dbxmlforobj.java

Java的面向对象数据库系统的源代码

// You can redistribute this software and/or modify it under the terms of
// the Ozone Core License version 1 published by ozone-db.org.
//
// The original code and portions created by SMB are
// Copyright (C) 1997-@year@ by SMB GmbH. All rights reserved.
//
// $Id: DbXMLForObj.java,v 1.5 2002/12/29 11:15:56 per_nyfelt Exp $

package org.ozoneDB.core.DbRemote;

import org.ozoneDB.OzoneCompatible;
import org.ozoneDB.OzoneProxy;
import org.ozoneDB.core.*;
import org.ozoneDB.core.xml.Object2XML;
import org.ozoneDB.xml.util.*;

import java.io.*;


/**
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.5 $Date: 2002/12/29 11:15:56 $
 */
public final class DbXMLForObj extends DbCommand {

    private OzoneProxy obj;


    public DbXMLForObj() {
    }


    public DbXMLForObj( OzoneProxy _obj ) {
        obj = _obj;
    }


    public void perform( Transaction ta ) throws Exception {
        // env.logWriter.newEntry (this, "DbXMLForObj.perform()...", LogWriter.DEBUG);

        ObjectContainer container = ta.acquireObject( obj.remoteID(), Lock.LEVEL_READ );

        try {
        // cache already converted XML in the container?
        result = createChunk( container );
	    } finally {
	    	container.unpin();
	    }
    }


    public byte[] createChunk( ObjectContainer container ) throws Exception {
        // because of the global locks this statement is not stricktly needed
        synchronized (container) {
            OzoneCompatible target = container.target();

            SAXChunkProducer chunkProducer = new SAXChunkProducer( (SAXChunkProducerDelegate)null );
            chunkProducer.startDocument();

            // check if target provides custom implementation...
            boolean custom = target.toXML( chunkProducer );

            // ...use default mapping otherwise
            if (!custom) {
                Object2XML o2x = new Object2XML( chunkProducer, true );
                o2x.toXML( target );
            }

            chunkProducer.endDocument();

            ChunkOutputStream cos = chunkProducer.chunkStream();
            return cos.toByteArray();
        }
    }


    public void writeExternal( ObjectOutput out ) throws IOException {
        out.writeObject( obj );
    }


    public void readExternal( ObjectInput in ) throws IOException, ClassNotFoundException {
        obj = (OzoneProxy)in.readObject();
    }


    public String toString() {
        return super.toString();
    }

}