org.apache.hadoop.io.serializer.WritableSerialization Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.hadoop.io.serializer;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.util.ReflectionUtils;
/**
* A {@link Serialization} for {@link Writable}s that delegates to
* {@link Writable#write(java.io.DataOutput)} and
* {@link Writable#readFields(java.io.DataInput)}.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class WritableSerialization extends Configured
implements Serialization {
static class WritableDeserializer extends Configured
implements Deserializer {
private Class writableClass;
private DataInputStream dataIn;
public WritableDeserializer(Configuration conf, Class c) {
setConf(conf);
this.writableClass = c;
}
@Override
public void open(InputStream in) {
if (in instanceof DataInputStream) {
dataIn = (DataInputStream) in;
} else {
dataIn = new DataInputStream(in);
}
}
@Override
public Writable deserialize(Writable w) throws IOException {
Writable writable;
if (w == null) {
writable
= (Writable) ReflectionUtils.newInstance(writableClass, getConf());
} else {
writable = w;
}
writable.readFields(dataIn);
return writable;
}
@Override
public void close() throws IOException {
dataIn.close();
}
}
static class WritableSerializer extends Configured implements
Serializer {
private DataOutputStream dataOut;
@Override
public void open(OutputStream out) {
if (out instanceof DataOutputStream) {
dataOut = (DataOutputStream) out;
} else {
dataOut = new DataOutputStream(out);
}
}
@Override
public void serialize(Writable w) throws IOException {
w.write(dataOut);
}
@Override
public void close() throws IOException {
dataOut.close();
}
}
@InterfaceAudience.Private
@Override
public boolean accept(Class c) {
return Writable.class.isAssignableFrom(c);
}
@InterfaceAudience.Private
@Override
public Serializer getSerializer(Class c) {
return new WritableSerializer();
}
@InterfaceAudience.Private
@Override
public Deserializer getDeserializer(Class c) {
return new WritableDeserializer(getConf(), c);
}
}