/*
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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.lang.reflect.Constructor;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.EnumSet;
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import java.util.LinkedHashMap;
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import java.util.LinkedHashSet;
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import java.util.LinkedList;
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import java.util.Map;
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import java.util.Queue;
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import java.util.Set;
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import java.util.SortedMap;
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import java.util.SortedSet;
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import java.util.TreeMap;
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import java.util.TreeSet;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.ConcurrentMap;
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import java.util.concurrent.ConcurrentNavigableMap;
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import java.util.concurrent.ConcurrentSkipListMap;
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import cn.emay.sdk.util.json.gson.InstanceCreator;
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import cn.emay.sdk.util.json.gson.JsonIOException;
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import cn.emay.sdk.util.json.gson.reflect.TypeToken;
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/**
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* Returns a function that can construct an instance of a requested type.
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*/
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public final class ConstructorConstructor {
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private final Map<Type, InstanceCreator<?>> instanceCreators;
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public ConstructorConstructor(Map<Type, InstanceCreator<?>> instanceCreators) {
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this.instanceCreators = instanceCreators;
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}
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public <T> ObjectConstructor<T> get(TypeToken<T> typeToken) {
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final Type type = typeToken.getType();
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final Class<? super T> rawType = typeToken.getRawType();
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// first try an instance creator
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@SuppressWarnings("unchecked") // types must agree
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final InstanceCreator<T> typeCreator = (InstanceCreator<T>) instanceCreators.get(type);
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if (typeCreator != null) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return typeCreator.createInstance(type);
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}
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};
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}
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// Next try raw type match for instance creators
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@SuppressWarnings("unchecked") // types must agree
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final InstanceCreator<T> rawTypeCreator = (InstanceCreator<T>) instanceCreators.get(rawType);
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if (rawTypeCreator != null) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return rawTypeCreator.createInstance(type);
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}
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};
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}
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ObjectConstructor<T> defaultConstructor = newDefaultConstructor(rawType);
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if (defaultConstructor != null) {
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return defaultConstructor;
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}
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ObjectConstructor<T> defaultImplementation = newDefaultImplementationConstructor(type, rawType);
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if (defaultImplementation != null) {
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return defaultImplementation;
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}
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// finally try unsafe
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return newUnsafeAllocator(type, rawType);
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}
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private <T> ObjectConstructor<T> newDefaultConstructor(Class<? super T> rawType) {
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try {
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final Constructor<? super T> constructor = rawType.getDeclaredConstructor();
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if (!constructor.isAccessible()) {
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constructor.setAccessible(true);
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}
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return new ObjectConstructor<T>() {
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@SuppressWarnings("unchecked") // T is the same raw type as is requested
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@Override
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public T construct() {
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try {
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Object[] args = null;
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return (T) constructor.newInstance(args);
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} catch (InstantiationException e) {
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// TODO: JsonParseException ?
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throw new RuntimeException("Failed to invoke " + constructor + " with no args", e);
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} catch (InvocationTargetException e) {
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// TODO: don't wrap if cause is unchecked!
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// TODO: JsonParseException ?
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throw new RuntimeException("Failed to invoke " + constructor + " with no args", e.getTargetException());
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} catch (IllegalAccessException e) {
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throw new AssertionError(e);
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}
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}
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};
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} catch (NoSuchMethodException e) {
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return null;
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}
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}
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/**
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* Constructors for common interface types like Map and List and their subtypes.
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*/
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@SuppressWarnings("unchecked") // use runtime checks to guarantee that 'T' is what it is
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private <T> ObjectConstructor<T> newDefaultImplementationConstructor(final Type type, Class<? super T> rawType) {
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if (Collection.class.isAssignableFrom(rawType)) {
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if (SortedSet.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new TreeSet<Object>();
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}
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};
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} else if (EnumSet.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@SuppressWarnings("rawtypes")
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@Override
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public T construct() {
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if (type instanceof ParameterizedType) {
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Type elementType = ((ParameterizedType) type).getActualTypeArguments()[0];
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if (elementType instanceof Class) {
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return (T) EnumSet.noneOf((Class) elementType);
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} else {
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throw new JsonIOException("Invalid EnumSet type: " + type.toString());
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}
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} else {
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throw new JsonIOException("Invalid EnumSet type: " + type.toString());
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}
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}
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};
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} else if (Set.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new LinkedHashSet<Object>();
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}
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};
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} else if (Queue.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new LinkedList<Object>();
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}
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};
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} else {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new ArrayList<Object>();
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}
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};
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}
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}
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if (Map.class.isAssignableFrom(rawType)) {
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if (ConcurrentNavigableMap.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new ConcurrentSkipListMap<Object, Object>();
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}
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};
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} else if (ConcurrentMap.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new ConcurrentHashMap<Object, Object>();
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}
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};
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} else if (SortedMap.class.isAssignableFrom(rawType)) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new TreeMap<Object, Object>();
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}
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};
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} else if (type instanceof ParameterizedType && !(String.class.isAssignableFrom(TypeToken.get(((ParameterizedType) type).getActualTypeArguments()[0]).getRawType()))) {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new LinkedHashMap<Object, Object>();
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}
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};
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} else {
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return new ObjectConstructor<T>() {
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@Override
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public T construct() {
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return (T) new LinkedTreeMap<String, Object>();
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}
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};
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}
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}
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return null;
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}
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private <T> ObjectConstructor<T> newUnsafeAllocator(final Type type, final Class<? super T> rawType) {
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return new ObjectConstructor<T>() {
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private final UnsafeAllocator unsafeAllocator = UnsafeAllocator.create();
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@SuppressWarnings("unchecked")
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@Override
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public T construct() {
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try {
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Object newInstance = unsafeAllocator.newInstance(rawType);
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return (T) newInstance;
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} catch (Exception e) {
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throw new RuntimeException(("Unable to invoke no-args constructor for " + type + ". " + "Register an InstanceCreator with Gson for this type may fix this problem."), e);
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}
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}
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};
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}
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@Override
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public String toString() {
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return instanceCreators.toString();
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}
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}
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