/* ====================================================================
 * The Apache Software License, Version 1.1
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 * reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
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 * <http://www.apache.org/>.
 */
package net.sf.hibernate.util;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;

import net.sf.hibernate.type.SerializationException;

/**
 * <p>Assists with the serialization process and performs additional functionality based 
 * on serialization.</p>
 * <p>
 * <ul>
 * <li>Deep clone using serialization
 * <li>Serialize managing finally and IOException
 * <li>Deserialize managing finally and IOException
 * </ul>
 *
 * <p>This class throws exceptions for invalid <code>null</code> inputs.
 * Each method documents its behaviour in more detail.</p>
 *
 * @author <a href="mailto:nissim@nksystems.com">Nissim Karpenstein</a>
 * @author <a href="mailto:janekdb@yahoo.co.uk">Janek Bogucki</a>
 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
 * @author Stephen Colebourne
 * @author Jeff Varszegi
 * @author Gary Gregory
 * @since 1.0
 * @version $Id: SerializationHelper.java,v 1.7 2004/08/02 19:53:50 turin42 Exp $
 */
public final class SerializationHelper {

    private SerializationHelper() {}

    // Clone
    //-----------------------------------------------------------------------
    /**
     * <p>Deep clone an <code>Object</code> using serialization.</p>
     *
     * <p>This is many times slower than writing clone methods by hand
     * on all objects in your object graph. However, for complex object
     * graphs, or for those that don't support deep cloning this can
     * be a simple alternative implementation. Of course all the objects
     * must be <code>Serializable</code>.</p>
     * 
     * @param object  the <code>Serializable</code> object to clone
     * @return the cloned object
     * @throws SerializationException (runtime) if the serialization fails
     */
    public static Object clone(Serializable object) throws SerializationException {
        return deserialize( serialize(object) );
    }
    
    // Serialize
    //-----------------------------------------------------------------------
    /**
     * <p>Serializes an <code>Object</code> to the specified stream.</p>
     *
     * <p>The stream will be closed once the object is written.
     * This avoids the need for a finally clause, and maybe also exception
     * handling, in the application code.</p>
     * 
     * <p>The stream passed in is not buffered internally within this method.
     * This is the responsibility of your application if desired.</p>
     *
     * @param obj  the object to serialize to bytes, may be null
     * @param outputStream  the stream to write to, must not be null
     * @throws IllegalArgumentException if <code>outputStream</code> is <code>null</code>
     * @throws SerializationException (runtime) if the serialization fails
     */
    public static void serialize(Serializable obj, OutputStream outputStream) throws SerializationException {
        if (outputStream == null) {
            throw new IllegalArgumentException("The OutputStream must not be null");
        }
        ObjectOutputStream out = null;
        try {
            // stream closed in the finally
            out = new ObjectOutputStream(outputStream);
            out.writeObject(obj);
            
        } 
        catch (IOException ex) {
            throw new SerializationException("could not serialize object: " + obj, ex);
        } 
        finally {
            try {
                if (out != null) out.close();
            } 
            catch (IOException ignored) {}
        }
    }

    /**
     * <p>Serializes an <code>Object</code> to a byte array for
     * storage/serialization.</p>
     *
     * @param obj  the object to serialize to bytes
     * @return a byte[] with the converted Serializable
     * @throws SerializationException (runtime) if the serialization fails
     */
    public static byte[] serialize(Serializable obj) throws SerializationException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
        serialize(obj, baos);
        return baos.toByteArray();
    }

    // Deserialize
    //-----------------------------------------------------------------------
    /**
     * <p>Deserializes an <code>Object</code> from the specified stream.</p>
     *
     * <p>The stream will be closed once the object is written. This
     * avoids the need for a finally clause, and maybe also exception
     * handling, in the application code.</p>
     * 
     * <p>The stream passed in is not buffered internally within this method.
     * This is the responsibility of your application if desired.</p>
     *
     * @param inputStream  the serialized object input stream, must not be null
     * @return the deserialized object
     * @throws IllegalArgumentException if <code>inputStream</code> is <code>null</code>
     * @throws SerializationException (runtime) if the serialization fails
     */
    public static Object deserialize(InputStream inputStream) throws SerializationException {
        if (inputStream == null) {
            throw new IllegalArgumentException("The InputStream must not be null");
        }
        ObjectInputStream in = null;
        try {
            // stream closed in the finally
            in = new ObjectInputStream(inputStream);
            return in.readObject();
            
        } 
        catch (ClassNotFoundException ex) {
            throw new SerializationException("could not deserialize", ex);
        } 
        catch (IOException ex) {
            throw new SerializationException("could not deserialize", ex);
        } 
        finally {
            try {
                if (in != null) in.close();
            } 
            catch (IOException ex) {}
        }
    }

    /**
     * <p>Deserializes a single <code>Object</code> from an array of bytes.</p>
     *
     * @param objectData  the serialized object, must not be null
     * @return the deserialized object
     * @throws IllegalArgumentException if <code>objectData</code> is <code>null</code>
     * @throws SerializationException (runtime) if the serialization fails
     */
    public static Object deserialize(byte[] objectData) throws SerializationException {
        if (objectData == null) {
            throw new IllegalArgumentException("The byte[] must not be null");
        }
        ByteArrayInputStream bais = new ByteArrayInputStream(objectData);
        return deserialize(bais);
    }
    
}
