com.fasterxml.jackson.databind.deser.std

Class StringDeserializer

java.lang.Object

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

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

com.fasterxml.jackson.databind.deser.std.StdScalarDeserializer<java.lang.String>

com.fasterxml.jackson.databind.deser.std.StringDeserializer

All Implemented Interfaces:

NullValueProvider, java.io.Serializable

public class StringDeserializer
extends StdScalarDeserializer<java.lang.String>

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 and Description
static StringDeserializer	instance

Constructor Summary

Constructors

Constructor and Description
StringDeserializer()

Method Summary

Modifier and Type	Method and Description
java.lang.String	deserialize(JsonParser p, DeserializationContext ctxt) Method that can be called to ask implementation to deserialize JSON content into the value type this serializer handles.
java.lang.String	deserializeWithType(JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer) Base implementation that does not assume specific type inclusion mechanism.
java.lang.Object	getEmptyValue(DeserializationContext ctxt) Method called to determine value to be used for "empty" values (most commonly when deserializing from empty JSON Strings).
boolean	isCachable() Method called to see if deserializer instance is cachable and usable for other properties of same type (type for which instance was created).

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, getKnownPropertyNames, getNullValue, getNullValue, getObjectIdReader, replaceDelegatee, unwrappingDeserializer

Methods inherited from class java.lang.Object

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

Field Detail

instance

public static final StringDeserializer instance

Since:

2.2

Constructor Detail

StringDeserializer

public StringDeserializer()

Method Detail

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.String>

getEmptyValue

public java.lang.Object getEmptyValue(DeserializationContext ctxt)
                               throws JsonMappingException

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(com.fasterxml.jackson.databind.DeserializationContext) (which in turn is usually simply Java null), but it can be overridden for specific types. Or, if type should never be converted from empty String, method can also throw an exception.

This method may be called once, or multiple times, depending on what JsonDeserializer.getEmptyAccessPattern() returns.

Default implementation simply calls JsonDeserializer.getNullValue(com.fasterxml.jackson.databind.DeserializationContext) and returns value.

Overrides:

getEmptyValue in class JsonDeserializer<java.lang.String>

Throws:

JsonMappingException

deserialize

public java.lang.String 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.String>

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

deserializeWithType

public java.lang.String 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 StdScalarDeserializer<java.lang.String>

typeDeserializer - Deserializer to use for handling type information

Throws:

java.io.IOException