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    • net.sourceforge.squirrel_sql.fw.xml.XMLObjectCache Maven / Gradle / Ivy

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    The framework library contains utility classes that are generic and useful for building applications that introspect a database via JDBC. These are not intended to be SQuirreLSQL-specific and could be used by other projects JDBC front-end applications. This project is guaranteed to have no code dependencies on other SQuirreLSQL projects and could therefore be used when building a different JDBC front-end application.

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    package net.sourceforge.squirrel_sql.fw.xml;
/*
 * Copyright (C) 2001-2003 Colin Bell
 * [email protected]
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.Reader;
import java.util.Iterator;

import net.sourceforge.squirrel_sql.fw.id.IHasIdentifier;
import net.sourceforge.squirrel_sql.fw.id.IIdentifier;
import net.sourceforge.squirrel_sql.fw.util.DuplicateObjectException;
import net.sourceforge.squirrel_sql.fw.util.IObjectCache;
import net.sourceforge.squirrel_sql.fw.util.IObjectCacheChangeListener;
import net.sourceforge.squirrel_sql.fw.util.ObjectCache;
import net.sourceforge.squirrel_sql.fw.util.StringManager;
import net.sourceforge.squirrel_sql.fw.util.StringManagerFactory;
/**
 * This class is a cache of objects that can be read from/written to an XML
 * document. All objects stored must implement IHasIdentifier.
    
 *
 * It is implemented using ObjectCache.
 *
 * @author Colin Bell
 */
public class XMLObjectCache implements IObjectCache
{
	/** Internationalized strings for this class. */
	private static final StringManager s_stringMgr =
		StringManagerFactory.getStringManager(XMLObjectCache.class);

	/** Cache of stored objects. */
	private ObjectCache _cache = new ObjectCache();

	/**
	 * Default ctor.
	 */
	public XMLObjectCache()
	{
		super();
	}

	/**
	 * Retrieve a stored object.
	 *
	 * @param	objClass	The class of the object to be retrieved.
	 * @param	id			The IIdentifier that identifies
	 *						the object to be retrieved.
	 *
	 * @return	The IHasIdentifier retrieved or null
	 *			if no object exists for id.
	 */
	public IHasIdentifier get(Class objClass, IIdentifier id)
	{
		return _cache.get(objClass, id);
	}

	/**
	 * Store an object.
	 *
	 * @param	obj	Object to be stored.
	 *
	 * @exception	DuplicateObjectException
	 *				Thrown if an object of the same class as obj
	 *				and with the same identifier is already in the cache.
	 */
	public void add(E obj) throws DuplicateObjectException
	{
		_cache.add(obj);
	}

	/**
	 * Remove an object.
	 *
	 * @param	objClass	Class of object to be removed.
	 * @param	id			Identifier for object to be removed.
	 */
	public void remove(Class objClass, IIdentifier id)
	{
		_cache.remove(objClass, id);
	}

	/**
	 * Return an array of Class[] getAllClasses()
	{
		return _cache.getAllClasses();
	}

	/**
	 * Return an Iterator of all objects stored for the
	 * passed class.
	 *
	 * @param	objClass	Class to return objects for.
	 *
	 * @return	Iterator over all objects.
	 */
	public Iterator getAllForClass(Class objClass)
	{
		return _cache.getAllForClass(objClass);
	}

	/**
	 * Adds a listener for changes to the cache entry for the passed class.
	 *
	 * @param	lis			an IObjectCacheChangeListener that will be notified
	 *						when objects are added and removed from this cache
	 *						entry.
	 * @param	objClass	The class of objects whose cache we want to listen
	 *						to.
	 */
	public void addChangesListener(IObjectCacheChangeListener lis, Class objClass)
	{
		_cache.addChangesListener(lis, objClass);
	}

	/**
	 * Removes a listener for changes to the cache entry for the passed class.
	 *
	 * @param	lis			an IObjectCacheChangeListener that will be notified
	 *						when objects are added and removed from this cache
	 *						entry.
	 * @param	objClass	The class of objects whose cache we want to listen
	 *						to.
	 */
	public void removeChangesListener(IObjectCacheChangeListener lis,
										Class objClass)
	{
		_cache.removeChangesListener(lis, objClass);
	}

	/**
	 * Load from an XML document.
	 *
	 * @param	xmlFileName	Name of XML file to load from.
	 *
	 * @exception	FileNotFoundException
	 *				Thrown if file not found.
	 *
	 * @exception	XMLException
	 *				Thrown if an XML error occurs.
	 *
	 * @exception	DuplicateObjectException
	 *				Thrown if two objects of the same class
	 *				and with the same identifier are added to the cache.
	 */
	public void load(String xmlFileName)
		throws FileNotFoundException, XMLException, DuplicateObjectException
	{
		load(xmlFileName, null);
	}

