com.brettonw.bedrock.bag.Serializer Maven / Gradle / Ivy
package com.brettonw.bedrock.bag;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import sun.reflect.ReflectionFactory;
import java.lang.reflect.*;
import java.util.*;
public class Serializer {
private static final Logger log = LogManager.getLogger (Serializer.class);
// the static interface
private static final String SPECIAL_CHAR = "@";
static final String TYPE_KEY = SPECIAL_CHAR + "type";
static final String VERSION_KEY = SPECIAL_CHAR + "v";
static final String KEY_KEY = SPECIAL_CHAR + "key";
static final String VALUE_KEY = SPECIAL_CHAR + "value";
// future changes might require the serializer to know a different type of encoding is expected.
// we use a two step version, where changes in the ".x" region don't require a new deserializer
// but for which we want old version of serialization to fail. changes in the "1." region
// indicate a completely new deserializer is needed. we will not ever support serializing to
// older formats (link against the old version of this package if you want that). we will decide
// whether or not to support multiple deserializer formats when the time comes.
static final String SERIALIZER_VERSION_1 = "1.0";
static final String SERIALIZER_VERSION_2 = "2";
static final String SERIALIZER_VERSION_3 = "3";
static final String SERIALIZER_VERSION_4 = "4";
static final String SERIALIZER_VERSION = SERIALIZER_VERSION_4;
// flags to clarify whether or not to include/expect version
private static final boolean WITH_VERSION = true;
private static final boolean WITHOUT_VERSION = false;
// maps and sets to help with determining boxed type relationships
private static final Map BOXED_TYPES_MAP;
private static final Set BOXED_TYPES_SET;
static {
BOXED_TYPES_MAP = new HashMap<> ();
BOXED_TYPES_MAP.put ("int", Integer.class);
BOXED_TYPES_MAP.put ("long", Long.class);
BOXED_TYPES_MAP.put ("short", Short.class);
BOXED_TYPES_MAP.put ("byte", Byte.class);
BOXED_TYPES_MAP.put ("char", Character.class);
BOXED_TYPES_MAP.put ("boolean", Boolean.class);
BOXED_TYPES_MAP.put ("float", Float.class);
BOXED_TYPES_MAP.put ("double", Double.class);
BOXED_TYPES_SET = new HashSet<> ();
for (String key : BOXED_TYPES_MAP.keySet ()) {
BOXED_TYPES_SET.add (BOXED_TYPES_MAP.get (key));
}
}
/*
private static final class ClassLoaderResolver extends SecurityManager
{
private static final ClassLoaderResolver CLASS_LOADER_RESOLVER = new ClassLoaderResolver ();
static ClassLoader[] getCallStack () {
Class[] classCallStack = CLASS_LOADER_RESOLVER.getClassContext ();
ClassLoader[] classLoaderCallStack = new ClassLoader[classCallStack.length];
for (int i = 0, end = classCallStack.length; i < end; ++i) {
classLoaderCallStack[i] = classCallStack[i].getClassLoader ();
}
return classLoaderCallStack;
}
}
*/
private static Class getClass (String typeString) throws ClassNotFoundException {
/*
ClassLoader threadContextClassLoader = Thread.currentThread ().getContextClassLoader ();
ClassLoader systemClassLoader = ClassLoader.getSystemClassLoader ();
ClassLoader myClassLoader = Serializer.class.getClassLoader ();
ClassLoader[] classLoaderCallStack = ClassLoaderResolver.getCallStack ();
*/
return Serializer.class.getClassLoader ().loadClass (typeString);
}
// different types of objects are handled differently by the serializer, this is roughly how we
// group those types
enum SerializationType {
PRIMITIVE,
ENUM,
BAG_OBJECT,
BAG_ARRAY,
JAVA_OBJECT,
COLLECTION,
MAP,
ARRAY
}
private static boolean isBoxedPrimitive (Class type) {
// boxed primitives and strings...
