/*
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* Copyright (C) 2011 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package cn.emay.sdk.util.json.gson.internal;
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import java.io.ObjectInputStream;
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import java.io.ObjectStreamClass;
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import java.lang.reflect.Field;
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import java.lang.reflect.Method;
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/**
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* Do sneaky things to allocate objects without invoking their constructors.
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*
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* @author Joel Leitch
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* @author Jesse Wilson
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*/
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public abstract class UnsafeAllocator {
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public abstract <T> T newInstance(Class<T> c) throws Exception;
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public static UnsafeAllocator create() {
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// try JVM
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// public class Unsafe {
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// public Object allocateInstance(Class<?> type);
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// }
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try {
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Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
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Field f = unsafeClass.getDeclaredField("theUnsafe");
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f.setAccessible(true);
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final Object unsafe = f.get(null);
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final Method allocateInstance = unsafeClass.getMethod("allocateInstance", Class.class);
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return new UnsafeAllocator() {
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@Override
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@SuppressWarnings("unchecked")
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public <T> T newInstance(Class<T> c) throws Exception {
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return (T) allocateInstance.invoke(unsafe, c);
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}
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};
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} catch (Exception ignored) {
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}
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// try dalvikvm, post-gingerbread
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// public class ObjectStreamClass {
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// private static native int getConstructorId(Class<?> c);
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// private static native Object newInstance(Class<?> instantiationClass, int
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// methodId);
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// }
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try {
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Method getConstructorId = ObjectStreamClass.class.getDeclaredMethod("getConstructorId", Class.class);
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getConstructorId.setAccessible(true);
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final int constructorId = (Integer) getConstructorId.invoke(null, Object.class);
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final Method newInstance = ObjectStreamClass.class.getDeclaredMethod("newInstance", Class.class, int.class);
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newInstance.setAccessible(true);
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return new UnsafeAllocator() {
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@Override
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@SuppressWarnings("unchecked")
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public <T> T newInstance(Class<T> c) throws Exception {
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return (T) newInstance.invoke(null, c, constructorId);
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}
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};
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} catch (Exception ignored) {
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}
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// try dalvikvm, pre-gingerbread
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// public class ObjectInputStream {
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// private static native Object newInstance(
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// Class<?> instantiationClass, Class<?> constructorClass);
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// }
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try {
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final Method newInstance = ObjectInputStream.class.getDeclaredMethod("newInstance", Class.class, Class.class);
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newInstance.setAccessible(true);
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return new UnsafeAllocator() {
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@Override
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@SuppressWarnings("unchecked")
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public <T> T newInstance(Class<T> c) throws Exception {
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return (T) newInstance.invoke(null, c, Object.class);
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}
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};
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} catch (Exception ignored) {
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}
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// give up
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return new UnsafeAllocator() {
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@Override
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public <T> T newInstance(Class<T> c) {
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throw new UnsupportedOperationException("Cannot allocate " + c);
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}
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};
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}
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}
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