org.codehaus.jackson.map.deser
Class ValueInstantiator

java.lang.Object
  extended by org.codehaus.jackson.map.deser.ValueInstantiator
Direct Known Subclasses:
StdValueInstantiator

public abstract class ValueInstantiator
extends Object

Class that defines simple API implemented by objects that create value instances. Some or all of properties of value instances may be initialized by instantiator, rest being populated by deserializer, to which value instance is passed. Since different kinds of JSON values (structured and scalar) may be bound to Java values, in some cases instantiator fully defines resulting value; this is the case when JSON value is a scalar value (String, number, boolean).

Note that this type is not parameterized (even though it would seemingly make sense), because such type information can not be use effectively during runtime: access is always using either wildcard type, or just basic Object; and so adding type parameter seems like unnecessary extra work.

Actual implementations are strongly recommended to be based on StdValueInstantiator which implements all methods, and as such will be compatible across versions even if new methods were added to this interface.

Since:
1.9

Constructor Summary
ValueInstantiator()
           
 
Method Summary
 boolean canCreateFromBoolean()
          Method that can be called to check whether a double (boolean / Boolean) based creator is available to use (to call createFromDouble(double)).
 boolean canCreateFromDouble()
          Method that can be called to check whether a double (double / Double) based creator is available to use (to call createFromDouble(double)).
 boolean canCreateFromInt()
          Method that can be called to check whether an integer (int, Integer) based creator is available to use (to call createFromInt(int)).
 boolean canCreateFromLong()
          Method that can be called to check whether a long (long, Long) based creator is available to use (to call createFromLong(long)).
 boolean canCreateFromObjectWith()
          Method that can be called to check whether a property-based creator (argument-taking constructor or factory method) is available to instantiate values from JSON Object
 boolean canCreateFromString()
          Method that can be called to check whether a String-based creator is available for this instantiator
 boolean canCreateUsingDefault()
          Method that can be called to check whether a default creator (constructor, or no-arg static factory method) is available for this instantiator
 boolean canCreateUsingDelegate()
          Method that can be called to check whether a delegate-based creator (single-arg constructor or factory method) is available for this instantiator
 boolean canInstantiate()
          Method that will return true if any of canCreateXxx method returns true: that is, if there is any way that an instance could be created.
 Object createFromBoolean(boolean value)
           
 Object createFromDouble(double value)
           
 Object createFromInt(int value)
           
 Object createFromLong(long value)
           
 Object createFromObjectWith(Object[] args)
          Method called to create value instance from JSON Object when instantiation arguments are passed; this is done, for example when passing information specified with "Creator" annotations.
 Object createFromString(String value)
           
 Object createUsingDefault()
          Method called to create value instance from a JSON value when no data needs to passed to creator (constructor, factory method); typically this will call the default constructor of the value object.
 Object createUsingDelegate(Object delegate)
          Method to called to create value instance from JSON Object using an intermediate "delegate" value to pass to createor method
 AnnotatedWithParams getDefaultCreator()
          Method that can be called to try to access member (constructor, static factory method) that is used as the "default creator" (creator that is called without arguments; typically default [zero-argument] constructor of the type).
 AnnotatedWithParams getDelegateCreator()
          Method that can be called to try to access member (constructor, static factory method) that is used as the "delegate creator".
 JavaType getDelegateType()
          Method that can be used to determine what is the type of delegate type to use, if any; if no delegates are used, will return null.
 SettableBeanProperty[] getFromObjectArguments()
          Method called to determine types of instantiation arguments to use when creating instances with creator arguments (when canCreateFromObjectWith() returns true).
abstract  String getValueTypeDesc()
          Method that returns description of the value type this instantiator handles.
 AnnotatedWithParams getWithArgsCreator()
          Method that can be called to try to access member (constructor, static factory method) that is used as the "non-default creator" (constructor or factory method that takes one or more arguments).
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ValueInstantiator

public ValueInstantiator()
Method Detail

getValueTypeDesc

public abstract String getValueTypeDesc()
Method that returns description of the value type this instantiator handles. Used for error messages, diagnostics.


canInstantiate

public boolean canInstantiate()
Method that will return true if any of canCreateXxx method returns true: that is, if there is any way that an instance could be created.