return BOXED_TYPES_SET.contains (type) || (type.equals (String.class));
}
private static Class getBoxedType (String typeString) throws ClassNotFoundException {
return BOXED_TYPES_MAP.containsKey (typeString)
? BOXED_TYPES_MAP.get (typeString)
: getClass (typeString);
}
private static Class getBoxedType (Class type) {
Class boxedType = BOXED_TYPES_MAP.get (type.getName ());
return (boxedType != null) ? boxedType : type;
}
private static SerializationType serializationType (Class type) {
if (type.isPrimitive () || isBoxedPrimitive (type)) return SerializationType.PRIMITIVE;
if (type.isEnum ()) return SerializationType.ENUM;
if (type.isArray ()) return SerializationType.ARRAY;
if (Collection.class.isAssignableFrom (type)) return SerializationType.COLLECTION;
if (Map.class.isAssignableFrom (type)) return SerializationType.MAP;
if (BagObject.class.isAssignableFrom (type)) return SerializationType.BAG_OBJECT;
if (BagArray.class.isAssignableFrom (type)) return SerializationType.BAG_ARRAY;
// if it's none of the above...
return SerializationType.JAVA_OBJECT;
}
private static SerializationType serializationType (String typeString) throws ClassNotFoundException {
return (typeString.charAt (0) == '[')
? SerializationType.ARRAY
: serializationType (getBoxedType (typeString));
}
private static Set getAllFields (Set fields, Class type) {
// recursively walk up the class declaration to gather all of the fields, but stop when we
// hit the top of the class hierarchy
if (type != null) {
fields.addAll (Arrays.asList (type.getFields ()));
fields.addAll (Arrays.asList (type.getDeclaredFields ()));
getAllFields (fields, type.getSuperclass ());
}
return fields;
}
private static BagObject serializeJavaObjectType (Object object, Class type) {
// this bedrock object will hold the value(s) of the fields
BagObject bagObject = new BagObject ();
// gather all of the fields declared; public, private, static, etc., then loop over them
Set fieldSet = getAllFields (new HashSet<> (), type);
for (Field field : fieldSet) {
// check if the field is static, we don't want to serialize any static values, as this
// leads to recursion
if (! Modifier.isStatic (field.getModifiers ())) {
// force accessibility for serialization - this is an issue with the reflection API
// that we want to step around because serialization is assumed to be the primary
// goal, as opposed to viewing a way to workaround an API that needs to be over-
// ridden. This should prevent the IllegalAccessException from ever happening.
boolean accessible = field.isAccessible ();
field.setAccessible (true);
// get the name and type, and get the value to encode
try {
// only serialize this field if it has a value
Object fieldObject = field.get (object);
if (fieldObject != null) {
// if the type of the object is not a subclass of the field type, serialize it
// directly - otherwise, serialize with type
Class fieldObjectType = getBoxedType (fieldObject.getClass ());
Class fieldType = getBoxedType (field.getType ());
if (fieldObjectType.isAssignableFrom (fieldType)) {
bagObject.put (field.getName (), serialize (fieldObject));
} else {
bagObject.put (field.getName (), serializeWithType (fieldObject, WITHOUT_VERSION));
}
}
} catch (IllegalAccessException exception) {
// NOTE this shouldn't happen, per the comments above, and is untestable for
// purpose of measuring coverage
log.debug (exception);
}
// restore the accessibility - not 100% sure this is necessary, better be safe than
// sorry, right?
