jahiapagecache.java

java 写的一个新闻发布系统

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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.JahiaPageInfo;


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


    //-------------------------------------------------------------------------
    /**
     * constructor
     */
    private JahiaPageCache ()
    {
        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 JahiaPageCache getInstance()
    {
        if (mObject == null) {
            mObject = new JahiaPageCache();
        }
        return mObject;
    }

    //-------------------------------------------------------------------------
    /**
     * adds a page to the registry
     *
     * @param        thePage             the JahiaPage object to add
     */
    public synchronized void add (JahiaPageInfo thePage)
    {
        mCache.put (new Integer (thePage.getID()), thePage);
    }


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


    //-------------------------------------------------------------------------
    /**
     * 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 JahiaPageInfo lookup (int pageID)
    {
        return (JahiaPageInfo) mCache.get (new Integer (pageID));
    }


    //-------------------------------------------------------------------------
    /**
     * 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 getAllPageIDs ()
    {
        return mCache.keys();
    }

}