objectid.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: ObjectID.java,v 1.4 2002/08/27 08:32:25 per_nyfelt Exp $

package org.ozoneDB.core;

import java.io.*;

import org.ozoneDB.DxLib.DxCompatible;
import org.ozoneDB.DxLib.DxObject;


public class ObjectID extends DxObject implements Externalizable,Comparable {

    final static long serialVersionUID = 2;
    final static byte subSerialVersionUID = 1;

    private long value = -1;


    public ObjectID() {
    }

    /**
     * Constructor from a string representation aka a handle.
     *
     */
    public ObjectID(String handle) {
        value = Long.parseLong(handle);
    }

    public ObjectID(long v) {
        value = v;
    }

    public final long value() {
        return value;
    }


    public final int hashCode() {
        //wenn diese 32 bits keinen unterschied mehr bringen,
        //wird mit equals() weiter verglichen
        return (int) value;
    }


    public final boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj != null && obj instanceof ObjectID) {
            return value == ((ObjectID) obj).value;
        }
        return false;
    }


    public final boolean isLess(DxCompatible obj) {
        if (obj instanceof ObjectID) {
            return value < ((ObjectID) obj).value;
        }
        return false;
    }


    public int compareTo(Object o) {
        return compareTo((ObjectID) o);
    }

    /**
        Compares this ObjectID to the given ObjectID. This is useful for ozone objects which
        need a sort order but may not be equals. (E.g. for use in a {@link java.util.SortedSet}.)

        @return
            !=0 for ObjectIDs which are not equal
            0 for ObjectIDs which are equal
    */
    public int comparTo(ObjectID o) {
        long diff = value()-o.value();

        return diff>0?1:diff<0?-1:0;
    }

    public Object clone() {
        return new ObjectID(value);
    }


    public final void writeExternal(ObjectOutput out) throws IOException {
        // env.logWriter.newEntry ("write: " + getClass().toString() + " " + value, LogWriter.DEBUG);
        out.writeByte(subSerialVersionUID);
        out.writeLong(value);
    }


    public final void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        byte streamVersionUID = in.readByte();
        value = in.readLong();
        // env.logWriter.newEntry ("read: " + getClass().toString() + " " + value, LogWriter.DEBUG);
    }


    /**
     * The value of the ObjectID as String. Do not change this, the name
     * of the cluster files depend on it.
     */
    public String toString() {
        return String.valueOf(value);
    }
}