classmanager.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: ClassManager.java,v 1.8 2002/12/29 11:15:56 per_nyfelt Exp $

package org.ozoneDB.core;

import org.ozoneDB.OzoneClassNotFoundException;
import org.ozoneDB.util.LogWriter;


/**
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.8 $Date: 2002/12/29 11:15:56 $
 */
public final class ClassManager extends ServerComponent {

    protected ClassLoader classLoader;


    public ClassManager( Env _env ) {
        super( _env );
    }


    public void startup() throws Exception {
        env.logWriter.newEntry( this, "startup...", LogWriter.INFO );
        dropClasses();
    }


    public void shutdown() throws Exception {
        env.logWriter.newEntry( this, "shutdown...", LogWriter.INFO );
    }


    public void save() throws Exception {
    }


    public Class classForName( String name ) throws OzoneClassNotFoundException {
        if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
            env.logWriter.newEntry( this, "classForName(): " + name, LogWriter.DEBUG3 );
        }
        try {
            // TODO: remove this if the classLoader works
            // as long as the OzoneClassLoader does not work as expected and does
            // not allow to drop classes we can directly use the context loader
            // of the thread to avoid problems in managed environments like
            // servlets
            //Class cl;
            // If we do not use OzoneClassLoader, we have to care for primitive types ourselves
            //cl = OzoneClassLoader.primitiveType(name);
            //if (cl==null) {
            //    cl = Thread.currentThread().getContextClassLoader().loadClass( name );
            //}

           Class cl = classLoader.loadClass( name );

            if (env.logWriter.hasTarget( LogWriter.DEBUG3 )) {
                env.logWriter.newEntry( this, "    class: " + cl.getName() + ", " + cl.hashCode(), LogWriter.DEBUG3 );
            }
            return cl;
        }
        catch (ClassNotFoundException e) {
            throw new OzoneClassNotFoundException( e.getMessage() );
        }
    }


    public void dropClasses() throws Exception {
        env.logWriter.newEntry( this, "dropClasses()", LogWriter.DEBUG3 );
        classLoader = new OzoneClassLoader();
    }
}