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Issue 971: adding TypeAdapterFactory and adjusting configuration to allow use of Inject, Named and ConstructorProperties annotations
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.../org/jclouds/json/internal/DeserializationConstructorAndReflectiveTypeAdapterFactory.java
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| /** | ||
| * Licensed to jclouds, Inc. (jclouds) under one or more | ||
| * contributor license agreements. See the NOTICE file | ||
| * distributed with this work for additional information | ||
| * regarding copyright ownership. jclouds licenses this file | ||
| * to you 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 org.jclouds.json.internal; | ||
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| import static com.google.common.base.Preconditions.checkArgument; | ||
| import static com.google.common.base.Preconditions.checkNotNull; | ||
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| import java.io.IOException; | ||
| import java.lang.reflect.Constructor; | ||
| import java.lang.reflect.InvocationTargetException; | ||
| import java.lang.reflect.Type; | ||
| import java.util.LinkedHashMap; | ||
| import java.util.Map; | ||
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| import org.jclouds.json.internal.NamingStrategies.ConstructorFieldNamingStrategy; | ||
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| import com.google.gson.FieldNamingStrategy; | ||
| import com.google.gson.Gson; | ||
| import com.google.gson.JsonSyntaxException; | ||
| import com.google.gson.TypeAdapter; | ||
| import com.google.gson.TypeAdapterFactory; | ||
| import com.google.gson.internal.$Gson$Types; | ||
| import com.google.gson.internal.ConstructorConstructor; | ||
| import com.google.gson.internal.Excluder; | ||
| import com.google.gson.internal.bind.ReflectiveTypeAdapterFactory; | ||
| import com.google.gson.reflect.TypeToken; | ||
| import com.google.gson.stream.JsonReader; | ||
| import com.google.gson.stream.JsonToken; | ||
| import com.google.gson.stream.JsonWriter; | ||
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| /** | ||
| * Creates type adapters for types handled in the following ways: | ||
| * <p/> | ||
| * <ul> | ||
| * <li>Deserialization</li> | ||
| * If there's an annotation designating a parameterized constructor, invoke that for fields | ||
| * correlating to named parameter annotations. Otherwise, use {@link ConstructorConstructor}, and | ||
| * set fields via reflection. | ||
| * <li>Serialization</li> | ||
| * Serialize based on reflective access to fields, delegating to ReflectiveTypeAdaptor. | ||
| * </ul> | ||
| * <h3>Example: Using javax inject to select a constructor and corresponding named parameters</h3> | ||
| * <p/> | ||
| * <pre> | ||
| * | ||
| * import NamingStrategies.*; | ||
| * | ||
| * serializationStrategy = new AnnotationOrNameFieldNamingStrategy( | ||
| * new ExtractSerializedName(), new ExtractNamed()); | ||
| * | ||
| * deserializationStrategy = new AnnotationConstructorNamingStrategy( | ||
| * Collections.singleton(javax.inject.Inject.class), | ||
| * Collections.singleton(new ExtractNamed())); | ||
| * | ||
| * factory = new DeserializationConstructorAndReflectiveTypeAdapterFactory(new ConstructorConstructor(), | ||
| * serializationStrategy, Excluder.DEFAULT, deserializationStrategy); | ||
| * | ||
| * gson = new GsonBuilder(serializationStrategy).registerTypeAdapterFactory(factory).create(); | ||
| * | ||
| * </pre> | ||
| * <p/> | ||
| * The above would work fine on the following class, which has no gson-specific annotations: | ||
| * <p/> | ||
| * <pre> | ||
| * private static class ImmutableAndVerifiedInCtor { | ||
| * final int foo; | ||
| * @Named("_bar") | ||
| * final int bar; | ||
| * | ||
| * @Inject | ||
| * ImmutableAndVerifiedInCtor(@Named("foo") int foo, @Named("_bar") int bar) { | ||
| * if (foo < 0) | ||
| * throw new IllegalArgumentException("negative!"); | ||
| * this.foo = foo; | ||
