| /** |
| * Copyright (C) 2015 DataTorrent, Inc. |
| * |
| * 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. |
| */ |
| package com.datatorrent.common.util; |
| |
| import java.io.ObjectStreamException; |
| import java.io.Serializable; |
| import java.lang.reflect.Constructor; |
| import java.lang.reflect.Field; |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Modifier; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Helper base class to ensure that Java Serializer is able to work with the transient final |
| * fields in the class which extends this class. By definition the transient fields are not serialized. |
| * But when such a field is declared final in the class, there is no way to initialize it either. So |
| * this class provides boilerplate code to play with the very uncommon serialization API and provides a |
| * way to easily and correctly serialize and deserialize such objects. The only condition is that the |
| * class of such object should provide either a copy constructor or a default constructor. * |
| * |
| * @since 3.0.0 |
| */ |
| public class SerializableObject implements Serializable |
| { |
| /** |
| * Create an instance of this class by invoking the copy constructor. |
| * If the copy constructor does not exist, this method tries to get |
| * a new instance using default constructor and then initializing all |
| * the non final or non transient fields of the new instance with the |
| * corresponding values from the deserialized operator. Users can override |
| * this method to invoke non default constructor. They can override |
| * transferState to just copy over the non final or non transient values |
| * from various fields of the src object. |
| * |
| * @return an instance of the operator. |
| * @throws ObjectStreamException |
| */ |
| public Object readResolve() throws ObjectStreamException |
| { |
| try { |
| Constructor<? extends SerializableObject> constructor = this.getClass().getConstructor(this.getClass()); |
| try { |
| constructor.setAccessible(true); |
| } |
| catch (SecurityException ex) { |
| logger.warn("Accessing copy constructor {} failed.", constructor, ex); |
| } |
| try { |
| return constructor.newInstance(this); |
| } |
| catch (InstantiationException ex) { |
| throw new RuntimeException("Instantiation using copy constructor failed!", ex); |
| } |
| catch (IllegalAccessException ex) { |
| throw new RuntimeException("Instantiation using copy constructor failed!", ex); |
| } |
| catch (IllegalArgumentException ex) { |
| throw new RuntimeException("Instantiation using copy constructor failed!", ex); |
| } |
| catch (InvocationTargetException ex) { |
| throw new RuntimeException("Instantiation using copy constructor failed!", ex); |
| } |
| } |
| catch (NoSuchMethodException snme) { |
| logger.debug("No copy constructor detected for class {}, trying default constructor.", this.getClass().getSimpleName()); |
| try { |
| SerializableObject newInstance = this.getClass().newInstance(); |
| transferStateTo(newInstance); |
| return newInstance; |
| } |
| catch (IllegalAccessException ex) { |
| throw new RuntimeException("Deserialization using default constructor failed!", ex); |
| } |
| catch (InstantiationException ex) { |
| throw new RuntimeException("Deserialization using default constructor failed!", ex); |
| } |
| } |
| } |
| |
| /** |
| * Copy over non final and non transient values from src to dest object. |
| * |
| * @param dest The object to which values are copied. |
| */ |
| public void transferStateTo(Object dest) |
| { |
| for (Class<?> clazz = getClass(); !clazz.equals(Object.class); clazz = clazz.getSuperclass()) { |
| Field[] fields = clazz.getDeclaredFields(); |
| for (Field field: fields) { |
| final int modifiers = field.getModifiers(); |
| if (!(Modifier.isFinal(modifiers) && Modifier.isTransient(modifiers) || Modifier.isStatic(modifiers))) { |
| try { |
| field.setAccessible(true); |
| } |
| catch (SecurityException ex) { |
| logger.warn("Cannot set field {} accessible.", field, ex); |
| } |
| try { |
| field.set(dest, field.get(this)); |
| } |
| catch (IllegalArgumentException ex) { |
| throw new RuntimeException("Getter/Setter argument failed using reflection on " + field, ex); |
| } |
| catch (IllegalAccessException ex) { |
| throw new RuntimeException("Getter/Setter access failed using reflection on " + field, ex); |
| } |
| if (!field.getType().isPrimitive()) { |
| try { |
| field.set(this, null); |
| } |
| catch (IllegalArgumentException ex) { |
| logger.warn("Failed to set field {} to null; generally it's harmless, but with reference counted data structure this may be an issue.", field, ex); |
| } |
| catch (IllegalAccessException ex) { |
| logger.warn("Failed to set field {} to null; generally it's harmless, but with reference counted data structure this may be an issue.", field, ex); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| private static final long serialVersionUID = 201505211622L; |
| private static final Logger logger = LoggerFactory.getLogger(SerializableObject.class); |
| } |