AvroByteArrayConverter.java

/*
 * Copyright 2014-2016 CyberVision, 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.kaaproject.kaa.common.avro;

import org.apache.avro.io.BinaryDecoder;
import org.apache.avro.io.BinaryEncoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;
import org.apache.avro.specific.SpecificRecordBase;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

/**
 * The Class AvroByteArrayConverter is used to convert
 * {#link org.apache.avro.specific.SpecificRecordBase specific Avro records} to/from bytes.
 * NOT Thread safe.
 *
 * @param <T> the generic type that extends SpecificRecordBase
 * @author Andrew Shvayka
 */
public class AvroByteArrayConverter<T extends SpecificRecordBase> {
  SpecificDatumReader<T> avroReader;
  SpecificDatumWriter<T> avroWriter;
  BinaryEncoder encoder;
  BinaryDecoder decoder;

  /**
   * Instantiates a new Avro byte array converter based on class.
   *
   * @param typeParameterClass the type parameter class
   */
  public AvroByteArrayConverter(Class<T> typeParameterClass) {
    super();
    avroReader = new SpecificDatumReader<T>(typeParameterClass);
    avroWriter = new SpecificDatumWriter<T>(typeParameterClass);
  }

  /**
   * Converts object to byte array
   *
   * @param avroObject the avro object
   * @return the byte[] result of conversion
   * @throws IOException Signals that an I/O exception has occurred.
   */
  public byte[] toByteArray(T avroObject) throws IOException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    encoder = EncoderFactory.get().binaryEncoder(baos, encoder);
    avroWriter.write(avroObject, encoder);
    encoder.flush();
    return baos.toByteArray();
  }

  /**
   * Creates object from byte array
   *
   * @param data the data
   * @return the result of conversion
   * @throws IOException Signals that an I/O exception has occurred.
   */
  public T fromByteArray(byte[] data) throws IOException {
    return fromByteArray(data, null);
  }

  /**
   * Creates object from byte array
   *
   * @param data  the data
   * @param reuse object to reuse
   * @return the result of conversion
   * @throws IOException Signals that an I/O exception has occurred.
   */
  public T fromByteArray(byte[] data, T reuse) throws IOException {
    decoder = DecoderFactory.get().binaryDecoder(data, decoder);
    return avroReader.read(reuse, decoder);
  }
}