| /* |
| * Copyright (C) 2011 Google Inc. |
| * |
| * Licensed 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 com.google.gson.internal.bind; |
| |
| import com.google.gson.Gson; |
| import com.google.gson.JsonElement; |
| import com.google.gson.JsonPrimitive; |
| 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.JsonReaderInternalAccess; |
| import com.google.gson.internal.ObjectConstructor; |
| import com.google.gson.internal.Streams; |
| import com.google.gson.reflect.TypeToken; |
| import com.google.gson.stream.JsonReader; |
| import com.google.gson.stream.JsonToken; |
| import com.google.gson.stream.JsonWriter; |
| import java.io.IOException; |
| import java.lang.reflect.Type; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Map; |
| |
| /** |
| * Adapts maps to either JSON objects or JSON arrays. |
| * |
| * <h3>Maps as JSON objects</h3> |
| * For primitive keys or when complex map key serialization is not enabled, this |
| * converts Java {@link Map Maps} to JSON Objects. This requires that map keys |
| * can be serialized as strings; this is insufficient for some key types. For |
| * example, consider a map whose keys are points on a grid. The default JSON |
| * form encodes reasonably: <pre> {@code |
| * Map<Point, String> original = new LinkedHashMap<Point, String>(); |
| * original.put(new Point(5, 6), "a"); |
| * original.put(new Point(8, 8), "b"); |
| * System.out.println(gson.toJson(original, type)); |
| * }</pre> |
| * The above code prints this JSON object:<pre> {@code |
| * { |
| * "(5,6)": "a", |
| * "(8,8)": "b" |
| * } |
| * }</pre> |
| * But GSON is unable to deserialize this value because the JSON string name is |
| * just the {@link Object#toString() toString()} of the map key. Attempting to |
| * convert the above JSON to an object fails with a parse exception: |
| * <pre>com.google.gson.JsonParseException: Expecting object found: "(5,6)" |
| * at com.google.gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler |
| * at com.google.gson.ObjectNavigator.navigateClassFields |
| * ...</pre> |
| * |
| * <h3>Maps as JSON arrays</h3> |
| * An alternative approach taken by this type adapter when it is required and |
| * complex map key serialization is enabled is to encode maps as arrays of map |
| * entries. Each map entry is a two element array containing a key and a value. |
| * This approach is more flexible because any type can be used as the map's key; |
| * not just strings. But it's also less portable because the receiver of such |
| * JSON must be aware of the map entry convention. |
| * |
| * <p>Register this adapter when you are creating your GSON instance. |
| * <pre> {@code |
| * Gson gson = new GsonBuilder() |
| * .registerTypeAdapter(Map.class, new MapAsArrayTypeAdapter()) |
| * .create(); |
| * }</pre> |
| * This will change the structure of the JSON emitted by the code above. Now we |
| * get an array. In this case the arrays elements are map entries: |
| * <pre> {@code |
| * [ |
| * [ |
| * { |
| * "x": 5, |
| * "y": 6 |
| * }, |
| * "a", |
| * ], |
| * [ |
| * { |
| * "x": 8, |
| * "y": 8 |
| * }, |
| * "b" |
| * ] |
| * ] |
| * }</pre> |
| * This format will serialize and deserialize just fine as long as this adapter |
| * is registered. |
| */ |
| public final class MapTypeAdapterFactory implements TypeAdapterFactory { |
| private final ConstructorConstructor constructorConstructor; |
| private final boolean complexMapKeySerialization; |
| |
| public MapTypeAdapterFactory(ConstructorConstructor constructorConstructor, |
| boolean complexMapKeySerialization) { |
| this.constructorConstructor = constructorConstructor; |
| this.complexMapKeySerialization = complexMapKeySerialization; |
| } |
| |
| @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) { |
| Type type = typeToken.getType(); |
| |
| Class<? super T> rawType = typeToken.getRawType(); |
| if (!Map.class.isAssignableFrom(rawType)) { |
| return null; |
| } |
| |
| Class<?> rawTypeOfSrc = $Gson$Types.getRawType(type); |
| Type[] keyAndValueTypes = $Gson$Types.getMapKeyAndValueTypes(type, rawTypeOfSrc); |
| TypeAdapter<?> keyAdapter = getKeyAdapter(gson, keyAndValueTypes[0]); |
| TypeAdapter<?> valueAdapter = gson.getAdapter(TypeToken.get(keyAndValueTypes[1])); |