field.setAccessible (accessible);
}
}
return bagObject;
}
private static BagArray serializeArrayType (Object object) {
int length = Array.getLength (object);
BagArray bagArray = new BagArray (length);
for (int i = 0; i < length; ++i) {
// serialized containers could use base classes as the container type specifier, so we
// have to instantiate each object individually
bagArray.add (serializeWithType (Array.get (object, i), WITHOUT_VERSION));
}
return bagArray;
}
private static BagArray serializeMapType (Map object) {
Object[] keys = object.keySet ().toArray ();
BagArray bagArray = new BagArray (keys.length);
for (Object key : keys) {
Object item = object.get (key);
// serialized containers could use base classes as the container type specifier, so we
// have to instantiate each object individually
BagObject pair = new BagObject (2)
.put (KEY_KEY, serializeWithType (key, WITHOUT_VERSION))
.put (VALUE_KEY, serializeWithType (item, WITHOUT_VERSION));
bagArray.add (pair);
}
return bagArray;
}
static Object serialize (Object object) {
// fill out the header of the encapsulating bedrock
Class type = object.getClass ();
// the next step depends on the actual type of what's being serialized
switch (serializationType (type)) {
case PRIMITIVE: return object;
case ENUM: return object.toString ();
case BAG_OBJECT: case BAG_ARRAY: return object;
case JAVA_OBJECT: return serializeJavaObjectType (object, type);
case COLLECTION: return serializeArrayType (((Collection) object).toArray ());
case MAP: return serializeMapType ((Map) object);
case ARRAY: return serializeArrayType (object);
}
return null;
}
private static BagObject serializeWithType (Object object, boolean emitVersion) {
if (object != null) {
// build an encapsulation for the serializer
return (emitVersion ? new BagObject (3).put (VERSION_KEY, SERIALIZER_VERSION) : new BagObject (2))
.put (TYPE_KEY, object.getClass ().getName ())
.put (VALUE_KEY, serialize (object));
}
return null;
}
/**
* Return the @value component of a serialized object
*
* @param bagObject the BagObject representing the serialized object.
* @return A BagObject from the @value component, or null if it's not a valid serialization.
*/
public static BagObject Unwrap (BagObject bagObject) {
return bagObject.getBagObject (VALUE_KEY);
}
/**
* Convert the given object to a BagObject representation that can be used to reconstitute the
* given object after serialization.
*
* @param object the target element to serialize. It must be one of the following: primitive,
* boxed-primitive, Plain Old Java Object (POJO) class, object class with getters
* and setters for all members, BagObject, BagArray, array, or list or map-based
* container of one of the previously mentioned types.
* @return A BagObject encapsulation of the target object, or null if the conversion failed.
*/
public static BagObject toBagObject (Object object) {
return serializeWithType (object, WITH_VERSION);
}
private static Object deserializePrimitiveType (String typeString, Object object) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InstantiationException, InvocationTargetException {
String string = (String) object;
Class type = getBoxedType (typeString);
// Character types don't have a constructor from a String, so we have to handle that as a
// special case. Fingers crossed we don't find any others
return (type.isAssignableFrom (Character.class))
? type.getConstructor (char.class).newInstance (string.charAt (0))
: type.getConstructor (String.class).newInstance (string);
}
private static Object deserializeJavaEnumType (String typeString, Object object) throws ClassNotFoundException {
Class type = getClass (typeString);
return Enum.valueOf (type, (String) object);
}
private static Object deserializeJavaObjectType (String typeString, Object object) throws ClassNotFoundException, IllegalAccessException, NoSuchMethodException, InstantiationException, InvocationTargetException {
Object target;
// get the local classloader, and try to get the requested type from it
// "In this dirty old part of the city, Where the sun refused to shine..."
Class type = getClass (typeString);
Constructor constructor = null;
// try to get a default constructor
try {
constructor = type.getConstructor ();
log.debug ("Instantiate " + type.getName () + " using default constructor...");
} catch (NoSuchMethodException exception) {
// skip this, user the serialization interface
}
// try to get a constructor using the serialization interface, this should effectively
// create the object without any initialization at all.
