/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2000,2008 Oracle. All rights reserved.
*
* $Id: SerialBinding.java,v 12.9 2008/02/07 17:12:25 mark Exp $
*/
package com.sleepycat.bind.serial;
import java.io.IOException;
import com.sleepycat.bind.EntryBinding;
import com.sleepycat.db.DatabaseEntry;
import com.sleepycat.util.FastInputStream;
import com.sleepycat.util.FastOutputStream;
import com.sleepycat.util.RuntimeExceptionWrapper;
/**
* A concrete EntryBinding
that treats a key or data entry as
* a serialized object.
*
*
This binding stores objects in serialized object format. The
* deserialized objects are returned by the binding, and their
* Class
must implement the Serializable
* interface.
For key bindings, a tuple binding is usually a better choice than a * serial binding. A tuple binding gives a reasonable sort order, and works * with comparators in all cases -- see below.
* *WARNING: SerialBinding should not be used with Berkeley DB Java * Edition for key bindings, when a custom comparator is used. In JE, * comparators are instantiated and called internally at times when databases * are not accessible. Because serial bindings depend on the class catalog * database, a serial binding cannot be used during these times. An attempt * to use a serial binding with a custom comparator will result in a * NullPointerException during environment open or close.
* * @author Mark Hayes */ public class SerialBinding extends SerialBase implements EntryBinding { private ClassCatalog classCatalog; private Class baseClass; /** * Creates a serial binding. * * @param classCatalog is the catalog to hold shared class information and * for a database should be a {@link StoredClassCatalog}. * * @param baseClass is the base class for serialized objects stored using * this binding -- all objects using this binding must be an instance of * this class. */ public SerialBinding(ClassCatalog classCatalog, Class baseClass) { if (classCatalog == null) { throw new NullPointerException("classCatalog must be non-null"); } this.classCatalog = classCatalog; this.baseClass = baseClass; } /** * Returns the base class for this binding. * * @return the base class for this binding. */ public final Class getBaseClass() { return baseClass; } /** * Returns the class loader to be used during deserialization, or null if * a default class loader should be used. The default implementation of * this method returns *Thread.currentThread().getContextClassLoader()
to use the
* context class loader for the current thread.
*
* This method may be overridden to return a dynamically determined class
* loader. For example, getBaseClass().getClassLoader()
could
* be called to use the class loader for the base class, assuming that a
* base class has been specified.
If this method returns null, a default class loader will be used as
* determined by the java.io.ObjectInputStream.resolveClass
* method.
Note that this method sets the DatabaseEntry offset property to a * non-zero value and the size property to a value less than the length of * the byte array.
* * @param object is the input deserialized object. * * @param entry is the output serialized entry. * * @throws IllegalArgumentException if the object is not an instance of the * base class for this binding. */ public void objectToEntry(Object object, DatabaseEntry entry) { if (baseClass != null && !baseClass.isInstance(object)) { throw new IllegalArgumentException( "Data object class (" + object.getClass() + ") not an instance of binding's base class (" + baseClass + ')'); } FastOutputStream fo = getSerialOutput(object); try { SerialOutput jos = new SerialOutput(fo, classCatalog); jos.writeObject(object); } catch (IOException e) { throw new RuntimeExceptionWrapper(e); } byte[] hdr = SerialOutput.getStreamHeader(); entry.setData(fo.getBufferBytes(), hdr.length, fo.getBufferLength() - hdr.length); } }