com.datastax.driver.extras.codecs.MappingCodec Maven / Gradle / Ivy
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Extended functionality for the Java driver.
/*
* Copyright (C) 2012-2015 DataStax 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.datastax.driver.extras.codecs;
import com.datastax.driver.core.ProtocolVersion;
import com.datastax.driver.core.TypeCodec;
import com.datastax.driver.core.exceptions.InvalidTypeException;
import com.google.common.reflect.TypeToken;
import java.nio.ByteBuffer;
/**
* An abstract {@link TypeCodec} that maps a Java Pojo to another Java object
* that can in turn be serialized into a CQL type.
* This can serve as a base for libraries dealing with Pojo mappings.
*
* This codec can be seen as a convenience base class for libraries
* dealing with Pojo-to-Pojo mappings, but it comes
* with a performance penalty: each Java object is serialized
* in two steps: first to an intermediate object, and then to a {@link ByteBuffer},
* which means that each serialization actually incurs in two potentially
* expensive operations being carried.
*
* If such operations are really expensive, and your mapping library is capable
* of serializing objects directly to {@link ByteBuffer}s,
* consider writing your own codec instead of using this one.
*
* @param The "outer" (user-facing) Java type
* @param The "inner" (Cassandra-facing, intermediary) Java type
*/
public abstract class MappingCodec extends TypeCodec {
protected final TypeCodec innerCodec;
public MappingCodec(TypeCodec innerCodec, Class javaType) {
this(innerCodec, TypeToken.of(javaType));
}
public MappingCodec(TypeCodec innerCodec, TypeToken javaType) {
super(innerCodec.getCqlType(), javaType);
this.innerCodec = innerCodec;
}
@Override
public ByteBuffer serialize(O value, ProtocolVersion protocolVersion) throws InvalidTypeException {
return innerCodec.serialize(serialize(value), protocolVersion);
}
@Override
public O deserialize(ByteBuffer bytes, ProtocolVersion protocolVersion) throws InvalidTypeException {
return deserialize(innerCodec.deserialize(bytes, protocolVersion));
}
@Override
public O parse(String value) throws InvalidTypeException {
return value == null || value.isEmpty() || value.equalsIgnoreCase("NULL") ? null : deserialize(innerCodec.parse(value));
}
@Override
public String format(O value) throws InvalidTypeException {
return value == null ? null : innerCodec.format(serialize(value));
}
protected abstract O deserialize(I value);
protected abstract I serialize(O value);
}