canCreateFromString

public boolean canCreateFromString()
Method that can be called to check whether a String-based creator is available for this instantiator


canCreateFromInt

public boolean canCreateFromInt()
Method that can be called to check whether an integer (int, Integer) based creator is available to use (to call createFromInt(int)).


canCreateFromLong

public boolean canCreateFromLong()
Method that can be called to check whether a long (long, Long) based creator is available to use (to call createFromLong(long)).


canCreateFromDouble

public boolean canCreateFromDouble()
Method that can be called to check whether a double (double / Double) based creator is available to use (to call createFromDouble(double)).


canCreateFromBoolean

public boolean canCreateFromBoolean()
Method that can be called to check whether a double (boolean / Boolean) based creator is available to use (to call createFromDouble(double)).


canCreateUsingDefault

public boolean canCreateUsingDefault()
Method that can be called to check whether a default creator (constructor, or no-arg static factory method) is available for this instantiator


canCreateUsingDelegate

public boolean canCreateUsingDelegate()
Method that can be called to check whether a delegate-based creator (single-arg constructor or factory method) is available for this instantiator


canCreateFromObjectWith

public boolean canCreateFromObjectWith()
Method that can be called to check whether a property-based creator (argument-taking constructor or factory method) is available to instantiate values from JSON Object


getFromObjectArguments

public SettableBeanProperty[] getFromObjectArguments()
Method called to determine types of instantiation arguments to use when creating instances with creator arguments (when canCreateFromObjectWith() returns true). These arguments are bound from JSON, using specified property types to locate deserializers.

NOTE: all properties will be of type CreatorProperty.


getDelegateType

public JavaType getDelegateType()
Method that can be used to determine what is the type of delegate type to use, if any; if no delegates are used, will return null. If non-null type is returned, deserializer will bind JSON into specified type (using standard deserializer for that type), and pass that to instantiator.


createUsingDefault

public Object createUsingDefault()
                          throws IOException,
                                 JsonProcessingException
Method called to create value instance from a JSON value when no data needs to passed to creator (constructor, factory method); typically this will call the default constructor of the value object. It will only be used if more specific creator methods are not applicable; hence "default".

This method is called if getFromObjectArguments() returns null or empty List.

Throws:
IOException
JsonProcessingException

createFromObjectWith

public Object createFromObjectWith(Object[] args)
                            throws IOException,
                                   JsonProcessingException
Method called to create value instance from JSON Object when instantiation arguments are passed; this is done, for example when passing information specified with "Creator" annotations.

This method is called if getFromObjectArguments() returns a non-empty List of arguments.

Throws:
IOException
JsonProcessingException

createUsingDelegate

public Object createUsingDelegate(Object delegate)
                           throws IOException,
                                  JsonProcessingException
Method to called to create value instance from JSON Object using an intermediate "delegate" value to pass to createor method

Throws:
IOException
JsonProcessingException

createFromString

public Object createFromString(String value)
                        throws IOException,
                               JsonProcessingException
Throws:
IOException
JsonProcessingException

createFromInt

public Object createFromInt(int value)
                     throws IOException,
                            JsonProcessingException
Throws:
IOException
JsonProcessingException

createFromLong

public Object createFromLong(long value)
                      throws IOException,
                             JsonProcessingException
Throws:
IOException
JsonProcessingException

createFromDouble

public Object createFromDouble(double value)
                        throws IOException,
                               JsonProcessingException
Throws:
IOException
JsonProcessingException

createFromBoolean

public Object createFromBoolean(boolean value)
                         throws IOException,
                                JsonProcessingException
Throws:
IOException
JsonProcessingException

getDefaultCreator

public AnnotatedWithParams getDefaultCreator()
Method that can be called to try to access member (constructor, static factory method) that is used as the "default creator" (creator that is called without arguments; typically default [zero-argument] constructor of the type). Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if canCreateUsingDefault() returns true, this method may return null .


getDelegateCreator

public AnnotatedWithParams getDelegateCreator()
Method that can be called to try to access member (constructor, static factory method) that is used as the "delegate creator". Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if canCreateUsingDelegate() returns true, this method may return null .


getWithArgsCreator

public AnnotatedWithParams getWithArgsCreator()
Method that can be called to try to access member (constructor, static factory method) that is used as the "non-default creator" (constructor or factory method that takes one or more arguments). Note that implementations not required to return actual object they use (or, they may use some other instantiation) method. That is, even if canCreateFromObjectWith() returns true, this method may return null .