AnnotationIntrospector.java

// ========================================================================
// Copyright (c) 2006-2009 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at 
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses. 
// ========================================================================

package org.eclipse.jetty.annotations;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.jetty.util.log.Log;

/**
 * AnnotationIntrospector
 *
 *
 */
public class AnnotationIntrospector
{    
    protected List<IntrospectableAnnotationHandler> _handlers = new ArrayList<IntrospectableAnnotationHandler>();
    
    
    /**
     * IntrospectableAnnotationHandler
     *
     * Interface for all handlers that wish to introspect a class to find a particular annotation
     */
    public interface IntrospectableAnnotationHandler
    {
        public void handle(Class clazz);
    }
    
    
    
    /**
     * AbstractIntrospectableAnnotationHandler
     *
     * Base class for handlers that introspect a class to find a particular annotation.
     * A handler can optionally introspect the parent hierarchy of a class.
     */
    public static abstract class AbstractIntrospectableAnnotationHandler implements IntrospectableAnnotationHandler
    {
        private boolean _introspectAncestors;
        
        public abstract void doHandle(Class clazz);
        
        
        public AbstractIntrospectableAnnotationHandler(boolean introspectAncestors)
        {
            _introspectAncestors = introspectAncestors;
        }
        
        public void handle(Class clazz)
        {
            Class c = clazz;
            
            //process the whole inheritance hierarchy for the class
            while (c!=null && (!c.equals(Object.class)))
            {
                doHandle(c);
                if (!_introspectAncestors)
                    break;
                
                c = c.getSuperclass();
            }   
        }
    }
    
    public void registerHandler (IntrospectableAnnotationHandler handler)
    {
        _handlers.add(handler);
    }
    
    public void introspect (Class clazz)
    {
        if (_handlers == null)
            return;
        if (clazz == null)
            return;
        
        for (IntrospectableAnnotationHandler handler:_handlers)
        {
            try
            {
                handler.handle(clazz);
            }
            catch (RuntimeException e)
            {
                throw e;
            }
            catch (Exception e)
            {
                throw new RuntimeException(e);
            }
        }
     
    }
}