/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you 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.apache.shiro.aop;

 import java.lang.annotation.Annotation;

 import java.lang.reflect.Method;

 /**

  * Default {@code AnnotationResolver} implementation that merely inspects the

  * {@link MethodInvocation MethodInvocation}'s {@link MethodInvocation#getMethod() target method},

  * and returns {@code targetMethod}.{@link Method#getAnnotation(Class) getAnnotation(class)}.

  * <p/>

  * Unfortunately Java's default reflection API for Annotations is not very robust, and this logic

  * may not be enough - if the incoming method invocation represents a method from an interface,

  * this default logic would not discover the annotation if it existed on the method implementation

  * directly (as opposed to being defined directly in the interface definition).

  * <p/>

  * More complex class hierarchy traversal logic is required to exhaust a method's target object's

  * classes, parent classes, interfaces and parent interfaces.  That logic will likely be added

  * to this implementation in due time, but for now, this implementation relies on the JDK's default

  * {@link Method#getAnnotation(Class) Method.getAnnotation(class)} logic.

  *

  * @since 1.1

  */

 public class DefaultAnnotationResolver implements AnnotationResolver {

     /**

      * Returns {@code methodInvocation.}{@link org.apache.shiro.aop.MethodInvocation#getMethod() getMethod()}.{@link Method#getAnnotation(Class) getAnnotation(clazz)}.

      *

      * @param mi    the intercepted method to be invoked.

      * @param clazz the annotation class to use to find an annotation instance on the method.

      * @return the discovered annotation or {@code null} if an annotation instance could not be

      *         found.

      */

     public Annotation getAnnotation(MethodInvocation mi, Class<? extends Annotation> clazz) {

         if (mi == null) {

             throw new IllegalArgumentException("method argument cannot be null");

         }

         Method m = mi.getMethod();

         if (m == null) {

             String msg = MethodInvocation.class.getName() + " parameter incorrectly constructed.  getMethod() returned null";

             throw new IllegalArgumentException(msg);

         }

         Annotation annotation = m.getAnnotation(clazz);

         return annotation == null ? mi.getThis().getClass().getAnnotation(clazz) : annotation;

     }

 }