com.datasalt.utils.commons.WritableUtils.java Source code

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Here is the source code for com.datasalt.utils.commons.WritableUtils.java

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/**
 * Copyright [2011] [Datasalt Systems S.L.]
 *
 * 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.datasalt.utils.commons;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

import org.apache.hadoop.io.Writable;

/**
 * Class with utilities for {@link Writable} classes
 * 
 * @author ivan
 */
public class WritableUtils {

    /**
    * Serialize writable
    */
    public static byte[] serialize(Writable datum) throws IOException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        DataOutputStream dos = new DataOutputStream(bos);

        datum.write(dos);
        return bos.toByteArray();
    }

    /**
    * Deserialize Writables
    */
    public static Writable deserialize(Writable datum, byte[] bytes) throws IOException {
        ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
        DataInputStream dis = new DataInputStream(bis);

        datum.readFields(dis);

        dis.close();
        return datum;
    }

    static ThreadLocal<ByteBuffer> shortBuffer = new ThreadLocal<ByteBuffer>() {

        @Override
        protected ByteBuffer initialValue() {
            return ByteBuffer.allocate(2);
        }

    };

    /**
     * Reads a short from the bytes array start position.
     */
    public static short readShort(byte[] bytes, int start) {
        ByteBuffer bb = shortBuffer.get();
        bb.clear();
        bb.put(bytes[start + 0]);
        bb.put(bytes[start + 1]);
        return bb.getShort(0);
    }
}