Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.io.network.util;
020
021import org.apache.reef.wake.remote.Codec;
022
023import java.io.*;
024import java.util.ArrayList;
025import java.util.Arrays;
026import java.util.List;
027import java.util.logging.Level;
028import java.util.logging.Logger;
029
030public final class ListCodec<T> implements Codec<List<T>> {
031
032  private static final Logger LOG = Logger.getLogger(ListCodec.class.getName());
033
034  private final Codec<T> codec;
035
036  public ListCodec(final Codec<T> codec) {
037    super();
038    this.codec = codec;
039  }
040
041  public static void main(final String[] args) {
042    final List<String> arrList = Arrays.asList(
043        new String[]{"One", "Two", "Three", "Four", "Five"});
044    LOG.log(Level.FINEST, "Input: {0}", arrList);
045    final ListCodec<String> lstCodec = new ListCodec<>(new StringCodec());
046    final byte[] bytes = lstCodec.encode(arrList);
047    LOG.log(Level.FINEST, "Output: {0}", lstCodec.decode(bytes));
048  }
049
050  @Override
051  public byte[] encode(final List<T> list) {
052    try (final ByteArrayOutputStream baos = new ByteArrayOutputStream();
053         final DataOutputStream daos = new DataOutputStream(baos)) {
054      for (final T t : list) {
055        final byte[] tBytes = this.codec.encode(t);
056        daos.writeInt(tBytes.length);
057        daos.write(tBytes);
058      }
059      return baos.toByteArray();
060    } catch (final IOException ex) {
061      LOG.log(Level.WARNING, "Error in list encoding", ex);
062      throw new RuntimeException(ex);
063    }
064  }
065
066  @Override
067  public List<T> decode(final byte[] list) {
068    final List<T> result = new ArrayList<>();
069    try (final DataInputStream dais = new DataInputStream(new ByteArrayInputStream(list))) {
070      while (dais.available() > 0) {
071        final int length = dais.readInt();
072        final byte[] tBytes = new byte[length];
073        dais.readFully(tBytes);
074        final T t = this.codec.decode(tBytes);
075        result.add(t);
076      }
077      return result;
078    } catch (final IOException ex) {
079      LOG.log(Level.WARNING, "Error in list decoding", ex);
080      throw new RuntimeException(ex);
081    }
082  }
083}