stringkey.java

torque服务器源代码

package org.apache.torque.om;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Turbine" must not be used to endorse or promote products
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 * 5. Products derived from this software may not be called "Apache",
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */


/**
 * This class can be used as an ObjectKey to uniquely identify an
 * object within an application where the id  consists
 * of a single entity such a GUID or the value of a db row's primary key.
 *
 * @author <a href="mailto:[e-mail]">John McNally</a>
 * @version $Id: StringKey.java,v 1.7 2002/11/26 22:32:55 mpoeschl Exp $
 */
public class StringKey extends SimpleKey
{
    /**
     * Creates an SimpleKey whose internal representation will be
     * set later, through a set method
     */
    public StringKey()
    {
    }

    /**
     * Creates a StringKey whose internal representation is a String
     *
     * @param key the key value
     */
    public StringKey(String key)
    {
        this.key = key;
    }

    /**
     * Creates a StringKey that is equivalent to key.
     *
     * @param key the key value
     */
    public StringKey(StringKey key)
    {
        if (key != null)
        {
            this.key = key.getValue();
        }
        else
        {
            this.key = null;
        }
    }

    /**
     * Sets the internal representation to a String
     *
     * @param key the key value
     */
    public void setValue(String key)
    {
        this.key = key;
    }

    /**
     * Sets the internal representation to the same object used by key.
     *
     * @param key the key value
     */
    public void setValue(StringKey key)
    {
        if (key != null)
        {
            this.key = key.getValue();
        }
        else
        {
            this.key = null;
        }
    }

    /**
     * Access the underlying String object.
     *
     * @return a <code>String</code> value
     */
    public String getString()
    {
        return (String) key;
    }

    /**
     * keyObj is equal to this StringKey if keyObj is a StringKey or String
     * that contains the same information this key contains.  Two ObjectKeys
     * that both contain null values are not considered equal.
     *
     * @param keyObj the comparison value
     * @return whether the two objects are equal
     */
    public boolean equals(Object keyObj)
    {
        boolean isEqual = false;

        if (key != null)
        {
            if (keyObj instanceof String)
            {
                isEqual = keyObj.equals(key);
            }
            // check against a StringKey. Two keys are equal, if their
            // internal keys equivalent.
            else if (keyObj instanceof StringKey)
            {
                Object obj = ((StringKey) keyObj).getValue();
                isEqual =  key.equals(obj);
            }
        }
        return isEqual;
    }

    /**
     * get a String representation
     *
     * @return a String representation of an empty String if the value is null
     */
    public String toString()
    {
        if (key != null)
        {
            return (String) key;
        }
        return "";
    }
}