gson/com/google/gson/internal/bind/ObjectTypeAdapter.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 com.google.gson.Gson;
  20 import com.google.gson.TypeAdapter;
  21 import com.google.gson.TypeAdapterFactory;
  22 import com.google.gson.internal.LinkedTreeMap;
  23 import com.google.gson.reflect.TypeToken;
  24 import com.google.gson.stream.JsonReader;
  25 import com.google.gson.stream.JsonToken;
  26 import com.google.gson.stream.JsonWriter;
  27
  28 import java.io.IOException;
  29 import java.util.ArrayList;
  30 import java.util.List;
  31 import java.util.Map;
  32
  33 /**
  34  * Adapts types whose static type is only 'Object'. Uses getClass() on
  35  * serialization and a primitive/Map/List on deserialization.
  36  */
  37 public final class ObjectTypeAdapter extends TypeAdapter<Object> {
  38   public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
  39     @SuppressWarnings("unchecked")
  40     public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
  41       if (type.getRawType() == Object.class) {
  42         return (TypeAdapter<T>) new ObjectTypeAdapter(gson);
  43       }
  44       return null;
  45     }
  46   };
  47
  48   private final Gson gson;
  49
  50   private ObjectTypeAdapter(Gson gson) {
  51     this.gson = gson;
  52   }
  53
  54   @Override public Object read(JsonReader in) throws IOException {
  55     JsonToken token = in.peek();
  56     switch (token) {
  57     case BEGIN_ARRAY:
  58       List<Object> list = new ArrayList<Object>();
  59       in.beginArray();
  60       while (in.hasNext()) {
  61         list.add(read(in));
  62       }
  63       in.endArray();
  64       return list;
  65
  66     case BEGIN_OBJECT:
  67       Map<String, Object> map = new LinkedTreeMap<String, Object>();
  68       in.beginObject();
  69       while (in.hasNext()) {
  70         map.put(in.nextName(), read(in));
  71       }
  72       in.endObject();
  73       return map;
  74
  75     case STRING:
  76       return in.nextString();
  77
  78     case NUMBER:
  79       return in.nextDouble();
  80
  81     case BOOLEAN:
  82       return in.nextBoolean();
  83
  84     case NULL:
  85       in.nextNull();
  86       return null;
  87
  88     default:
  89       throw new IllegalStateException();
  90     }
  91   }
  92
  93   @SuppressWarnings("unchecked")
  94   @Override public void write(JsonWriter out, Object value) throws IOException {
  95     if (value == null) {
  96       out.nullValue();
  97       return;
  98     }
  99
 100     TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
 101     if (typeAdapter instanceof ObjectTypeAdapter) {
 102       out.beginObject();
 103       out.endObject();
 104       return;
 105     }
 106
 107     typeAdapter.write(out, value);
 108   }
 109 }