idtablenodeleaf.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 Library 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: IDTableNodeLeaf.java,v 1.3 2000/11/09 10:51:33 daniela Exp $

package org.ozoneDB.core.wizardStore;

import java.io.*;
import org.ozoneDB.DxLib.*;
import org.ozoneDB.core.ObjectID;


/**
 * This extension of the DxDiskHashNodeLeaf class assumes that the key and data
 * member of the stored DxKayData pairs are ObjectIDs. Thus is casts and writes
 * them directly to the stream for better performance.
 */
class IDTableNodeLeaf extends DxDiskHashNodeLeaf implements Externalizable {
    
    final static long serialVersionUID = 1L;
    
    
    public IDTableNodeLeaf( DxDiskHashMap _grandParent ) {
        super( _grandParent );
    }
    
    
    public void writeExternal( ObjectOutput out ) throws IOException {
        byte c = 0;
        for (DxKeyData elem = element; elem != null; elem = elem.next) {
            c++;
        } 
        out.writeByte( c );
        
        DxKeyData elem = element;
        while (elem != null) {
            ((ObjectID)elem.key).writeExternal( out );
            ((ObjectID)elem.data).writeExternal( out );
            elem = elem.next;
        } 
    } 
    
    
    public void readExternal( ObjectInput in ) throws IOException, ClassNotFoundException {
        byte c = in.readByte();
        
        ObjectID key = ((IDTable)grandParent).newObjectID();
        key.readExternal( in );
        ClusterID data = ((IDTable)grandParent).newClusterID();
        data.readExternal( in );
        element = grandParent.newKeyData();
        element.set( key, data );
        
        DxKeyData elem = element;
        for (int i = 1; i < c; i++) {
            key = ((IDTable)grandParent).newObjectID();
            key.readExternal( in );
            data = ((IDTable)grandParent).newClusterID();
            data.readExternal( in );
            elem.next = ((IDTable)grandParent).newKeyData();
            elem.next.set( key, data );
            elem = elem.next;
        } 
    } 
}