| ObjectConstructor<T> constructor = constructorConstructor.get(typeToken); |
| |
| @SuppressWarnings({"unchecked", "rawtypes"}) |
| // we don't define a type parameter for the key or value types |
| TypeAdapter<T> result = new Adapter(gson, keyAndValueTypes[0], keyAdapter, |
| keyAndValueTypes[1], valueAdapter, constructor); |
| return result; |
| } |
| |
| /** |
| * Returns a type adapter that writes the value as a string. |
| */ |
| private TypeAdapter<?> getKeyAdapter(Gson context, Type keyType) { |
| return (keyType == boolean.class || keyType == Boolean.class) |
| ? TypeAdapters.BOOLEAN_AS_STRING |
| : context.getAdapter(TypeToken.get(keyType)); |
| } |
| |
| private final class Adapter<K, V> extends TypeAdapter<Map<K, V>> { |
| private final TypeAdapter<K> keyTypeAdapter; |
| private final TypeAdapter<V> valueTypeAdapter; |
| private final ObjectConstructor<? extends Map<K, V>> constructor; |
| |
| public Adapter(Gson context, Type keyType, TypeAdapter<K> keyTypeAdapter, |
| Type valueType, TypeAdapter<V> valueTypeAdapter, |
| ObjectConstructor<? extends Map<K, V>> constructor) { |
| this.keyTypeAdapter = |
| new TypeAdapterRuntimeTypeWrapper<K>(context, keyTypeAdapter, keyType); |
| this.valueTypeAdapter = |
| new TypeAdapterRuntimeTypeWrapper<V>(context, valueTypeAdapter, valueType); |
| this.constructor = constructor; |
| } |
| |
| @Override public Map<K, V> read(JsonReader in) throws IOException { |
| JsonToken peek = in.peek(); |
| if (peek == JsonToken.NULL) { |
| in.nextNull(); |
| return null; |
| } |
| |
| Map<K, V> map = constructor.construct(); |
| |
| if (peek == JsonToken.BEGIN_ARRAY) { |
| in.beginArray(); |
| while (in.hasNext()) { |
| in.beginArray(); // entry array |
| K key = keyTypeAdapter.read(in); |
| V value = valueTypeAdapter.read(in); |
| V replaced = map.put(key, value); |
| if (replaced != null) { |
| throw new JsonSyntaxException("duplicate key: " + key); |
| } |
| in.endArray(); |
| } |
| in.endArray(); |
| } else { |
| in.beginObject(); |
| while (in.hasNext()) { |
| JsonReaderInternalAccess.INSTANCE.promoteNameToValue(in); |
| K key = keyTypeAdapter.read(in); |
| V value = valueTypeAdapter.read(in); |
| V replaced = map.put(key, value); |
| if (replaced != null) { |
| throw new JsonSyntaxException("duplicate key: " + key); |
| } |
| } |
| in.endObject(); |
| } |
| return map; |
| } |
| |
| @Override public void write(JsonWriter out, Map<K, V> map) throws IOException { |
| if (map == null) { |
| out.nullValue(); |
| return; |
| } |
| |
| if (!complexMapKeySerialization) { |
| out.beginObject(); |
| for (Map.Entry<K, V> entry : map.entrySet()) { |
| out.name(String.valueOf(entry.getKey())); |
| valueTypeAdapter.write(out, entry.getValue()); |
| } |
| out.endObject(); |
| return; |
| } |
| |
| boolean hasComplexKeys = false; |
| List<JsonElement> keys = new ArrayList<JsonElement>(map.size()); |
| |
| List<V> values = new ArrayList<V>(map.size()); |
| for (Map.Entry<K, V> entry : map.entrySet()) { |
| JsonElement keyElement = keyTypeAdapter.toJsonTree(entry.getKey()); |
| keys.add(keyElement); |
| values.add(entry.getValue()); |
| hasComplexKeys |= keyElement.isJsonArray() || keyElement.isJsonObject(); |
| } |
| |
| if (hasComplexKeys) { |
| out.beginArray(); |
| for (int i = 0; i < keys.size(); i++) { |
| out.beginArray(); // entry array |
| Streams.write(keys.get(i), out); |
| valueTypeAdapter.write(out, values.get(i)); |
| out.endArray(); |
| } |
| out.endArray(); |
| } else { |
| out.beginObject(); |
| for (int i = 0; i < keys.size(); i++) { |
| JsonElement keyElement = keys.get(i); |
| out.name(keyToString(keyElement)); |
| valueTypeAdapter.write(out, values.get(i)); |
| } |
| out.endObject(); |
| } |
| } |
| |
| private String keyToString(JsonElement keyElement) { |
| if (keyElement.isJsonPrimitive()) { |
| JsonPrimitive primitive = keyElement.getAsJsonPrimitive(); |
| if (primitive.isNumber()) { |
| return String.valueOf(primitive.getAsNumber()); |
| } else if (primitive.isBoolean()) { |
| return Boolean.toString(primitive.getAsBoolean()); |
| } else if (primitive.isString()) { |
| return primitive.getAsString(); |
| } else { |
| throw new AssertionError(); |
| } |
| } else if (keyElement.isJsonNull()) { |
| return "null"; |
| } else { |
| throw new AssertionError(); |
| } |
| } |
| } |
| } |