jahiapagetemplatecache.java

java 写的一个新闻发布系统

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//    _______|  /--|    |    |    -   \  _    |    :    -   \_________
//   \\______: :---|    :    :           |    :    |         \________>
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//                 . . . i n   j a h i a   w e   t r u s t . . .
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package org.jahia.services.pages;

import java.util.Hashtable;
import java.util.Enumeration;
import org.jahia.services.pages.JahiaPageDefinition;


/**
 * This class is used by the JahiaPageBaseService class. It implements cache
 * storing page infos.
 *
 * @author  Fulco Houkes
 * @version 1.0
 */
class JahiaPageTemplateCache
{
    private static  JahiaPageTemplateCache mObject = null;
    private static Hashtable mCache = null;


    //-------------------------------------------------------------------------
    /**
     * constructor
     */
    private JahiaPageTemplateCache ()
    {
        mCache = new Hashtable ();
    }

    //-------------------------------------------------------------------------
    /**
     * Reset the cache, by removing all the pages from the cache
     */
    public synchronized void reset ()
    {
        mCache.clear();
    }


    //-------------------------------------------------------------------------
    /**
     * returns an instance of the registry
     */
    public static synchronized JahiaPageTemplateCache getInstance()
    {
        if (mObject == null) {
            mObject = new JahiaPageTemplateCache();
        }
        return mObject;
    }

    //-------------------------------------------------------------------------
    /**
     * adds a page to the registry
     *
     * @param        thePage             the JahiaPage object to add
     *
     */
    public synchronized void add (JahiaPageDefinition template)
    {
        mCache.put (new Integer (template.getID()), template);
        JahiaPageDefinition pageDef = (JahiaPageDefinition)mCache.get(new Integer(template.getID()));
        //System.out.println(" added template in cache " + pageDef.getName() );
    }


    //-------------------------------------------------------------------------
    /**
     * removes a page from the registry
     *
     * @param        pageID              the page id to be removed
     *
     */
    public synchronized void remove (int templateID)
    {
        mCache.remove (new Integer (templateID));
    }


    //-------------------------------------------------------------------------
    /**
     * Return the page related to the specified ID. If the page is not present
     * in the registry, an attempt is made to extract if from the database
     *
     * @param        pageID              the page id
     * @return       a JahiaPage object
     *
     */
    public JahiaPageDefinition get (int templateID)
    {
        return (JahiaPageDefinition) mCache.get (new Integer (templateID));
    }


    //-------------------------------------------------------------------------
    /**
     * Return the internal state of the cache
     *
     * @return  Return a string containing all the pages ID present in the
     *          cache.
     */
    public String toString ()
    {
        return "<not yet implemented .. any volunteer ?";
    }

    //-------------------------------------------------------------------------
    /**
     * Return all the page IDs present in the cache.
     *
     * @return  Return an enumeration holding all the page IDs present in the
     *          cache.
     */
    public Enumeration getTemplateIDs ()
    {
        return mCache.keys();
    }

    //-------------------------------------------------------------------------
    /** Return all the pages templates present in the cache.
     *
     * @return  Return an Enumeration holding all the page templates.
     */
    public Enumeration getTemplates ()
    {
        return mCache.elements();
    }

}