dblocalclient.java

用Java写的面相对象的数据库管理系统

// 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) 1997-2000 by SMB GmbH. All rights reserved.
//
// $Id: DbLocalClient.java,v 1.9 2000/11/02 20:00:25 daniela Exp $

package org.ozoneDB.core.DbRemote;

import java.io.*;
import org.ozoneDB.DxLib.*;
import org.ozoneDB.DxLib.net.DxClient;
import org.ozoneDB.*;
import org.ozoneDB.core.*;
import org.ozoneDB.util.*;


/**
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.9 $Date: 2000/11/02 20:00:25 $
 */
public class DbLocalClient extends DbClient {
    
    protected Env env;
    
    protected User user;
    
    protected DbCommand currentCommand = null;
    
    protected ByteArrayOutputStream copyStream;
    
    
    public DbLocalClient( ExternalDatabase _db, Env _env, String _user ) throws Exception{
        super( _db, _user );
        env = _env;
        
        user = env.userManager.userForName( _user );
        if (user == null) {
            throw new PermissionDeniedExc( "No such user." );
        } 
        
        copyStream = new ByteArrayOutputStream( 4 * 1024 );
    }
    
    
    public synchronized void send( Object obj ) throws IOException {
        try {
            copyStream.reset();
            
            // FIXME: copy only args of DbInvoke
            currentCommand = (DbCommand)copyObject( obj, false );
            currentCommand.env = env;
            env.transactionManager.handleCommand( currentCommand, user );
        } catch (Exception e) {
            throw new IOException( e.toString() );
        } 
    } 
    
    
    public synchronized Object receive() throws IOException, ClassNotFoundException {
        return copyObject( currentCommand.result, true );
    } 
    
    
    /**
     * Copy the given object using ByteArrayStreams so all streamable
     * objects (all database objects) can be copied.
     */
    protected synchronized Object copyObject( Object obj, boolean updateLinks ) throws IOException {
        ObjectInputStream in = null;
        try {
            copyStream.reset();
            
            ObjectOutputStream out = new ObjectOutputStream( copyStream );
            out.writeObject( obj );
            out.close();
            
            in = new ObjectInputStream( new ByteArrayInputStream( copyStream.toByteArray() ) );
            
            // remove in finally clause
            if (updateLinks) {
                OzoneProxy.linkTable.addForKey( db, in );
            } 
            
            Object result = in.readObject();
            
            return result;
        } catch (Exception e) {
            throw new IOException( e.toString() );
        } finally {
            if (updateLinks && in != null) {
                OzoneProxy.linkTable.removeForKey( in );
            } 
        } 
    
    } 
    
    
    public boolean objectAvailable() {
        throw new RuntimeException( "Method not implemented." );
    } 
    
    
    public synchronized void close() throws IOException {
    } 
    
    
    public void onConnect() throws IOException {
        throw new RuntimeException( "Method not implemented." );
    } 
    
    
    public void onDeconnect() throws IOException {
        throw new RuntimeException( "Method not implemented." );
    } 
    
    
    public ObjectInputStream inputStream() {
        throw new RuntimeException( "Method not implemented." );
    } 
    
    
    public ObjectOutputStream outputStream() {
        throw new RuntimeException( "Method not implemented." );
    } 
    
}