265 lines
9.3 KiB
Java
265 lines
9.3 KiB
Java
/*
|
|
* 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<>();
|
|
* 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;
|
|
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<>(context, keyTypeAdapter, keyType);
|
|
this.valueTypeAdapter =
|
|
new TypeAdapterRuntimeTypeWrapper<>(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<>(map.size());
|
|
|
|
List<V> values = new ArrayList<>(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, size = keys.size(); i < 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, size = keys.size(); i < 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();
|
|
}
|
|
}
|
|
}
|
|
}
|