	/**
	 * Load from an XML document but don't ignore duplicate objects.
	 *
	 * @param	xmlFileName	Name of XML file to load from.
	 * @param	cl			Class loader to use for object creation.
	 *
	 * @exception	FileNotFoundException
	 *				Thrown if file not found.
	 *
	 * @exception	XMLException
	 *				Thrown if an XML error occurs.
	 *
	 * @exception	DuplicateObjectException
	 *				Thrown if two objects of the same class
	 *				and with the same identifier are added to the cache.
	 */
	public void load(String xmlFileName, ClassLoader cl)
		throws FileNotFoundException, XMLException, DuplicateObjectException
	{
		XMLBeanReader rdr = new XMLBeanReader();
		rdr.load(xmlFileName, cl);
		for (Iterator it = rdr.iterator(); it.hasNext();)
		{
			final Object obj = it.next();
			if (!(obj instanceof IHasIdentifier))
			{
				throw new XMLException(s_stringMgr.getString("XMLObjectCache.error.notimplemented"));
			}
			add((E)obj);
		}
	}

	/**
	 * Load from a reader over an XML document. Use the system classloader and
	 * don't ignore duplicate objects.
	 *
	 * @param	rdr	Reader over the XML document.
	 *
	 * @exception	XMLException
	 *				Thrown if an XML error occurs.
	 *
	 * @exception	DuplicateObjectException
	 *				Thrown if two objects of the same class
	 *				and with the same identifier are added to the cache.
	 */
	public void load(Reader rdr) throws XMLException, DuplicateObjectException
	{
		load(rdr, null, false);
	}

	/**
	 * Load from a reader over an XML document.
	 *
	 * @param	rdr					Reader over the XML document.
	 * @param	cl					Class loader to use for object creation. Pass
	 * 								null to use the system classloader.
	 * @param	ignoreDuplicates	If true don't throw a
	 * 								DuplicateObjectException but rather
	 * 								ignore the attempt to add a duplicate, in
	 *								this case there will be only one object added to
	 *								the cache.
	 *
	 * @exception	XMLException
	 *				Thrown if an XML error occurs.
	 *
	 * @exception	DuplicateObjectException
	 *				Thrown if two objects of the same class
	 *				and with the same identifier are added to the cache.
	 */
	public void load(Reader rdr, ClassLoader cl, boolean ignoreDuplicates)
		throws XMLException, DuplicateObjectException
	{
		XMLBeanReader xmlRdr = new XMLBeanReader();
		xmlRdr.load(rdr, cl);
		for (Iterator it = xmlRdr.iterator(); it.hasNext();)
		{
			final Object obj = it.next();
			if (!(obj instanceof IHasIdentifier))
			{
				throw new XMLException(s_stringMgr.getString("XMLObjectCache.error.notimplemented"));
			}
			try
			{
				add((E) obj);
			}
			catch (DuplicateObjectException ex)
			{
				if (!ignoreDuplicates)
				{
					throw ex;
				}
			}
		}
	}

	/**
	 * Save all objects in this cache to an XML document.
	 *
	 * @param	xmlFileName	 Name of XML file to save to.
	 *
	 * @exception	IOException
	 *				Thrown if an IO error occurs.
	 *
	 * @exception	XMLException
	 *				Thrown if an XML error occurs.
	 */
	public synchronized void save(String xmlFilename)
		throws IOException, XMLException
	{
		XMLBeanWriter wtr = new XMLBeanWriter();
		Class[] classes = _cache.getAllClasses();
		for (int i = 0; i < classes.length; ++i)
		{
			for (Iterator it = _cache.getAllForClass(classes[i]);
					it.hasNext();)
			{
				wtr.addToRoot(it.next());
			}
		}
		wtr.save(xmlFilename);
	}

	/**
	 * Save all objects of type objClass to an XML document.
	 *
	 * @param	xmlFileName	 Name of XML file to save to.
	 * @param	forClass		Class of objects to be saved.
	 *
	 * @exception	IOException
	 *				Thrown if an IO error occurs.
	 *
	 * @exception	XMLException
	 *				Thrown if an XML error occurs.
	 */
	public synchronized void saveAllForClass(String xmlFilename,
	                                         Class forClass)
		throws IOException, XMLException
	{
		XMLBeanWriter wtr = new XMLBeanWriter();
		for (Iterator it = _cache.getAllForClass(forClass); it.hasNext();)
		{
			wtr.addToRoot(it.next());
		}
		wtr.save(xmlFilename);
	}
}
    
    
    
    

    




    
    
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