com.cedarsoftware.util.io

Class Resolver

java.lang.Object

com.cedarsoftware.util.io.Resolver

Direct Known Subclasses:

MapResolver, ObjectResolver

public abstract class Resolver
extends Object

This class is used to convert a source of Java Maps that were created from the JsonParser. These are in 'raw' form with no 'pointers'. This code will reconstruct the 'shape' of the graph by connecting @ref's to @ids. The subclasses that override this class can build an object graph using Java classes or a Map-of-Map representation. In both cases, the @ref value will be replaced with the Object (or Map) that had the corresponding @id.

Author:

John DeRegnaucourt ([email protected])
Copyright (c) Cedar Software LLC

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.*

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	Resolver.Missingfields stores missing fields information to notify client after the complete deserialization resolution

Field Summary

Fields

Modifier and Type	Field and Description
protected Collection<Resolver.Missingfields>	missingFields

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Resolver(ReadOptions readOptions, ReferenceTracker references)

Method Summary

Modifier and Type	Method and Description
protected void	cleanup()
protected Object	coerceCertainTypes(String type)
protected <T> T	convertMapsToObjects(JsonObject root) Walk a JsonObject (Map of String keys to values) and return the Java object equivalent filled in as best as possible (everything except unresolved reference fields or unresolved array/collection elements).
protected static void	convertMapToKeysItems(JsonObject map) Convert an input JsonObject map (known to represent a Map.class or derivative) that has regular keys and values to have its keys placed into @keys, and its values placed into @items.
protected Object	createInstance(Class clazz, JsonObject jsonObj) This method creates a Java Object instance based on the passed in parameters.
protected Object	createInstanceUsingClass(Class clazz, JsonObject jsonObj) Create an instance using the Class (clazz) provided and the values in the jsonObj.
protected Object	createInstanceUsingType(JsonObject jsonObj) Create an instance of a Java class using the ".type" field on the jsonObj.
protected EnumSet<?>	extractEnumSet(Class c, JsonObject jsonObj)
protected JsonReader.JsonClassReader	getCustomReader(Class c)
protected JsonReader	getReader() Deprecated.
protected void	patchUnresolvedReferences() For all fields where the value was "@ref":"n" where 'n' was the id of an object that had not yet been encountered in the stream, make the final substitution.
protected abstract Object	readWithFactoryIfExists(Object o, Class compType, Deque<JsonObject> stack)
protected void	rehashMaps() Process Maps/Sets (fix up their internal indexing structure) This is required because Maps hash items using hashCode(), which will change between VMs.
protected abstract void	traverseArray(Deque<JsonObject> stack, JsonObject jsonObj)
protected abstract void	traverseCollection(Deque<JsonObject> stack, JsonObject jsonObj)
abstract void	traverseFields(Deque<JsonObject> stack, JsonObject jsonObj)
abstract void	traverseFields(Deque<JsonObject> stack, JsonObject jsonObj, Set<String> excludeFields)
protected void	traverseMap(Deque<JsonObject> stack, JsonObject jsonObj) Process java.util.Map and it's derivatives.

Methods inherited from class java.lang.Object

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

Field Detail

missingFields

protected final Collection<Resolver.Missingfields> missingFields

Constructor Detail

Resolver

protected Resolver(ReadOptions readOptions,
                   ReferenceTracker references)

Method Detail

getReader

@Deprecated
protected JsonReader getReader()

Deprecated.

convertMapsToObjects

protected <T> T convertMapsToObjects(JsonObject root)

Walk a JsonObject (Map of String keys to values) and return the Java object equivalent filled in as best as possible (everything except unresolved reference fields or unresolved array/collection elements).

Parameters:

root - JsonObject reference to a Map-of-Maps representation of the JSON input after it has been completely read.

Returns:

Properly constructed, typed, Java object graph built from a Map of Maps representation (JsonObject root).

readWithFactoryIfExists

protected abstract Object readWithFactoryIfExists(Object o,
                                                  Class compType,
                                                  Deque<JsonObject> stack)

traverseFields

public abstract void traverseFields(Deque<JsonObject> stack,
                                    JsonObject jsonObj)

traverseFields

public abstract void traverseFields(Deque<JsonObject> stack,
                                    JsonObject jsonObj,
                                    Set<String> excludeFields)

traverseCollection

protected abstract void traverseCollection(Deque<JsonObject> stack,
                                           JsonObject jsonObj)

traverseArray

protected abstract void traverseArray(Deque<JsonObject> stack,
                                      JsonObject jsonObj)

cleanup

protected void cleanup()

traverseMap

protected void traverseMap(Deque<JsonObject> stack,
                           JsonObject jsonObj)

Process java.util.Map and it's derivatives. These are written specially so that the serialization does not expose the class internals (internal fields of TreeMap for example).

Parameters:

stack - a Stack (Deque) used to support graph traversal.

jsonObj - a Map-of-Map representation of the JSON input stream.

convertMapToKeysItems

protected static void convertMapToKeysItems(JsonObject map)

Convert an input JsonObject map (known to represent a Map.class or derivative) that has regular keys and values to have its keys placed into @keys, and its values placed into @items.

Parameters:

map - Map to convert

createInstance

protected Object createInstance(Class clazz,
                                JsonObject jsonObj)

This method creates a Java Object instance based on the passed in parameters. If the JsonObject contains a key '@type' then that is used, as the type was explicitly set in the JSON stream. If the key '@type' does not exist, then the passed in Class is used to create the instance, handling creating an Array or regular Object instance.
The '@type' is not often specified in the JSON input stream, as in many cases it can be inferred from a field reference or array component type.

Parameters:

clazz - Instance will be create of this class.

jsonObj - Map-of-Map representation of object to create.

Returns:

a new Java object of the appropriate type (clazz) using the jsonObj to provide enough hints to get the right class instantiated. It is not populated when returned.

createInstanceUsingType

protected Object createInstanceUsingType(JsonObject jsonObj)

Create an instance of a Java class using the ".type" field on the jsonObj. The clazz argument is not used for determining type, just for clarity in an exception message.

createInstanceUsingClass

protected Object createInstanceUsingClass(Class clazz,
                                          JsonObject jsonObj)

Create an instance using the Class (clazz) provided and the values in the jsonObj.

coerceCertainTypes

protected Object coerceCertainTypes(String type)

getCustomReader

protected JsonReader.JsonClassReader getCustomReader(Class c)

extractEnumSet

protected EnumSet<?> extractEnumSet(Class c,
                                    JsonObject jsonObj)

patchUnresolvedReferences

protected void patchUnresolvedReferences()

For all fields where the value was "@ref":"n" where 'n' was the id of an object that had not yet been encountered in the stream, make the final substitution.

rehashMaps

protected void rehashMaps()

Process Maps/Sets (fix up their internal indexing structure) This is required because Maps hash items using hashCode(), which will change between VMs. Rehashing the map fixes this.
If useMaps==true, then move @keys to keys and @items to values and then drop these two entries from the map.
This hashes both Sets and Maps because the JDK sets are implemented as Maps. If you have a custom built Set, this would not 'treat' it and you would need to provide a custom reader for that set.