if (constructor == null) {
ReflectionFactory reflectionFactory = ReflectionFactory.getReflectionFactory ();
Constructor objectConstructor = Object.class.getDeclaredConstructor ();
constructor = reflectionFactory.newConstructorForSerialization (type, objectConstructor);
log.debug ("Instantiate " + type.getName () + " using serialization constructor...");
}
// instantiate the object
target = constructor.newInstance ();
// Wendy, is the water warm enough? Yes, Lisa. (Prince, RIP)
if (target != null) {
// gather all of the fields declared; public, private, static, etc., then loop over them
BagObject bagObject = (BagObject) object;
Set fieldSet = getAllFields (new HashSet<> (), type);
for (Field field : fieldSet) {
// only populate this field if we serialized it
if (bagObject.has (field.getName ())) {
// force accessibility for serialization, as above... this should prevent the
// IllegalAccessException from ever happening.
boolean accessible = field.isAccessible ();
field.setAccessible (true);
// get the name and type, and set the value from the encode value
//log.trace ("Add " + field.getName () + " as " + field.getType ().getName ());
Object fieldObject = bagObject.getObject (field.getName ());
String fieldType = field.getType ().getName ();
if ((fieldObject instanceof BagObject) && (((BagObject) fieldObject).getString (TYPE_KEY) != null)) {
field.set (target, deserializeWithType ((BagObject) fieldObject, WITHOUT_VERSION));
} else {
field.set (target, deserialize (fieldType, fieldObject));
}
// restore the accessibility - not 100% sure this is necessary, better be safe
// than sorry, right?
field.setAccessible (accessible);
} else {
// warn about skipping a non-static field
if (! Modifier.isStatic (field.getModifiers ())) {
log.warn ("Skipping non-static field initializer (" + field.getName () + "), not in source bedrock object");
}
}
}
}
return target;
}
private static Object deserializeCollectionType (String typeString, Object object) throws ClassNotFoundException, IllegalAccessException, InstantiationException {
Class type = getClass (typeString);
Collection target = (Collection) type.newInstance ();
BagArray bagArray = (BagArray) object;
for (int i = 0, end = bagArray.getCount (); i < end; ++i) {
target.add (deserializeWithType (bagArray.getBagObject (i), WITHOUT_VERSION));
}
return target;
}
private static Object deserializeMapType (String typeString, Object object) throws ClassNotFoundException, IllegalAccessException, InstantiationException {
Class type = getClass (typeString);
Map target = (Map) type.newInstance ();
BagArray bagArray = (BagArray) object;
for (int i = 0, end = bagArray.getCount (); i < end; ++i) {
BagObject entry = bagArray.getBagObject (i);
Object key = deserializeWithType (entry.getBagObject (KEY_KEY), WITHOUT_VERSION);
Object value = deserializeWithType (entry.getBagObject (VALUE_KEY), WITHOUT_VERSION);
target.put (key, value);
}
return target;
}
private static Class getArrayType (String typeName) throws ClassNotFoundException {
int arrayDepth = 0;
while (typeName.charAt (arrayDepth) == '[') { ++arrayDepth; }
switch (typeName.substring (arrayDepth)) {
case "B": return byte.class;
case "C": return char.class;
case "D": return double.class;
case "F": return float.class;
case "I": return int.class;
case "J": return long.class;
case "S": return short.class;
case "Z": return boolean.class;
case "Ljava.lang.Byte;": return Byte.class;
case "Ljava.lang.Character;": return Character.class;
case "Ljava.lang.Double;": return Double.class;
case "Ljava.lang.Float;": return Float.class;
case "Ljava.lang.Integer;": return Integer.class;
case "Ljava.lang.Long;": return Long.class;
case "Ljava.lang.Short;": return Short.class;
case "Ljava.lang.Boolean;": return Boolean.class;
}
// if we get here, the type is either a class name, or ???
if (typeName.charAt (arrayDepth) == 'L') {
int semiColon = typeName.indexOf (';');
typeName = typeName.substring (arrayDepth + 1, semiColon);
// note that this could throw ClassNotFound if the typeName is not legitimate.
