View Javadoc

1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.shiro.aop;
20  
21  import java.lang.annotation.Annotation;
22  import java.lang.reflect.Method;
23  
24  /**
25   * Default {@code AnnotationResolver} implementation that merely inspects the
26   * {@link MethodInvocation MethodInvocation}'s {@link MethodInvocation#getMethod() target method},
27   * and returns {@code targetMethod}.{@link Method#getAnnotation(Class) getAnnotation(class)}.
28   * <p/>
29   * Unfortunately Java's default reflection API for Annotations is not very robust, and this logic
30   * may not be enough - if the incoming method invocation represents a method from an interface,
31   * this default logic would not discover the annotation if it existed on the method implementation
32   * directly (as opposed to being defined directly in the interface definition).
33   * <p/>
34   * More complex class hierarchy traversal logic is required to exhaust a method's target object's
35   * classes, parent classes, interfaces and parent interfaces.  That logic will likely be added
36   * to this implementation in due time, but for now, this implementation relies on the JDK's default
37   * {@link Method#getAnnotation(Class) Method.getAnnotation(class)} logic.
38   *
39   * @since 1.1
40   */
41  public class DefaultAnnotationResolver implements AnnotationResolver {
42  
43      /**
44       * Returns {@code methodInvocation.}{@link org.apache.shiro.aop.MethodInvocation#getMethod() getMethod()}.{@link Method#getAnnotation(Class) getAnnotation(clazz)}.
45       *
46       * @param mi    the intercepted method to be invoked.
47       * @param clazz the annotation class to use to find an annotation instance on the method.
48       * @return the discovered annotation or {@code null} if an annotation instance could not be
49       *         found.
50       */
51      public Annotation getAnnotation(MethodInvocation mi, Class<? extends Annotation> clazz) {
52          if (mi == null) {
53              throw new IllegalArgumentException("method argument cannot be null");
54          }
55          Method m = mi.getMethod();
56          if (m == null) {
57              String msg = MethodInvocation.class.getName() + " parameter incorrectly constructed.  getMethod() returned null";
58              throw new IllegalArgumentException(msg);
59  
60          }
61          Annotation annotation = m.getAnnotation(clazz);
62          return annotation == null ? mi.getThis().getClass().getAnnotation(clazz) : annotation;
63      }
64  }