/*
* Copyright (C) 2004, 2005, 2006 Joe Walnes.
* Copyright (C) 2006, 2007, 2008 XStream Committers.
* All rights reserved.
*
* The software in this package is published under the terms of the BSD
* style license a copy of which has been included with this distribution in
* the LICENSE.txt file.
*
* Created on 21. December 2004 by Joe Walnes
*/
package com.thoughtworks.xstream.converters.reflection;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputValidation;
import java.io.ObjectStreamClass;
import java.io.ObjectStreamField;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.core.util.CustomObjectInputStream;
import com.thoughtworks.xstream.core.util.CustomObjectOutputStream;
import com.thoughtworks.xstream.core.util.HierarchicalStreams;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.io.ExtendedHierarchicalStreamWriterHelper;
import com.thoughtworks.xstream.mapper.Mapper;
/**
* Emulates the mechanism used by standard Java Serialization for classes that implement java.io.Serializable AND
* implement or inherit a custom readObject()/writeObject() method.
*
* <h3>Supported features of serialization</h3>
* <ul>
* <li>readObject(), writeObject()</li>
* <li>class inheritance</li>
* <li>readResolve(), writeReplace()</li>
* </ul>
*
* <h3>Currently unsupported features</h3>
* <ul>
* <li>putFields(), writeFields(), readFields()</li>
* <li>ObjectStreamField[] serialPersistentFields</li>
* <li>ObjectInputValidation</li>
* </ul>
*
* @author Joe Walnes
* @author Jörg Schaible
*/
public class SerializableConverter extends AbstractReflectionConverter {
private static final String ELEMENT_NULL = "null";
private static final String ELEMENT_DEFAULT = "default";
private static final String ELEMENT_UNSERIALIZABLE_PARENTS = "unserializable-parents";
private static final String ATTRIBUTE_CLASS = "class";
private static final String ATTRIBUTE_SERIALIZATION = "serialization";
private static final String ATTRIBUTE_VALUE_CUSTOM = "custom";
private static final String ELEMENT_FIELDS = "fields";
private static final String ELEMENT_FIELD = "field";
private static final String ATTRIBUTE_NAME = "name";
public SerializableConverter(Mapper mapper, ReflectionProvider reflectionProvider) {
super(mapper, new UnserializableParentsReflectionProvider(reflectionProvider));
}
public boolean canConvert(Class type) {
return isSerializable(type);
}
private boolean isSerializable(Class type) {
return Serializable.class.isAssignableFrom(type)
&& ( serializationMethodInvoker.supportsReadObject(type, true)
|| serializationMethodInvoker.supportsWriteObject(type, true) );
}
public void doMarshal(final Object source, final HierarchicalStreamWriter writer, final MarshallingContext context) {
String attributeName = mapper.aliasForSystemAttribute(ATTRIBUTE_SERIALIZATION);
if (attributeName != null) {
writer.addAttribute(attributeName, ATTRIBUTE_VALUE_CUSTOM);
}
// this is an array as it's a non final value that's accessed from an anonymous inner class.
final Class[] currentType = new Class[1];
final boolean[] writtenClassWrapper = {false};
CustomObjectOutputStream.StreamCallback callback = new CustomObjectOutputStream.StreamCallback() {
public void writeToStream(Object object) {
if (object == null) {
writer.startNode(ELEMENT_NULL);
writer.endNode();
} else {
ExtendedHierarchicalStreamWriterHelper.startNode(writer, mapper.serializedClass(object.getClass()), object.getClass());
context.convertAnother(object);
writer.endNode();
}
}
public void writeFieldsToStream(Map fields) {
ObjectStreamClass objectStreamClass = ObjectStreamClass.lookup(currentType[0]);
writer.startNode(ELEMENT_DEFAULT);
for (Iterator iterator = fields.keySet().iterator(); iterator.hasNext();) {
String name = (String) iterator.next();
if (!mapper.shouldSerializeMember(currentType[0], name)) {
continue;
}
ObjectStreamField field = objectStreamClass.getField(name);
Object value = fields.get(name);
if (field == null) {
throw new ObjectAccessException("Class " + value.getClass().getName()
+ " may not write a field named '" + name + "'");
}
if (value != null) {
ExtendedHierarchicalStreamWriterHelper.startNode(writer, mapper.serializedMember(source.getClass(), name), field.getType());
if (field.getType() != value.getClass() && !field.getType().isPrimitive()) {
String attributeName = mapper.aliasForSystemAttribute(ATTRIBUTE_CLASS);
if (attributeName != null) {
writer.addAttribute(attributeName, mapper.serializedClass(value.getClass()));
}
}
context.convertAnother(value);
writer.endNode();
}
}
writer.endNode();
}
