propertymanager.java

这是学习Java必须读懂两套源代码

/**
 * Copyright (C) 2001 Yasna.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * 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
 *        Yasna.com (http://www.yasna.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Yazd" and "Yasna.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Yazd",
 *    nor may "Yazd" appear in their name, without prior written
 *    permission of Yasna.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL YASNA.COM OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Yasna.com. For more information
 * on Yasna.com, please see <http://www.yasna.com>.
 */

/**
 * Copyright (C) 2000 CoolServlets.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * 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
 *        CoolServlets.com (http://www.coolservlets.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Jive" and "CoolServlets.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Jive",
 *    nor may "Jive" appear in their name, without prior written
 *    permission of CoolServlets.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL COOLSERVLETS.COM OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of CoolServlets.com. For more information
 * on CoolServlets.com, please see <http://www.coolservlets.com>.
 */

package com.Yasna.forum;

import java.util.*;
import java.io.*;

/**
 * Manages properties for the entire Yazd system. Properties are merely
 * pieces of information that need to be saved in between server restarts. The
 * class also reports the version of Yazd.
 * <p>
 * At the moment, properties are stored in a Java Properties file. In a version
 * of Yazd coming soon, the properties file format will move to XML. XML
 * properties will allow hierarchical property structures which may mean the
 * API of this class will have to change.
 * <p>
 * Yazd properties are only meant to be set and retrevied by core Yazd classes.
 * Therefore, skin writers should probably ignore this class.
 * <p>
 * This class is implemented as a singleton since many classloaders seem to
 * take issue with doing classpath resource loading from a static context.
 */
public class PropertyManager {

    /**
     * The Major version number of Yazd. i.e. 1.x.x
     */
    private static final int MAJOR_VERSION = 1;

    /**
     * The Minor version number of Yazd. i.e. x.1.x.
     */
    private static final int MINOR_VERSION = 0;

    /**
     * The revision version number of Yazd. i.e. x.x.1.
     */
    private static final int REVISION_VERSION = 0;

    private static PropertyManager manager = null;
    private static Object managerLock = new Object();
    private static String propsName = "/yazd.properties";

    /**
     * Returns a Yazd property.
     *
     * @param name the name of the property to return.
     * @return the property value specified by name.
     */
    public static String getProperty(String name) {
        if (manager == null) {
            synchronized(managerLock) {
                if (manager == null) {
                    manager = new PropertyManager(propsName);
                }
            }
        }
        return manager.getProp(name);
    }

    /**
     * Sets a Yazd property. If the property doesn't already exists, a new
     * one will be created.
     *
     * @param name the name of the property being set.
     * @param value the value of the property being set.
     */
    public static void setProperty(String name, String value) {
        if (manager == null) {
            synchronized(managerLock) {
                if (manager == null) {
                    manager = new PropertyManager(propsName);
                }
            }
        }
        manager.setProp(name, value);
    }

    /**
     * Deletes a Yazd property. If the property doesn't exist, the method
     * does nothing.
     *
     * @param name the name of the property to delete.
     */
    public static void deleteProperty(String name) {
        if (manager == null) {
            synchronized(managerLock) {
                if (manager == null) {
                    manager = new PropertyManager(propsName);
                }
            }
        }
        manager.deleteProp(name);
    }

    /**
     * Returns the names of the Yazd properties.
     *
     * @return an Enumeration of the Yazd property names.
     */
    public static Enumeration propertyNames() {
        if (manager == null) {
            synchronized(managerLock) {
                if (manager == null) {
                    manager = new PropertyManager(propsName);
                }
            }
        }
        return manager.propNames();
    }

    /**
     * Returns true if the properties are readable. This method is mainly
     * valuable at setup time to ensure that the properties file is setup
     * correctly.
     */
    public static boolean propertyFileIsReadable() {
        if (manager == null) {
            synchronized(managerLock) {
                if (manager == null) {
                    manager = new PropertyManager(propsName);
                }
            }
        }
        return manager.propFileIsReadable();
    }

    /**
     * Returns true if the properties are writable. This method is mainly
     * valuable at setup time to ensure that the properties file is setup
     * correctly.
     */
    public static boolean propertyFileIsWritable() {