--- /dev/null
+/*
+ * 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;
+ }
+
+ 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;
+ }
+
+ 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;
+ }
+
+ 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();
+ }
+ }
+ }
+}
projects / unical.git / blobdiff