| 1 | /* |
| 2 | * Copyright 2002-2008 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.support; |
| 18 | |
| 19 | import java.lang.annotation.Annotation; |
| 20 | import java.lang.annotation.ElementType; |
| 21 | import java.lang.annotation.Target; |
| 22 | import java.lang.reflect.Method; |
| 23 | import java.util.concurrent.atomic.AtomicReference; |
| 24 | |
| 25 | import org.springframework.aop.support.AopUtils; |
| 26 | import org.springframework.core.annotation.AnnotationUtils; |
| 27 | import org.springframework.util.Assert; |
| 28 | import org.springframework.util.ObjectUtils; |
| 29 | import org.springframework.util.ReflectionUtils; |
| 30 | |
| 31 | /** |
| 32 | * MethodResolver implementation that finds a <em>single</em> Method on the |
| 33 | * given Class that contains the specified annotation type. |
| 34 | * |
| 35 | * @author Mark Fisher |
| 36 | */ |
| 37 | public class AnnotationMethodResolver implements MethodResolver { |
| 38 | |
| 39 | private Class<? extends Annotation> annotationType; |
| 40 | |
| 41 | |
| 42 | /** |
| 43 | * Create a MethodResolver for the specified Method-level annotation type |
| 44 | */ |
| 45 | public AnnotationMethodResolver(Class<? extends Annotation> annotationType) { |
| 46 | Assert.notNull(annotationType, "annotationType must not be null"); |
| 47 | Assert.isTrue(ObjectUtils.containsElement( |
| 48 | annotationType.getAnnotation(Target.class).value(), ElementType.METHOD), |
| 49 | "Annotation [" + annotationType + "] is not a Method-level annotation."); |
| 50 | this.annotationType = annotationType; |
| 51 | } |
| 52 | |
| 53 | |
| 54 | /** |
| 55 | * Find a <em>single</em> Method on the Class of the given candidate object |
| 56 | * that contains the annotation type for which this resolver is searching. |
| 57 | * |
| 58 | * @param candidate the instance whose Class will be checked for the |
| 59 | * annotation |
| 60 | * |
| 61 | * @return a single matching Method instance or <code>null</code> if the |
| 62 | * candidate's Class contains no Methods with the specified annotation |
| 63 | * |
| 64 | * @throws IllegalArgumentException if more than one Method has the |
| 65 | * specified annotation |
| 66 | */ |
| 67 | @Override |
| 68 | public Method findMethod(Object candidate) { |
| 69 | Assert.notNull(candidate, "candidate object must not be null"); |
| 70 | Class<?> targetClass = AopUtils.getTargetClass(candidate); |
| 71 | if (targetClass == null) { |
| 72 | targetClass = candidate.getClass(); |
| 73 | } |
| 74 | return this.findMethod(targetClass); |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * Find a <em>single</em> Method on the given Class that contains the |
| 79 | * annotation type for which this resolver is searching. |
| 80 | * |
| 81 | * @param clazz the Class instance to check for the annotation |
| 82 | * |
| 83 | * @return a single matching Method instance or <code>null</code> if the |
| 84 | * Class contains no Methods with the specified annotation |
| 85 | * |
| 86 | * @throws IllegalArgumentException if more than one Method has the |
| 87 | * specified annotation |
| 88 | */ |
| 89 | @Override |
| 90 | public Method findMethod(final Class<?> clazz) { |
| 91 | Assert.notNull(clazz, "class must not be null"); |
| 92 | final AtomicReference<Method> annotatedMethod = new AtomicReference<Method>(); |
| 93 | ReflectionUtils.doWithMethods(clazz, new ReflectionUtils.MethodCallback() { |
| 94 | @Override |
| 95 | public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException { |
| 96 | Annotation annotation = AnnotationUtils.findAnnotation(method, annotationType); |
| 97 | if (annotation != null) { |
| 98 | Assert.isNull(annotatedMethod.get(), "found more than one method on target class [" |
| 99 | + clazz + "] with the annotation type [" + annotationType + "]"); |
| 100 | annotatedMethod.set(method); |
| 101 | } |
| 102 | } |
| 103 | }); |
| 104 | return annotatedMethod.get(); |
| 105 | } |
| 106 | |
| 107 | } |