in initialized value instance, to be
configured and/or populated by deserializer. |
Object |
deserializeWithType(JsonParser jp,
DeserializationContext ctxt,
TypeDeserializer typeDeserializer)
Deserialization called when type being deserialized is defined to contain additional type identifier, to allow for correctly instantiating correct subtype. |
T |
getNullValue()
Method that can be called to determine value to be used for representing null values (values deserialized when Json token is JsonToken.VALUE_NULL ). |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public JsonDeserializer()
Method Detail |
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public abstract T deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException
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.
jp
- Parsed used for reading Json contentctxt
- Context that can be used to access information about
this deserialization activity.
IOException
JsonProcessingException
public T deserialize(JsonParser jp, DeserializationContext ctxt, T intoValue) throws IOException, JsonProcessingException
deserialize(JsonParser, DeserializationContext)
),
which takes in initialized value instance, to be
configured and/or populated by deserializer.
Method is not necessarily used for all supported types; most commonly
it is used
for Collections and Maps.
Default implementation just throws
UnsupportedOperationException
, to indicate that types
that do not explicitly add support do not expect to get the call.
IOException
JsonProcessingException
public Object deserializeWithType(JsonParser jp, DeserializationContext ctxt, TypeDeserializer typeDeserializer) throws IOException, JsonProcessingException
Default implementation may work for some types, but ideally subclasses should not rely on current default implementation. Implementation is mostly provided to avoid compilation errors with older code.
typeDeserializer
- Deserializer to use for handling type information
IOException
JsonProcessingException
public T getNullValue()
JsonToken.VALUE_NULL
). Usually this is simply
Java null, but for some types (primitives) it may be
necessary to use actual 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.
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