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1 | /* |
2 | * Copyright (C) 2011 Google Inc. | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | package com.google.gson.internal.bind; | |
17 | ||
18 | import com.google.gson.Gson; | |
19 | import com.google.gson.TypeAdapter; | |
20 | import com.google.gson.reflect.TypeToken; | |
21 | import com.google.gson.stream.JsonReader; | |
22 | import com.google.gson.stream.JsonWriter; | |
23 | import java.io.IOException; | |
24 | import java.lang.reflect.Type; | |
25 | import java.lang.reflect.TypeVariable; | |
26 | ||
27 | final class TypeAdapterRuntimeTypeWrapper<T> extends TypeAdapter<T> { | |
28 | private final Gson context; | |
29 | private final TypeAdapter<T> delegate; | |
30 | private final Type type; | |
31 | ||
32 | TypeAdapterRuntimeTypeWrapper(Gson context, TypeAdapter<T> delegate, Type type) { | |
33 | this.context = context; | |
34 | this.delegate = delegate; | |
35 | this.type = type; | |
36 | } | |
37 | ||
38 | @Override | |
39 | public T read(JsonReader in) throws IOException { | |
40 | return delegate.read(in); | |
41 | } | |
42 | ||
43 | @SuppressWarnings({"rawtypes", "unchecked"}) | |
44 | @Override | |
45 | public void write(JsonWriter out, T value) throws IOException { | |
46 | // Order of preference for choosing type adapters | |
47 | // First preference: a type adapter registered for the runtime type | |
48 | // Second preference: a type adapter registered for the declared type | |
49 | // Third preference: reflective type adapter for the runtime type (if it is a sub class of the declared type) | |
50 | // Fourth preference: reflective type adapter for the declared type | |
51 | ||
52 | TypeAdapter chosen = delegate; | |
53 | Type runtimeType = getRuntimeTypeIfMoreSpecific(type, value); | |
54 | if (runtimeType != type) { | |
55 | TypeAdapter runtimeTypeAdapter = context.getAdapter(TypeToken.get(runtimeType)); | |
56 | if (!(runtimeTypeAdapter instanceof ReflectiveTypeAdapterFactory.Adapter)) { | |
57 | // The user registered a type adapter for the runtime type, so we will use that | |
58 | chosen = runtimeTypeAdapter; | |
59 | } else if (!(delegate instanceof ReflectiveTypeAdapterFactory.Adapter)) { | |
60 | // The user registered a type adapter for Base class, so we prefer it over the | |
61 | // reflective type adapter for the runtime type | |
62 | chosen = delegate; | |
63 | } else { | |
64 | // Use the type adapter for runtime type | |
65 | chosen = runtimeTypeAdapter; | |
66 | } | |
67 | } | |
68 | chosen.write(out, value); | |
69 | } | |
70 | ||
71 | /** | |
72 | * Finds a compatible runtime type if it is more specific | |
73 | */ | |
74 | private Type getRuntimeTypeIfMoreSpecific(Type type, Object value) { | |
75 | if (value != null | |
76 | && (type == Object.class || type instanceof TypeVariable<?> || type instanceof Class<?>)) { | |
77 | type = value.getClass(); | |
78 | } | |
79 | return type; | |
80 | } | |
81 | } |