public void defaultWriteObject() {
boolean writtenDefaultFields = false;
ObjectStreamClass objectStreamClass = ObjectStreamClass.lookup(currentType[0]);
if (objectStreamClass == null) {
return;
}
ObjectStreamField[] fields = objectStreamClass.getFields();
for (int i = 0; i < fields.length; i++) {
ObjectStreamField field = fields[i];
Object value = readField(field, currentType[0], source);
if (value != null) {
if (!writtenClassWrapper[0]) {
writer.startNode(mapper.serializedClass(currentType[0]));
writtenClassWrapper[0] = true;
}
if (!writtenDefaultFields) {
writer.startNode(ELEMENT_DEFAULT);
writtenDefaultFields = true;
}
if (!mapper.shouldSerializeMember(currentType[0], field.getName())) {
continue;
}
ExtendedHierarchicalStreamWriterHelper.startNode(writer, mapper.serializedMember(source.getClass(), field.getName()), field.getType());
Class actualType = value.getClass();
Class defaultType = mapper.defaultImplementationOf(field.getType());
if (!actualType.equals(defaultType)) {
String attributeName = mapper.aliasForSystemAttribute(ATTRIBUTE_CLASS);
if (attributeName != null) {
writer.addAttribute(attributeName, mapper.serializedClass(actualType));
}
}
context.convertAnother(value);
writer.endNode();
}
}
if (writtenClassWrapper[0] && !writtenDefaultFields) {
writer.startNode(ELEMENT_DEFAULT);
writer.endNode();
} else if (writtenDefaultFields) {
writer.endNode();
}
}
public void flush() {
writer.flush();
}
public void close() {
throw new UnsupportedOperationException("Objects are not allowed to call ObjectOutputStream.close() from writeObject()");
}
};
try {
boolean mustHandleUnserializableParent = false;
Iterator classHieararchy = hierarchyFor(source.getClass()).iterator();
while (classHieararchy.hasNext()) {
currentType[0] = (Class) classHieararchy.next();
if (!Serializable.class.isAssignableFrom(currentType[0])) {
mustHandleUnserializableParent = true;
continue;
} else {
if (mustHandleUnserializableParent) {
marshalUnserializableParent(writer, context, source);
mustHandleUnserializableParent = false;
}
if (serializationMethodInvoker.supportsWriteObject(currentType[0], false)) {
writtenClassWrapper[0] = true;
writer.startNode(mapper.serializedClass(currentType[0]));
CustomObjectOutputStream objectOutputStream = CustomObjectOutputStream.getInstance(context, callback);
serializationMethodInvoker.callWriteObject(currentType[0], source, objectOutputStream);
objectOutputStream.popCallback();
writer.endNode();
} else if (serializationMethodInvoker.supportsReadObject(currentType[0], false)) {
// Special case for objects that have readObject(), but not writeObject().
// The class wrapper is always written, whether or not this class in the hierarchy has
// serializable fields. This guarantees that readObject() will be called upon deserialization.
writtenClassWrapper[0] = true;
writer.startNode(mapper.serializedClass(currentType[0]));
callback.defaultWriteObject();
writer.endNode();
} else {
writtenClassWrapper[0] = false;
callback.defaultWriteObject();
if (writtenClassWrapper[0]) {
writer.endNode();
}
}
}
}
} catch (IOException e) {
throw new ObjectAccessException("Could not call defaultWriteObject()", e);
}
}
private void marshalUnserializableParent(final HierarchicalStreamWriter writer, final MarshallingContext context, final Object replacedSource) {
writer.startNode(ELEMENT_UNSERIALIZABLE_PARENTS);
super.doMarshal(replacedSource, writer, context);
writer.endNode();
}
private Object readField(ObjectStreamField field, Class type, Object instance) {
try {
Field javaField = type.getDeclaredField(field.getName());
javaField.setAccessible(true);
return javaField.get(instance);
} catch (IllegalArgumentException e) {
throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
} catch (IllegalAccessException e) {
throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
} catch (NoSuchFieldException e) {
throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
} catch (SecurityException e) {
throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
}
}
protected List hierarchyFor(Class type) {
List result = new ArrayList();
while(type != Object.class) {
result.add(type);
type = type.getSuperclass();
}
// In Java Object Serialization, the classes are deserialized starting from parent class and moving down.
Collections.reverse(result);
return result;
}
public Object doUnmarshal(final Object result, final HierarchicalStreamReader reader, final UnmarshallingContext context) {
// this is an array as it's a non final value that's accessed from an anonymous inner class.
