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/* MarshalledObject.java --

   Copyright (c) 1996, 1997, 1998, 1999, 2004, 2006

   Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath 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

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package java.rmi;

import gnu.java.rmi.RMIMarshalledObjectInputStream;

import gnu.java.rmi.RMIMarshalledObjectOutputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.Serializable;

/**

 * A <code>MarshalledObject</code> consists of a serialized object which is

 * marshalled according to the RMI specification.

 * <p>

 * An object passed to the constructor is serialized and tagged with the needed

 * URL to retrieve its class definition for remote usage. If the object is a

 * remote reference its stub is serialized instead. The instance of this

 * marshalled object can be later retrieved by its <code>get()</code> method.

 * </p>

 *

 * @author unknown

 */

public final class MarshalledObject<T>

  implements Serializable

{

  // The following fields are from Java API Documentation "Serialized form"

  private static final long serialVersionUID = 8988374069173025854L;

  byte[] objBytes;

  byte[] locBytes;

  int hash;

  /**

   * Constructs a <code>MarshalledObject</code> from the given object.

   *

   * @param obj the object to marshal

   * @throws IOException if an I/O error during serialization occurs.

   */

  public MarshalledObject(T obj) throws IOException

  {

    ByteArrayOutputStream objStream = new ByteArrayOutputStream();

    RMIMarshalledObjectOutputStream stream =

      new RMIMarshalledObjectOutputStream(objStream);

    stream.writeObject(obj);

    stream.flush();

    objBytes = objStream.toByteArray();

    locBytes = stream.getLocBytes();

    // The following algorithm of calculating hashCode is similar to String

    hash = 0;

    for (int i = 0; i < objBytes.length; i++)

      hash = hash * 31 + objBytes[i];

    if (locBytes != null)

      for (int i = 0; i < locBytes.length; i++)

        hash = hash * 31 + locBytes[i];

  }

  /**

   * Checks if the given object is equal to this marshalled object.

   *

   * <p>Marshalled objects are considered equal if they contain the

   * same serialized object. Codebase annotations where the class

   * definition can be downloaded are ignored in the equals test.</p>

   *

   * @param obj the object to compare.

   * @return <code>true</code> if equal, <code>false</code> otherwise.

   */

  public boolean equals(Object obj)

  {

    if (! (obj instanceof MarshalledObject))

      return false;

    // hashCode even differs, don't do the time-consuming comparisons

    if (obj.hashCode() != hash)

      return false;

    MarshalledObject aobj = (MarshalledObject) obj;

    if (objBytes == null || aobj.objBytes == null)

      return objBytes == aobj.objBytes;

    if (objBytes.length != aobj.objBytes.length)

      return false;

    for (int i = 0; i < objBytes.length; i++)

      {

        if (objBytes[i] != aobj.objBytes[i])

          return false;

      }

    // Ignore comparison of locBytes(annotation)

    return true;

  }

  /**

   * Constructs and returns a copy of the internal serialized object.

   *

   * @return The deserialized object.

   *

   * @throws IOException if an I/O exception occurs during deserialization.

   * @throws ClassNotFoundException if the class of the deserialized object

   * cannot be found.

   */

  public T get() throws IOException, ClassNotFoundException

  {

    if (objBytes == null)

      return null;

    RMIMarshalledObjectInputStream stream =

      new RMIMarshalledObjectInputStream(objBytes, locBytes);

    return (T) stream.readObject();

  }

  public int hashCode()

  {

    return hash;

  }

}