org.zkybase.kite.throttle.interceptor.AnnotationThrottleSource.java Source code

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Here is the source code for org.zkybase.kite.throttle.interceptor.AnnotationThrottleSource.java

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/*
 * Copyright (c) 2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.zkybase.kite.throttle.interceptor;

import java.io.Serializable;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.zkybase.kite.annotation.GuardedByThrottle;
import org.zkybase.kite.throttle.ThrottleTemplate;

// TODO Consider implementing throttle. See Spring's
// AbstractFallbackTransactionAttributeSource

/**
 * @version $Id$
 * @author Willie Wheeler
 */
@SuppressWarnings("serial")
public class AnnotationThrottleSource implements ThrottleSource, BeanFactoryAware, Serializable {

    private static final Class<GuardedByThrottle> ANN_CLASS = GuardedByThrottle.class;
    //   private static Logger log = LoggerFactory.getLogger(AnnotationThrottleSource.class);

    private BeanFactory beanFactory;

    /**
     * @param beanFactory
     */
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = beanFactory;
    }

    public ThrottleTemplate getThrottle(Method method, Class<?> targetClass) {
        Assert.notNull(method, "method can't be null");

        // Method may be on an interface, but we need annotations from the
        // target class. If target class is null, method will be unchanged.
        Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);

        // If we are dealing with a method with generic parameters, find the
        // original method.
        specificMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);

        ThrottleTemplate throttle = parseAnnotation(specificMethod);
        if (throttle != null) {
            return throttle;
        } else {
            return parseAnnotation(method);
        }
    }

    // Based on SpringTransactionAnnotationParser
    private ThrottleTemplate parseAnnotation(AnnotatedElement elem) {
        assert (elem != null);

        GuardedByThrottle ann = elem.getAnnotation(ANN_CLASS);

        // Meta-annotation search (Spring 3)
        // FIXME It looks like this is getting annotations off the element, not
        // off of other annotations...
        //      if (ann == null) {
        //         for (Annotation metaAnn : elem.getAnnotations()) {
        //            ann = metaAnn.annotationType().getAnnotation(ANN_CLASS);
        //            if (ann != null) { break; }
        //         }
        //      }

        // If ann is null, then this returns null
        return parseAnnotation(ann);
    }

    /**
     * @param ann
     *            annotation (<code>null</code> ok)
     * @return referenced throttle, or <code>null</code> if <code>ann</code> is
     *         <code>null</code>
     * @throws BeansException
     *             if the annotation references a throttle that doesn't exist
     */
    private ThrottleTemplate parseAnnotation(GuardedByThrottle ann) {
        if (ann == null) {
            return null;
        }

        // Throws BeansException if the bean can't be found
        return beanFactory.getBean(ann.value(), ThrottleTemplate.class);
    }
}