abstractbasemanager.java

torque服务器源代码

package org.apache.torque.manager;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001-2003 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
 *    derived from this software without prior written permission. For
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 * 5. Products derived from this software may not be called "Apache",
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * information on the Apache Software Foundation, please see
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import java.lang.ref.WeakReference;
import java.util.Arrays;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
import java.util.Iterator;
import java.io.Serializable;
import java.io.IOException;
import java.io.ObjectInputStream;

import org.apache.commons.collections.FastArrayList;
import org.apache.jcs.JCS;
import org.apache.jcs.access.GroupCacheAccess;
import org.apache.jcs.access.exception.CacheException;

import org.apache.torque.Torque;
import org.apache.torque.TorqueException;
import org.apache.torque.om.ObjectKey;
import org.apache.torque.om.Persistent;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * This class contains common functionality of a Manager for
 * instantiating OM's.
 *
 * @author <a href="mailto:[e-mail]">John McNally</a>
 * @version $Id: AbstractBaseManager.java,v 1.16 2003/06/20 08:13:47 dlr Exp $
 */
public abstract class AbstractBaseManager
    implements Serializable
{
    /** the log */
    protected static Log log = LogFactory.getLog(AbstractBaseManager.class);

    /** used to cache the om objects. cache is set by the region property */
    protected transient GroupCacheAccess cache;

    /** method results cache */
    protected MethodResultCache mrCache;

    /** the class that the service will instantiate */
    private Class omClass;

    private String className;

    private String region;

    private boolean isNew = true;

    protected Map validFields;
    protected Map listenersMap = new HashMap();

    /**
     * Get the Class instance
     *
     * @return the om class
     */
    protected Class getOMClass()
    {
        return omClass;
    }

    /**
     * Set the Class that will be instantiated by this manager
     *
     * @param omClass the om class
     */
    protected void setOMClass(Class omClass)
    {
        this.omClass = omClass;
    }

    /**
     * Get a fresh instance of an om
     *
     * @return an instance of the om class
     * @throws InstantiationException
     * @throws IllegalAccessException
     */
    protected Persistent getOMInstance()
        throws InstantiationException, IllegalAccessException
    {
        return (Persistent) omClass.newInstance();
    }

    /**
     * Get the classname to instantiate for getInstance()
     * @return value of className.
     */
    public String getClassName()
    {
        return className;
    }

    /**
     * Set the classname to instantiate for getInstance()
     * @param v  Value to assign to className.
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    public void setClassName(String  v)
        throws TorqueException
    {
        this.className = v;

        try
        {
            setOMClass(Class.forName(getClassName()));
        }
        catch (ClassNotFoundException cnfe)
        {
            throw new TorqueException("Could not load " + getClassName());
        }
    }


    /**
     * Return an instance of an om based on the id
     *
     * @param id
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    protected Persistent getOMInstance(ObjectKey id)
        throws TorqueException
    {
        return getOMInstance(id, true);
    }

    /**
     * Return an instance of an om based on the id
     *
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    protected Persistent getOMInstance(ObjectKey key, boolean fromCache)
        throws TorqueException
    {
        Persistent om = null;
        if (fromCache)
        {
            om = cacheGet(key);
        }

        if (om == null)
        {
            om = retrieveStoredOM(key);
            if (fromCache)
            {
                putInstanceImpl(om);
            }
        }

        return om;
    }

    protected Persistent cacheGet(Serializable key)
    {
        Persistent om = null;
        if (cache != null)
        {
            synchronized (this)
            {
                om = (Persistent) cache.get(key);
            }
        }
        return om;
    }

    /**
     * 
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    protected void clearImpl()
        throws TorqueException
    {
        if (cache != null)
        {
            try
            {
                cache.remove();
            }
            catch (CacheException ce)
            {
                throw new TorqueException(
                        "Could not clear cache due to internal JCS error.", ce);
            }
        }
    }

    /**
     * 
     * @param key
     * @return
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    protected Persistent removeInstanceImpl(Serializable key)
        throws TorqueException
    {
        Persistent oldOm = null;
        if (cache != null)
        {
            try
            {
                synchronized (this)
                {
                    oldOm = (Persistent) cache.get(key);
                    cache.remove(key);
                }
            }
            catch (CacheException ce)
            {
                throw new TorqueException
                    ("Could not remove from cache due to internal JCS error",
                     ce);
            }
        }
        return oldOm;
    }

    /**
     * 
     * @param om
     * @return
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    protected Persistent putInstanceImpl(Persistent om)
        throws TorqueException
    {
        ObjectKey key = om.getPrimaryKey();
        return putInstanceImpl(key, om);
    }

    /**
     * 
     * @param key
     * @param om
     * @return
     * @throws TorqueException Any exceptions caught during processing will be
     *         rethrown wrapped into a TorqueException.
     */
    protected Persistent putInstanceImpl(Serializable key, Persistent om)
        throws TorqueException
    {
        if (getOMClass() != null && !getOMClass().isInstance(om))
        {
            throw new TorqueException(om + "; class=" + om.getClass().getName()
                + "; id=" + om.getPrimaryKey() + " cannot be cached with "
                + getOMClass().getName() + " objects");
        }

        Persistent oldOm = null;
        if (cache != null)
        {
            try
            {
                synchronized (this)
                {
                    oldOm = (Persistent) cache.get(key);
                    cache.put(key, om);
                }
            }
            catch (CacheException ce)
            {
                throw new TorqueException
                    ("Could not cache due to internal JCS error", ce);
            }
        }
        return oldOm;
    }