Package org.codehaus.loom.components.application

Source Code of org.codehaus.loom.components.application.BlockEntry

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*
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* 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
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*    the documentation and/or other materials provided with the
*    distribution.
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*    products derived from this software without specific prior
*    written permission.
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* ====================================================================
*
* Loom includes code from the Apache Software Foundation
*
* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 1997-2003 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 "Jakarta", "Avalon", and "Apache Software Foundation"
*    must not be used to endorse or promote products derived from this
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* 5. Products derived from this software may not be called "Apache",
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
package org.codehaus.loom.components.application;

import org.codehaus.loom.components.util.info.ComponentInfo;
import org.codehaus.loom.components.util.info.ServiceDescriptor;
import org.codehaus.loom.components.util.metadata.ComponentTemplate;
import org.codehaus.loom.components.util.profile.ComponentProfile;

/**
* This is the structure describing each block before it is loaded.
*
* @author Peter Donald
*/
class BlockEntry
{
    private static final Class BLOCK_CLASS = getBlockClass();

    private Object m_object;
    private final ComponentProfile m_componentProfile;
    private BlockInvocationHandler m_invocationHandler;

    public BlockEntry( final ComponentProfile componentProfile )
    {
        invalidate();
        m_componentProfile = componentProfile;
    }

    public ComponentInfo getInfo()
    {
        return m_componentProfile.getInfo();
    }

    public ComponentTemplate getTemplate()
    {
        return m_componentProfile.getTemplate();
    }

    public String getName()
    {
        return m_componentProfile.getTemplate().getName();
    }

    public synchronized Object getObject()
    {
        return m_object;
    }

    public synchronized void setObject( final Object object )
    {
        invalidate();

        if( null != object &&
            !m_componentProfile.getTemplate().isDisableProxy() )
        {
            final ComponentInfo blockInfo = m_componentProfile.getInfo();
            final Class[] interfaces = getServiceClasses( object,
                                                          blockInfo.getServices() );
            m_invocationHandler =
            new BlockInvocationHandler( object, interfaces );
        }
        m_object = object;
    }

    public synchronized Object getProxy()
    {
        if( m_componentProfile.getTemplate().isDisableProxy() )
        {
            return m_object;
        }
        else
        {
            if( null != m_invocationHandler )
            {
                return m_invocationHandler.getProxy();
            }
            else
            {
                return null;
            }
        }
    }

    synchronized void invalidate()
    {
        if( null != m_invocationHandler )
        {
            m_invocationHandler.invalidate();
            m_invocationHandler = null;
        }
        m_object = null;
    }

    private Class[] getServiceClasses( final Object block,
                                       final ServiceDescriptor[] services )
    {
        final Class[] classes = new Class[ services.length + 1 ];
        final ClassLoader classLoader = block.getClass().getClassLoader();

        for( int i = 0; i < services.length; i++ )
        {
            try
            {
                classes[ i ] =
                classLoader.loadClass( services[ i ].getType() );
            }
            catch( final Throwable throwable )
            {
                //Ignore
            }
        }

        //Note that the proxy is still built using the
        //Block interface so that ComponentManagers can
        //still be used to provide blocks with services.
        //Block extends Component and thus the proxy
        //extends Component. The magic is that the Block
        //interface has no methods and thus will never cause
        //any issues for Proxy class.
        classes[ services.length ] = BLOCK_CLASS;
        return classes;
    }

    private static Class getBlockClass()
    {
        try
        {
            return Class.forName( "org.apache.avalon.phoenix.Block" );
        }
        catch( ClassNotFoundException e )
        {
            throw new IllegalStateException( "Can not find block class" );
        }
    }
}
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