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org.bson.codecs.MapCodec Maven / Gradle / Ivy
/*
* Copyright 2008-present MongoDB, 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 org.bson.codecs;
import org.bson.BsonReader;
import org.bson.BsonType;
import org.bson.BsonWriter;
import org.bson.Transformer;
import org.bson.UuidRepresentation;
import org.bson.codecs.configuration.CodecRegistry;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import static java.util.Arrays.asList;
import static org.bson.assertions.Assertions.notNull;
import static org.bson.codecs.configuration.CodecRegistries.fromProviders;
/**
* A Codec for Map instances.
*
* @since 3.5
*/
public class MapCodec implements Codec>, OverridableUuidRepresentationCodec> {
private static final CodecRegistry DEFAULT_REGISTRY = fromProviders(asList(new ValueCodecProvider(), new BsonValueCodecProvider(),
new DocumentCodecProvider(), new IterableCodecProvider(), new MapCodecProvider()));
private static final BsonTypeClassMap DEFAULT_BSON_TYPE_CLASS_MAP = new BsonTypeClassMap();
private final BsonTypeCodecMap bsonTypeCodecMap;
private final CodecRegistry registry;
private final Transformer valueTransformer;
private final UuidRepresentation uuidRepresentation;
/**
* Construct a new instance with a default {@code CodecRegistry}
*/
public MapCodec() {
this(DEFAULT_REGISTRY);
}
/**
Construct a new instance with the given registry
*
* @param registry the registry
*/
public MapCodec(final CodecRegistry registry) {
this(registry, DEFAULT_BSON_TYPE_CLASS_MAP);
}
/**
* Construct a new instance with the given registry and BSON type class map.
*
* @param registry the registry
* @param bsonTypeClassMap the BSON type class map
*/
public MapCodec(final CodecRegistry registry, final BsonTypeClassMap bsonTypeClassMap) {
this(registry, bsonTypeClassMap, null);
}
/**
* Construct a new instance with the given registry and BSON type class map. The transformer is applied as a last step when decoding
* values, which allows users of this codec to control the decoding process. For example, a user of this class could substitute a
* value decoded as a Document with an instance of a special purpose class (e.g., one representing a DBRef in MongoDB).
*
* @param registry the registry
* @param bsonTypeClassMap the BSON type class map
* @param valueTransformer the value transformer to use as a final step when decoding the value of any field in the map
*/
public MapCodec(final CodecRegistry registry, final BsonTypeClassMap bsonTypeClassMap, final Transformer valueTransformer) {
this(registry, new BsonTypeCodecMap(notNull("bsonTypeClassMap", bsonTypeClassMap), registry), valueTransformer,
UuidRepresentation.JAVA_LEGACY);
}
private MapCodec(final CodecRegistry registry, final BsonTypeCodecMap bsonTypeCodecMap, final Transformer valueTransformer,
final UuidRepresentation uuidRepresentation) {
this.registry = notNull("registry", registry);
this.bsonTypeCodecMap = bsonTypeCodecMap;
this.valueTransformer = valueTransformer != null ? valueTransformer : new Transformer() {
@Override
public Object transform(final Object value) {
return value;
}
};
this.uuidRepresentation = uuidRepresentation;
}
@Override
public Codec> withUuidRepresentation(final UuidRepresentation uuidRepresentation) {
return new MapCodec(registry, bsonTypeCodecMap, valueTransformer, uuidRepresentation);
}
@Override
public void encode(final BsonWriter writer, final Map map, final EncoderContext encoderContext) {
writer.writeStartDocument();
for (final Map.Entry entry : map.entrySet()) {
writer.writeName(entry.getKey());
writeValue(writer, encoderContext, entry.getValue());
}
writer.writeEndDocument();
}
@Override
public Map decode(final BsonReader reader, final DecoderContext decoderContext) {
Map map = new HashMap();
reader.readStartDocument();
while (reader.readBsonType() != BsonType.END_OF_DOCUMENT) {
String fieldName = reader.readName();
map.put(fieldName, readValue(reader, decoderContext));
}
reader.readEndDocument();
return map;
}
@SuppressWarnings({"unchecked", "rawtypes"})
@Override
public Class> getEncoderClass() {
return (Class>) ((Class) Map.class);
}
private Object readValue(final BsonReader reader, final DecoderContext decoderContext) {
BsonType bsonType = reader.getCurrentBsonType();
if (bsonType == BsonType.NULL) {
reader.readNull();
return null;
} else if (bsonType == BsonType.ARRAY) {
return decoderContext.decodeWithChildContext(registry.get(List.class), reader);
} else if (bsonType == BsonType.BINARY && reader.peekBinarySize() == 16) {
Codec codec = bsonTypeCodecMap.get(bsonType);
switch (reader.peekBinarySubType()) {
case 3:
if (uuidRepresentation == UuidRepresentation.JAVA_LEGACY
|| uuidRepresentation == UuidRepresentation.C_SHARP_LEGACY
|| uuidRepresentation == UuidRepresentation.PYTHON_LEGACY) {
codec = registry.get(UUID.class);
}
break;
case 4:
if (uuidRepresentation == UuidRepresentation.JAVA_LEGACY || uuidRepresentation == UuidRepresentation.STANDARD) {
codec = registry.get(UUID.class);
}
break;
default:
break;
}
return decoderContext.decodeWithChildContext(codec, reader);
}
return valueTransformer.transform(bsonTypeCodecMap.get(bsonType).decode(reader, decoderContext));
}
@SuppressWarnings({"unchecked", "rawtypes"})
private void writeValue(final BsonWriter writer, final EncoderContext encoderContext, final Object value) {
if (value == null) {
writer.writeNull();
} else {
Codec codec = registry.get(value.getClass());
encoderContext.encodeWithChildContext(codec, writer, value);
}
}
}