donaldp 2002/11/10 01:29:57
Added: fortress/src/java/org/apache/excalibur/fortress/util
OverridableServiceManager.java
Log:
Add an OveridableServiceManager compliment to OveridableContext
Revision Changes Path
1.1
jakarta-avalon-excalibur/fortress/src/java/org/apache/excalibur/fortress/util/OverridableServiceManager.java
Index: OverridableServiceManager.java
===================================================================
/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE.txt file.
*/
package org.apache.excalibur.fortress.util;
import org.apache.avalon.framework.service.DefaultServiceManager;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.ServiceException;
/**
* The OverridableServiceManager allows you to "null" out entries, even if they are
* in a parent {@link org.apache.avalon.framework.service.ServiceManager}.
*
* @author <a href="mailto:peter at apache.org">Peter Donald</a>
* @version $Revision: 1.1 $ $Date: 2002/11/10 09:29:57 $
*/
public class OverridableServiceManager
extends DefaultServiceManager
{
/**
* Marker object that indicates something has bene deliberately nulled out.
*/
private static final Object MARKER = new Object();
/**
* Create a OverridableServiceManager with specified parent.
*
* @param parent the parent ServiceManager
*/
public OverridableServiceManager( final ServiceManager parent )
{
super( parent );
}
/**
* Lookup service and if the marker is found then
* assume that null has been added and thus throw a ServiceException.
*
* @param key the key to lookup
* @return the service instance
* @throws ServiceException
*/
public Object lookup( final String key )
throws ServiceException
{
final Object object = super.lookup( key );
if( MARKER == object )
{
throw new ServiceException( key, "Unable to locate service" );
}
return object;
}
/**
* Put a service into ServiceManager. If null service is added
* then a marker is instead placed into map (thus hiding potential
* service in parent serviceManager).
*
* @param key the key
* @param object the service
*/
public void put( final String key, final Object object )
{
if( null == object )
{
super.put( key, MARKER );
}
else
{
super.put( key, object );
}
}
}
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