| * this.bar = bar; | ||
| * } | ||
| * } | ||
| * </pre> | ||
| * <p/> | ||
| * <br/> | ||
| * | ||
| * @author Adrian Cole | ||
| * @author Adam Lowe | ||
| */ | ||
| public final class DeserializationConstructorAndReflectiveTypeAdapterFactory implements TypeAdapterFactory { | ||
| private final ConstructorFieldNamingStrategy constructorFieldNamingPolicy; | ||
| private final ReflectiveTypeAdapterFactory delegateFactory; | ||
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| /** | ||
| * @param constructorConstructor passed through to delegate ReflectiveTypeAdapterFactory for serialization | ||
| * @param serializationFieldNamingPolicy passed through to delegate ReflectiveTypeAdapterFactory for serialization | ||
| * @param excluder passed through to delegate ReflectiveTypeAdapterFactory for serialization | ||
| * @param deserializationFieldNamingPolicy | ||
| * determines which constructor to use and how to determine field names for | ||
| * deserialization | ||
| * @see ReflectiveTypeAdapterFactory | ||
| */ | ||
| public DeserializationConstructorAndReflectiveTypeAdapterFactory( | ||
| ConstructorConstructor constructorConstructor, | ||
| FieldNamingStrategy serializationFieldNamingPolicy, | ||
| Excluder excluder, | ||
| ConstructorFieldNamingStrategy deserializationFieldNamingPolicy) { | ||
| this.constructorFieldNamingPolicy = checkNotNull(deserializationFieldNamingPolicy, "deserializationFieldNamingPolicy"); | ||
| this.delegateFactory = new ReflectiveTypeAdapterFactory(constructorConstructor, checkNotNull(serializationFieldNamingPolicy, "fieldNamingPolicy"), checkNotNull(excluder, "excluder")); | ||
| } | ||
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| @SuppressWarnings("unchecked") | ||
| public <T> TypeAdapter<T> create(Gson gson, final TypeToken<T> type) { | ||
| Class<? super T> raw = type.getRawType(); | ||
| Constructor<? super T> deserializationCtor = constructorFieldNamingPolicy.getDeserializationConstructor(raw); | ||
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| if (deserializationCtor == null) { | ||
| return null; // allow GSON to choose the correct Adapter (can't simply return delegateFactory.create()) | ||
| } else { | ||
| deserializationCtor.setAccessible(true); | ||
| return new DeserializeWithParameterizedConstructorSerializeWithDelegate<T>(delegateFactory.create(gson, type), deserializationCtor, | ||
| getParameterReaders(gson, type, deserializationCtor)); | ||
| } | ||
| } | ||
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| private final class DeserializeWithParameterizedConstructorSerializeWithDelegate<T> extends TypeAdapter<T> { | ||
| private final Constructor<? super T> parameterizedCtor; | ||
| private final Map<String, ParameterReader> parameterReaders; | ||
| private final TypeAdapter<T> delegate; | ||
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| private DeserializeWithParameterizedConstructorSerializeWithDelegate(TypeAdapter<T> delegate, | ||
| Constructor<? super T> parameterizedCtor, Map<String, ParameterReader> parameterReaders) { | ||
| this.delegate = delegate; | ||
| this.parameterizedCtor = parameterizedCtor; | ||
| this.parameterReaders = parameterReaders; | ||
| } | ||
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| @Override | ||
| public T read(JsonReader in) throws IOException { | ||
| if (in.peek() == JsonToken.NULL) { | ||
| in.nextNull(); | ||
| return null; | ||
| } | ||
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| Class<?>[] paramTypes = parameterizedCtor.getParameterTypes(); | ||
| Object[] ctorParams = new Object[paramTypes.length]; | ||
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| // TODO determine if we can drop this | ||
| for (int i = 0; i < paramTypes.length; i++) { | ||
| if (paramTypes[i] == boolean.class) { | ||
| ctorParams[i] = Boolean.FALSE; | ||
| } else if (paramTypes[i].isPrimitive()) { | ||
| ctorParams[i] = 0; | ||
| } | ||
| } | ||
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| try { | ||
