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| 1 | +/* |
| 2 | + * Copyright 2002-2015 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.core; |
| 18 | + |
| 19 | +import java.lang.reflect.Method; |
| 20 | +import java.lang.reflect.Proxy; |
| 21 | +import java.util.Arrays; |
| 22 | +import java.util.LinkedHashMap; |
| 23 | +import java.util.LinkedHashSet; |
| 24 | +import java.util.Map; |
| 25 | +import java.util.Set; |
| 26 | + |
| 27 | +import org.springframework.util.ClassUtils; |
| 28 | +import org.springframework.util.ReflectionUtils; |
| 29 | + |
| 30 | +/** |
| 31 | + * Defines the algorithm for searching for metadata-associated methods exhaustively |
| 32 | + * including interfaces and parent classes while also dealing with parameterized methods |
| 33 | + * as well as common scenarios encountered with interface and class-based proxies. |
| 34 | + * |
| 35 | + * <p>Typically, but not necessarily, used for finding annotated handler methods. |
| 36 | + * |
| 37 | + * @author Juergen Hoeller |
| 38 | + * @author Rossen Stoyanchev |
| 39 | + * @since 4.2.3 |
| 40 | + */ |
| 41 | +public abstract class MethodIntrospector { |
| 42 | + |
| 43 | + /** |
| 44 | + * Select methods on the given target type based on the lookup of associated metadata. |
| 45 | + * <p>Callers define methods of interest through the {@link MetadataLookup} parameter, |
| 46 | + * allowing to collect the associated metadata into the result map. |
| 47 | + * @param targetType the target type to search methods on |
| 48 | + * @param metadataLookup a {@link MetadataLookup} callback to inspect methods of interest, |
| 49 | + * returning non-null metadata to be associated with a given method if there is a match, |
| 50 | + * or {@code null} for no match |
| 51 | + * @return the selected methods associated with their metadata (in the order of retrieval), |
| 52 | + * or an empty map in case of no match |
| 53 | + */ |
| 54 | + public static <T> Map<Method, T> selectMethods(Class<?> targetType, final MetadataLookup<T> metadataLookup) { |
| 55 | + final Map<Method, T> methodMap = new LinkedHashMap<Method, T>(); |
| 56 | + Set<Class<?>> handlerTypes = new LinkedHashSet<Class<?>>(); |
| 57 | + Class<?> specificHandlerType = null; |
| 58 | + |
| 59 | + if (!Proxy.isProxyClass(targetType)) { |
| 60 | + handlerTypes.add(targetType); |
| 61 | + specificHandlerType = targetType; |
| 62 | + } |
| 63 | + handlerTypes.addAll(Arrays.asList(targetType.getInterfaces())); |
| 64 | + |
| 65 | + for (Class<?> currentHandlerType : handlerTypes) { |
| 66 | + final Class<?> targetClass = (specificHandlerType != null ? specificHandlerType : currentHandlerType); |
| 67 | + |
| 68 | + ReflectionUtils.doWithMethods(currentHandlerType, new ReflectionUtils.MethodCallback() { |
| 69 | + @Override |
| 70 | + public void doWith(Method method) { |
| 71 | + Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass); |
| 72 | + T result = metadataLookup.inspect(specificMethod); |
| 73 | + if (result != null) { |
| 74 | + Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(specificMethod); |
| 75 | + if (bridgedMethod == specificMethod || metadataLookup.inspect(bridgedMethod) == null) { |
| 76 | + methodMap.put(specificMethod, result); |
| 77 | + } |
| 78 | + } |
| 79 | + } |
| 80 | + }, ReflectionUtils.USER_DECLARED_METHODS); |
| 81 | + } |
| 82 | + |
| 83 | + return methodMap; |
| 84 | + } |
| 85 | + |
| 86 | + /** |
| 87 | + * Select methods on the given target type based on a filter. |
| 88 | + * <p>Callers define methods of interest through the |
| 89 | + * {@link ReflectionUtils.MethodFilter} parameter. |
| 90 | + * @param targetType the target type to search methods on |
| 91 | + * @param methodFilter a {@link ReflectionUtils.MethodFilter} to help |
| 92 | + * recognize handler methods of interest |
| 93 | + * @return the selected methods, or an empty set in case of no match |
| 94 | + */ |
| 95 | + public static Set<Method> selectMethods(Class<?> targetType, final ReflectionUtils.MethodFilter methodFilter) { |
| 96 | + return selectMethods(targetType, new MetadataLookup<Boolean>() { |
| 97 | + @Override |
| 98 | + public Boolean inspect(Method method) { |
| 99 | + return (methodFilter.matches(method) ? Boolean.TRUE : null); |
| 100 | + } |
| 101 | + }).keySet(); |
| 102 | + } |
| 103 | + |
| 104 | + /** |
| 105 | + * Select an invocable method on the target type: either the given method itself |
| 106 | + * if actually exposed on the target type, or otherwise a corresponding method |
| 107 | + * on one of the target type's interfaces or on the target type itself. |
| 108 | + * <p>Matches on user-declared interfaces will be preferred since they are likely |
| 109 | + * to contain relevant metadata that corresponds to the method on the target class. |
| 110 | + * @param method the method to check |
| 111 | + * @param targetType the target type to search methods on |
| 112 | + * (typically an interface-based JDK proxy) |
| 113 | + * @return a corresponding invocable method on the target type |
| 114 | + */ |
| 115 | + public static Method selectInvocableMethod(Method method, Class<?> targetType) { |
| 116 | + if (method.getDeclaringClass().isAssignableFrom(targetType)) { |
| 117 | + return method; |
| 118 | + } |
| 119 | + try { |
| 120 | + for (Class<?> ifc : targetType.getInterfaces()) { |
| 121 | + try { |
| 122 | + return ifc.getMethod(method.getName(), method.getParameterTypes()); |
| 123 | + } |
| 124 | + catch (NoSuchMethodException ex) { |
| 125 | + // Alright, not on this interface then... |
| 126 | + } |
| 127 | + } |
| 128 | + // A final desperate attempt on the proxy class itself... |
| 129 | + return targetType.getMethod(method.getName(), method.getParameterTypes()); |
| 130 | + } |
| 131 | + catch (NoSuchMethodException ex) { |
| 132 | + throw new IllegalStateException(String.format( |
| 133 | + "Need to invoke method '%s' declared on target class '%s', " + |
| 134 | + "but not found in any interface(s) of the exposed proxy type. " + |
| 135 | + "Either pull the method up to an interface or switch to CGLIB " + |
| 136 | + "proxies by enforcing proxy-target-class mode in your configuration.", |
| 137 | + method.getName(), method.getDeclaringClass().getSimpleName())); |
| 138 | + } |
| 139 | + } |
| 140 | + |
| 141 | + |
| 142 | + /** |
| 143 | + * A callback interface for metadata lookup on a given method. |
| 144 | + * @param <T> the type of metadata returned |
| 145 | + */ |
| 146 | + public interface MetadataLookup<T> { |
| 147 | + |
| 148 | + /** |
| 149 | + * Perform a lookup on the given method and return associated metadata, if any. |
| 150 | + * @param method the method to inspect |
| 151 | + * @return non-null metadata to be associated with a method if there is a match, |
| 152 | + * or {@code null} for no match |
| 153 | + */ |
| 154 | + T inspect(Method method); |
| 155 | + } |
| 156 | + |
| 157 | +} |
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