CJDBCStream.java

/**
 * C-JDBC: Clustered JDBC.
 * Copyright (C) 2002-2005 French National Institute For Research In Computer
 * Science And Control (INRIA).
 * Contact: c-jdbc@objectweb.org
 * 
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation; either version 2.1 of the License, or any later
 * version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
 * for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * Initial developer(s): Nicolas Modrzyk
 * Contributor(s): Emmanuel Cecchet.
 */

package org.objectweb.cjdbc.common.stream;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.InflaterInputStream;

/**
 * This is a useful stream class to compress and decompress object to a stream.
 * 
 * @author <a href="mailto:Nicolas.Modrzyk@inrialpes.fr">Nicolas Modrzyk </a>
 * @author <a href="mailto:Emmanuel.Cecchet@inria.fr">Emmanuel Cecchet </a>
 */
public class CJDBCStream
{
  /** Clean the stream after CLEAN_INTERVAL call to writeUnshared */
  public static final int CLEAN_INTERVAL = 10;

  /** Identifier of an object on the stream */
  public static final int OBJECT         = 0;
  /** Identifier of <code>null</code> on the stream */
  public static final int NULL           = 1;
  /** Identifier of a <code>String</code> object on the stream */
  public static final int STRING_OBJECT  = 2;
  /** Identifier of an <code>Integer</code> object on the stream */
  public static final int INTEGER_OBJECT = 3;
  /** Identifier of a <code>Long</code> object on the stream */
  public static final int LONG_OBJECT    = 4;
  /** Identifier of a <code>Boolean</code> object on the stream */
  public static final int BOOLEAN_OBJECT = 5;

  /**
   * Decompress an object from its byte-compressed form to java object
   * 
   * @param array of bytes
   * @return the object if it can be retrieved
   * @throws IOException if fails to read
   * @throws ClassNotFoundException if class of object does not exist
   */
  public static final Object decompressObject(byte[] array) throws IOException,
      ClassNotFoundException
  {
    ByteArrayInputStream bos = new ByteArrayInputStream(array);
    InflaterInputStream zip = new InflaterInputStream(bos);
    ObjectInputStream oos = new ObjectInputStream(zip);
    Object obj = oos.readObject();
    oos.close();
    bos.close();
    return obj;
  }

  /**
   * Compress an object from its java form to byte array
   * 
   * @param obj to compress
   * @return byte array
   * @throws IOException if fails to read
   */
  public static final byte[] compressObject(Object obj) throws IOException
  {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    DeflaterOutputStream zip = new DeflaterOutputStream(bos, new Deflater(
        Deflater.BEST_COMPRESSION));
    ObjectOutputStream oos = new ObjectOutputStream(zip);
    oos.writeObject(obj);
    oos.flush();
    oos.close();
    bos.close();
    byte[] data = bos.toByteArray();
    return data;
  }

  /**
   * Statistic method to count the number of bytes of a class.
   * 
   * @param obj to count bytes
   * @return the number of bytes
   * @throws IOException if fails to read
   */
  public static final int countBytes(Object obj) throws IOException
  {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream oos = new ObjectOutputStream(bos);
    oos.writeObject(obj);
    oos.flush();
    oos.close();
    bos.close();
    return bos.size();
  }

}

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