| in.beginObject(); | ||
| while (in.hasNext()) { | ||
| String name = in.nextName(); | ||
| ParameterReader parameter = parameterReaders.get(name); | ||
| if (parameter == null) { | ||
| in.skipValue(); | ||
| } else { | ||
| Object value = parameter.read(in); | ||
| if (value != null) ctorParams[parameter.index] = value; | ||
| } | ||
| } | ||
| } catch (IllegalStateException e) { | ||
| throw new JsonSyntaxException(e); | ||
| } | ||
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| for (int i = 0; i < paramTypes.length; i++) { | ||
| if (paramTypes[i].isPrimitive()) { | ||
| checkArgument(ctorParams[i] != null, "Primative param[" + i + "] in constructor " + parameterizedCtor | ||
| + " cannot be absent!"); | ||
| } | ||
| } | ||
| in.endObject(); | ||
| return newInstance(ctorParams); | ||
| } | ||
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| /** | ||
| * pass to delegate | ||
| */ | ||
| @Override | ||
| public void write(JsonWriter out, T value) throws IOException { | ||
| delegate.write(out, value); | ||
| } | ||
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| @SuppressWarnings("unchecked") | ||
| private T newInstance(Object[] ctorParams) throws AssertionError { | ||
| try { | ||
| return (T) parameterizedCtor.newInstance(ctorParams); | ||
| } catch (InstantiationException e) { | ||
| throw new AssertionError(e); | ||
| } catch (IllegalAccessException e) { | ||
| throw new AssertionError(e); | ||
| } catch (InvocationTargetException e) { | ||
| if (e.getCause() instanceof RuntimeException) | ||
| throw RuntimeException.class.cast(e.getCause()); | ||
| throw new AssertionError(e); | ||
| } | ||
| } | ||
| } | ||
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| // logic borrowed from ReflectiveTypeAdapterFactory | ||
| static class ParameterReader<T> { | ||
| final String name; | ||
| final int index; | ||
| final TypeAdapter<T> typeAdapter; | ||
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| ParameterReader(String name, int index, TypeAdapter<T> typeAdapter) { | ||
| this.name = name; | ||
| this.index = index; | ||
| this.typeAdapter = typeAdapter; | ||
| } | ||
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| public Object read(JsonReader reader) throws IOException { | ||
| return typeAdapter.read(reader); | ||
| } | ||
| } | ||
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| @SuppressWarnings("unchecked") | ||
| private Map<String, ParameterReader> getParameterReaders(Gson context, TypeToken<?> declaring, Constructor<?> constructor) { | ||
| Map<String, ParameterReader> result = new LinkedHashMap<String, ParameterReader>(); | ||
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| for (int index = 0; index < constructor.getGenericParameterTypes().length; index++) { | ||
| Type parameterType = getTypeOfConstructorParameter(declaring, constructor, index); | ||
| TypeAdapter<?> adapter = context.getAdapter(TypeToken.get(parameterType)); | ||
| String parameterName = constructorFieldNamingPolicy.translateName(constructor, index); | ||
| checkArgument(parameterName != null, constructor + " parameter " + 0 + " failed to be named by " + constructorFieldNamingPolicy); | ||
| ParameterReader parameterReader = new ParameterReader(parameterName, index, adapter); | ||
| ParameterReader previous = result.put(parameterReader.name, parameterReader); | ||
| checkArgument(previous == null, constructor + " declares multiple JSON parameters named " + parameterReader.name); | ||
| } | ||
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| return result; | ||
| } | ||
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| private Type getTypeOfConstructorParameter(TypeToken<?> declaring, Constructor<?> constructor, int index) { | ||
| Type genericParameter = constructor.getGenericParameterTypes()[index]; | ||
| return $Gson$Types.resolve(declaring.getType(), declaring.getRawType(), genericParameter); | ||
| } | ||
| } |
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