gson/com/google/gson/internal/bind/ArrayTypeAdapter.java

   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
  17 package com.google.gson.internal.bind;
  18
  19 import java.io.IOException;
  20 import java.lang.reflect.Array;
  21 import java.lang.reflect.GenericArrayType;
  22 import java.lang.reflect.Type;
  23 import java.util.ArrayList;
  24 import java.util.List;
  25
  26 import com.google.gson.Gson;
  27 import com.google.gson.TypeAdapter;
  28 import com.google.gson.TypeAdapterFactory;
  29 import com.google.gson.internal.$Gson$Types;
  30 import com.google.gson.reflect.TypeToken;
  31 import com.google.gson.stream.JsonReader;
  32 import com.google.gson.stream.JsonToken;
  33 import com.google.gson.stream.JsonWriter;
  34
  35 /**
  36  * Adapt an array of objects.
  37  */
  38 public final class ArrayTypeAdapter<E> extends TypeAdapter<Object> {
  39   public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
  40     @SuppressWarnings({"unchecked", "rawtypes"})
  41     public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
  42       Type type = typeToken.getType();
  43       if (!(type instanceof GenericArrayType || type instanceof Class && ((Class<?>) type).isArray())) {
  44         return null;
  45       }
  46
  47       Type componentType = $Gson$Types.getArrayComponentType(type);
  48       TypeAdapter<?> componentTypeAdapter = gson.getAdapter(TypeToken.get(componentType));
  49       return new ArrayTypeAdapter(
  50               gson, componentTypeAdapter, $Gson$Types.getRawType(componentType));
  51     }
  52   };
  53
  54   private final Class<E> componentType;
  55   private final TypeAdapter<E> componentTypeAdapter;
  56
  57   public ArrayTypeAdapter(Gson context, TypeAdapter<E> componentTypeAdapter, Class<E> componentType) {
  58     this.componentTypeAdapter =
  59       new TypeAdapterRuntimeTypeWrapper<E>(context, componentTypeAdapter, componentType);
  60     this.componentType = componentType;
  61   }
  62
  63   public Object read(JsonReader in) throws IOException {
  64     if (in.peek() == JsonToken.NULL) {
  65       in.nextNull();
  66       return null;
  67     }
  68
  69     List<E> list = new ArrayList<E>();
  70     in.beginArray();
  71     while (in.hasNext()) {
  72       E instance = componentTypeAdapter.read(in);
  73       list.add(instance);
  74     }
  75     in.endArray();
  76     Object array = Array.newInstance(componentType, list.size());
  77     for (int i = 0; i < list.size(); i++) {
  78       Array.set(array, i, list.get(i));
  79     }
  80     return array;
  81   }
  82
  83   @SuppressWarnings("unchecked")
  84   @Override public void write(JsonWriter out, Object array) throws IOException {
  85     if (array == null) {
  86       out.nullValue();
  87       return;
  88     }
  89
  90     out.beginArray();
  91     for (int i = 0, length = Array.getLength(array); i < length; i++) {
  92       E value = (E) Array.get(array, i);
  93       componentTypeAdapter.write(out, value);
  94     }
  95     out.endArray();
  96   }
  97 }