final Class[] currentType = new Class[1];
String attributeName = mapper.aliasForSystemAttribute(ATTRIBUTE_SERIALIZATION);
if (attributeName != null && !ATTRIBUTE_VALUE_CUSTOM.equals(reader.getAttribute(attributeName))) {
throw new ConversionException("Cannot deserialize object with new readObject()/writeObject() methods");
}
CustomObjectInputStream.StreamCallback callback = new CustomObjectInputStream.StreamCallback() {
public Object readFromStream() {
reader.moveDown();
Class type = HierarchicalStreams.readClassType(reader, mapper);
Object value = context.convertAnother(result, type);
reader.moveUp();
return value;
}
public Map readFieldsFromStream() {
final Map fields = new HashMap();
reader.moveDown();
if (reader.getNodeName().equals(ELEMENT_FIELDS)) {
// Maintain compatibility with XStream 1.1.0
while (reader.hasMoreChildren()) {
reader.moveDown();
if (!reader.getNodeName().equals(ELEMENT_FIELD)) {
throw new ConversionException("Expected <" + ELEMENT_FIELD + "/> element inside <" + ELEMENT_FIELD + "/>");
}
String name = reader.getAttribute(ATTRIBUTE_NAME);
Class type = mapper.realClass(reader.getAttribute(ATTRIBUTE_CLASS));
Object value = context.convertAnother(result, type);
fields.put(name, value);
reader.moveUp();
}
} else if (reader.getNodeName().equals(ELEMENT_DEFAULT)) {
// New format introduced in XStream 1.1.1
ObjectStreamClass objectStreamClass = ObjectStreamClass.lookup(currentType[0]);
while (reader.hasMoreChildren()) {
reader.moveDown();
String name = mapper.realMember(currentType[0], reader.getNodeName());
if (mapper.shouldSerializeMember(currentType[0], name)) {
String classAttribute = HierarchicalStreams.readClassAttribute(reader, mapper);
Class type;
if (classAttribute != null) {
type = mapper.realClass(classAttribute);
} else {
ObjectStreamField field = objectStreamClass.getField(name);
if (field == null) {
throw new ObjectAccessException("Class " + currentType[0]
+ " does not contain a field named '" + name + "'");
}
type = field.getType();
}
Object value = context.convertAnother(result, type);
fields.put(name, value);
}
reader.moveUp();
}
} else {
throw new ConversionException("Expected <" + ELEMENT_FIELDS + "/> or <" +
ELEMENT_DEFAULT + "/> element when calling ObjectInputStream.readFields()");
}
reader.moveUp();
return fields;
}
public void defaultReadObject() {
if (!reader.hasMoreChildren()) {
return;
}
reader.moveDown();
if (!reader.getNodeName().equals(ELEMENT_DEFAULT)) {
throw new ConversionException("Expected <" + ELEMENT_DEFAULT + "/> element in readObject() stream");
}
while (reader.hasMoreChildren()) {
reader.moveDown();
String fieldName = mapper.realMember(currentType[0], reader.getNodeName());
if (mapper.shouldSerializeMember(currentType[0], fieldName)) {
String classAttribute = HierarchicalStreams.readClassAttribute(reader, mapper);
final Class type;
if (classAttribute != null) {
type = mapper.realClass(classAttribute);
} else {
type = mapper.defaultImplementationOf(reflectionProvider.getFieldType(result, fieldName, currentType[0]));
}
Object value = context.convertAnother(result, type);
reflectionProvider.writeField(result, fieldName, value, currentType[0]);
}
reader.moveUp();
}
reader.moveUp();
}
public void registerValidation(final ObjectInputValidation validation, int priority) {
context.addCompletionCallback(new Runnable() {
public void run() {
try {
validation.validateObject();
} catch (InvalidObjectException e) {
throw new ObjectAccessException("Cannot validate object : " + e.getMessage(), e);
}
}
}, priority);
}
public void close() {
throw new UnsupportedOperationException("Objects are not allowed to call ObjectInputStream.close() from readObject()");
}
};
while (reader.hasMoreChildren()) {
reader.moveDown();
String nodeName = reader.getNodeName();
if (nodeName.equals(ELEMENT_UNSERIALIZABLE_PARENTS)) {
super.doUnmarshal(result, reader, context);
} else {
String classAttribute = HierarchicalStreams.readClassAttribute(reader, mapper);
if (classAttribute == null) {
currentType[0] = mapper.defaultImplementationOf(mapper.realClass(nodeName));
} else {
currentType[0] = mapper.realClass(classAttribute);
}
if (serializationMethodInvoker.supportsReadObject(currentType[0], false)) {
CustomObjectInputStream objectInputStream = CustomObjectInputStream.getInstance(context, callback);
serializationMethodInvoker.callReadObject(currentType[0], result, objectInputStream);
objectInputStream.popCallback();
} else {
try {
callback.defaultReadObject();
} catch (IOException e) {
throw new ObjectAccessException("Could not call defaultWriteObject()", e);
}
}
}
reader.moveUp();
}
return result;
}
protected void doMarshalConditionally(final Object source, final HierarchicalStreamWriter writer, final MarshallingContext context) {
if(isSerializable(source.getClass())) {
doMarshal(source, writer, context);
} else {
super.doMarshal(source, writer, context);
}
}
protected Object doUnmarshalConditionally(final Object result, final HierarchicalStreamReader reader, final UnmarshallingContext context) {
return isSerializable(result.getClass()) ? doUnmarshal(result, reader, context) : super.doUnmarshal(result, reader, context);
}
private static class UnserializableParentsReflectionProvider extends ReflectionProviderWrapper {
public UnserializableParentsReflectionProvider(final ReflectionProvider reflectionProvider) {
super(reflectionProvider);
}
public void visitSerializableFields(final Object object, final Visitor visitor) {
wrapped.visitSerializableFields(object, new Visitor() {
public void visit(String name, Class type, Class definedIn, Object value) {
if (!Serializable.class.isAssignableFrom(definedIn)) {
visitor.visit(name, type, definedIn, value);
}
}
});
}
}
}