com.esotericsoftware.kryo.serializers

Class CompatibleFieldSerializer<T>

java.lang.Object

com.esotericsoftware.kryo.Serializer<T>

com.esotericsoftware.kryo.serializers.FieldSerializer<T>

com.esotericsoftware.kryo.serializers.CompatibleFieldSerializer<T>

All Implemented Interfaces:

Comparator<FieldSerializer.CachedField>

public class CompatibleFieldSerializer<T>
extends FieldSerializer<T>

Serializes objects using direct field assignment, with limited support for forward and backward compatibility. Fields can be added or removed without invalidating previously serialized bytes. Note that changing the type of a field is not supported.

Removing fields when references are enabled can cause compatibility issues. See here.

There is additional overhead compared to FieldSerializer. A header is output the first time an object of a given type is serialized. The header consists of an int for the number of fields, then a String for each field name. Also, to support skipping the bytes for a field that no longer exists, for each field value an int is written that is the length of the value in bytes.

Note that the field data is identified by name. The situation where a super class has a field with the same name as a subclass must be avoided.

Author:

Nathan Sweet

Nested Class Summary

Nested classes/interfaces inherited from class com.esotericsoftware.kryo.serializers.FieldSerializer

FieldSerializer.Bind, FieldSerializer.CachedField<X>, FieldSerializer.CachedFieldFactory, FieldSerializer.Optional

Field Summary

Fields inherited from class com.esotericsoftware.kryo.serializers.FieldSerializer

removedFields

Constructor Summary

Constructors

Constructor and Description
CompatibleFieldSerializer(Kryo kryo, Class type)

Method Summary

Methods

Modifier and Type	Method and Description
T	read(Kryo kryo, Input input, Class<T> type) Reads bytes and returns a new object of the specified concrete type.
void	write(Kryo kryo, Output output, T object) This method can be called for different fields having the same type.

Methods inherited from class com.esotericsoftware.kryo.serializers.FieldSerializer

compare, copy, create, createCopy, getCopyTransient, getField, getFields, getGenerics, getGenericsScope, getKryo, getType, getUseAsmEnabled, getUseMemRegions, initializeCachedFields, rebuildCachedFields, rebuildCachedFields, removeField, removeField, setCopyTransient, setFieldsAsAccessible, setFieldsCanBeNull, setFixedFieldTypes, setGenerics, setIgnoreSyntheticFields, setUseAsm

Methods inherited from class com.esotericsoftware.kryo.Serializer

getAcceptsNull, isImmutable, setAcceptsNull, setImmutable

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

CompatibleFieldSerializer

public CompatibleFieldSerializer(Kryo kryo,
                         Class type)

Method Detail

write

public void write(Kryo kryo,
         Output output,
         T object)

Description copied from class: FieldSerializer

This method can be called for different fields having the same type. Even though the raw type is the same, if the type is generic, it could happen that different concrete classes are used to instantiate it. Therefore, in case of different instantiation parameters, the fields analysis should be repeated. TODO: Cache serializer instances generated for a given set of generic parameters. Reuse it later instead of recomputing every time.

Overrides:

write in class FieldSerializer<T>

object - May be null if Serializer.getAcceptsNull() is true.

read

public T read(Kryo kryo,
     Input input,
     Class<T> type)

Description copied from class: Serializer

Reads bytes and returns a new object of the specified concrete type.

Before Kryo can be used to read child objects, Kryo.reference(Object) must be called with the parent object to ensure it can be referenced by the child objects. Any serializer that uses Kryo to read a child object may need to be reentrant.

This method should not be called directly, instead this serializer can be passed to Kryo read methods that accept a serialier.

Overrides:

read in class FieldSerializer<T>

Returns:

May be null if Serializer.getAcceptsNull() is true.