return getClass (typeName);
}
// this will only happen if we are deserializing from modified source
throw new ClassNotFoundException(typeName);
}
private static int[] getArraySizes (String typeString, BagArray bagArray) {
// figure the array dimension
int dimension = 0;
while (typeString.charAt (dimension) == '[') { ++dimension; }
// create and populate the sizes array
int sizes[] = new int[dimension];
for (int i = 0; i < dimension; ++i) {
sizes[i] = bagArray.getCount ();
bagArray = bagArray.getBagObject (0).getBagArray (VALUE_KEY);
}
// return the result
return sizes;
}
private static void populateArray(int x, int[] arraySizes, Object target, BagArray bagArray) {
if (x < (arraySizes.length - 1)) {
// we should recur for each value to populate a sub-array
for (int i = 0, end = arraySizes[x]; i < end; ++i) {
Object nextTarget = Array.get (target, i);
BagObject bagObject = bagArray.getBagObject (i);
populateArray (x + 1, arraySizes, nextTarget, bagObject.getBagArray (VALUE_KEY));
}
} else {
// we should set each value
for (int i = 0, end = arraySizes[x]; i < end; ++i) {
Array.set (target, i, deserializeWithType (bagArray.getBagObject (i), WITHOUT_VERSION));
}
}
}
private static Object deserializeArrayType (String typeString, Object object) throws ClassNotFoundException {
BagArray bagArray = (BagArray) object;
int[] arraySizes = getArraySizes (typeString, bagArray);
Class type = getArrayType (typeString);
Object target = Array.newInstance (type, arraySizes);
populateArray (0, arraySizes, target, bagArray);
return target;
}
private static boolean checkVersion (boolean expectVersion, BagObject bagObject) throws BadVersionException {
if (expectVersion) {
String version = bagObject.getString (VERSION_KEY);
if (!SERIALIZER_VERSION.equals (version)) {
throw new BadVersionException (version, SERIALIZER_VERSION);
}
}
return true;
}
static Object deserialize (String typeString, Object object) {
Object result = null;
try {
switch (serializationType (typeString)) {
case PRIMITIVE: result = deserializePrimitiveType (typeString, object); break;
case ENUM: result = deserializeJavaEnumType (typeString, object); break;
case BAG_OBJECT:
case BAG_ARRAY: result = object; break;
case JAVA_OBJECT: result = deserializeJavaObjectType (typeString, object); break;
case COLLECTION: result = deserializeCollectionType (typeString, object); break;
case MAP: result = deserializeMapType (typeString, object); break;
case ARRAY: result = deserializeArrayType (typeString, object); break;
}
} catch (Exception exception) {
log.error (exception);
}
return result;
}
private static Object deserializeWithType (BagObject bagObject, boolean expectVersion) {
return ((bagObject != null) && checkVersion (expectVersion, bagObject))
? deserialize (bagObject.getString (TYPE_KEY), bagObject.getObject (VALUE_KEY))
: null;
}
/**
* Reconstitute the given BagObject representation back to the object it represents.
*
* @param template parameter for the type to return
* @param bagObject the target BagObject to deserialize. It must be a valid representation of
* the encoded type(i.e. created by the toBagObject method).
* @return the reconstituted object, or null if the reconstitution failed.
*/
public static WorkingType fromBagObject (BagObject bagObject) {
// we expect a future change might use a different approach to deserialization, so we
// check to be sure this is the version we are working to
return (WorkingType) deserializeWithType (bagObject, WITH_VERSION);
}
/**
* Reconstitute the given BagObject representation back to the object it represents, using a
* "best-effort" approach to matching the fields of the BagObject to the class being initialized.
* @param bag The input data to reconstruct from, either a BagObject or BagArray
* @param type the Class representing the type to reconstruct
* @return the reconstituted object, or null if the reconstitution failed.
*/
public static WorkingType fromBagAsType (Bag bag, Class type) {
return (bag != null) ? (WorkingType) deserialize (type.getName (), bag) : null;
}
}
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