| 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 | package org.springframework.batch.support; |
| 17 | |
| 18 | import java.lang.annotation.Annotation; |
| 19 | import java.lang.annotation.ElementType; |
| 20 | import java.lang.annotation.Target; |
| 21 | import java.lang.reflect.Method; |
| 22 | import java.util.concurrent.atomic.AtomicReference; |
| 23 | |
| 24 | import org.springframework.aop.framework.Advised; |
| 25 | import org.springframework.core.annotation.AnnotationUtils; |
| 26 | import org.springframework.util.Assert; |
| 27 | import org.springframework.util.ClassUtils; |
| 28 | import org.springframework.util.ObjectUtils; |
| 29 | import org.springframework.util.ReflectionUtils; |
| 30 | |
| 31 | /** |
| 32 | * Utility methods for create MethodInvoker instances. |
| 33 | * |
| 34 | * @author Lucas Ward |
| 35 | * @since 2.0 |
| 36 | */ |
| 37 | public class MethodInvokerUtils { |
| 38 | |
| 39 | /** |
| 40 | * Create a {@link MethodInvoker} using the provided method name to search. |
| 41 | * |
| 42 | * @param object to be invoked |
| 43 | * @param methodName of the method to be invoked |
| 44 | * @param paramsRequired boolean indicating whether the parameters are |
| 45 | * required, if false, a no args version of the method will be searched for. |
| 46 | * @param paramTypes - parameter types of the method to search for. |
| 47 | * @return MethodInvoker if the method is found, null if it is not. |
| 48 | */ |
| 49 | public static MethodInvoker getMethodInvokerByName(Object object, String methodName, boolean paramsRequired, |
| 50 | Class<?>... paramTypes) { |
| 51 | Assert.notNull(object, "Object to invoke must not be null"); |
| 52 | Method method = ClassUtils.getMethodIfAvailable(object.getClass(), methodName, paramTypes); |
| 53 | if (method == null) { |
| 54 | String errorMsg = "no method found with name [" + methodName + "] on class [" |
| 55 | + object.getClass().getSimpleName() + "] compatable with the signature [" |
| 56 | + getParamTypesString(paramTypes) + "]."; |
| 57 | Assert.isTrue(!paramsRequired, errorMsg); |
| 58 | // if no method was found for the given parameters, and the |
| 59 | // parameters aren't required, then try with no params |
| 60 | method = ClassUtils.getMethodIfAvailable(object.getClass(), methodName, new Class[] {}); |
| 61 | Assert.notNull(method, errorMsg); |
| 62 | } |
| 63 | return new SimpleMethodInvoker(object, method); |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * Create a String representation of the array of parameter types. |
| 68 | * |
| 69 | * @param paramTypes |
| 70 | * @return String |
| 71 | */ |
| 72 | public static String getParamTypesString(Class<?>... paramTypes) { |
| 73 | StringBuffer paramTypesList = new StringBuffer("("); |
| 74 | for (int i = 0; i < paramTypes.length; i++) { |
| 75 | paramTypesList.append(paramTypes[i].getSimpleName()); |
| 76 | if (i + 1 < paramTypes.length) { |
| 77 | paramTypesList.append(", "); |
| 78 | } |
| 79 | } |
| 80 | return paramTypesList.append(")").toString(); |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * Create a {@link MethodInvoker} using the provided interface, and method |
| 85 | * name from that interface. |
| 86 | * |
| 87 | * @param cls the interface to search for the method named |
| 88 | * @param methodName of the method to be invoked |
| 89 | * @param object to be invoked |
| 90 | * @param paramTypes - parameter types of the method to search for. |
| 91 | * @return MethodInvoker if the method is found, null if it is not. |
| 92 | */ |
| 93 | public static MethodInvoker getMethodInvokerForInterface(Class<?> cls, String methodName, Object object, |
| 94 | Class<?>... paramTypes) { |
| 95 | |
| 96 | if (cls.isAssignableFrom(object.getClass())) { |
| 97 | return MethodInvokerUtils.getMethodInvokerByName(object, methodName, true, paramTypes); |
| 98 | } |
| 99 | else { |
| 100 | return null; |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Create a MethodInvoker from the delegate based on the annotationType. |
| 106 | * Ensure that the annotated method has a valid set of parameters. |
| 107 | * |
| 108 | * @param annotationType the annotation to scan for |
| 109 | * @param target the target object |
| 110 | * @param expectedParamTypes the expected parameter types for the method |
| 111 | * @return a MethodInvoker |
| 112 | */ |
| 113 | public static MethodInvoker getMethodInvokerByAnnotation(final Class<? extends Annotation> annotationType, |
| 114 | final Object target, final Class<?>... expectedParamTypes) { |
| 115 | MethodInvoker mi = MethodInvokerUtils.getMethodInvokerByAnnotation(annotationType, target); |
| 116 | final Class<?> targetClass = (target instanceof Advised) ? ((Advised) target).getTargetSource() |
| 117 | .getTargetClass() : target.getClass(); |
| 118 | if (mi != null) { |
| 119 | ReflectionUtils.doWithMethods(targetClass, new ReflectionUtils.MethodCallback() { |
| 120 | @Override |
| 121 | public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException { |
| 122 | Annotation annotation = AnnotationUtils.findAnnotation(method, annotationType); |
| 123 | if (annotation != null) { |
| 124 | Class<?>[] paramTypes = method.getParameterTypes(); |
| 125 | if (paramTypes.length > 0) { |
| 126 | String errorMsg = "The method [" + method.getName() + "] on target class [" |
| 127 | + targetClass.getSimpleName() + "] is incompatable with the signature [" |
| 128 | + getParamTypesString(expectedParamTypes) + "] expected for the annotation [" |
| 129 | + annotationType.getSimpleName() + "]."; |
| 130 | |
| 131 | Assert.isTrue(paramTypes.length == expectedParamTypes.length, errorMsg); |
| 132 | for (int i = 0; i < paramTypes.length; i++) { |
| 133 | Assert.isTrue(expectedParamTypes[i].isAssignableFrom(paramTypes[i]), errorMsg); |
| 134 | } |
| 135 | } |
| 136 | } |
| 137 | } |
| 138 | }); |
| 139 | } |
| 140 | return mi; |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * Create {@link MethodInvoker} for the method with the provided annotation |
| 145 | * on the provided object. Annotations that cannot be applied to methods |
| 146 | * (i.e. that aren't annotated with an element type of METHOD) will cause an |
| 147 | * exception to be thrown. |
| 148 | * |
| 149 | * @param annotationType to be searched for |
| 150 | * @param target to be invoked |
| 151 | * @return MethodInvoker for the provided annotation, null if none is found. |
| 152 | */ |
| 153 | public static MethodInvoker getMethodInvokerByAnnotation(final Class<? extends Annotation> annotationType, |
| 154 | final Object target) { |
| 155 | Assert.notNull(target, "Target must not be null"); |
| 156 | Assert.notNull(annotationType, "AnnotationType must not be null"); |
| 157 | Assert.isTrue(ObjectUtils.containsElement(annotationType.getAnnotation(Target.class).value(), |
| 158 | ElementType.METHOD), "Annotation [" + annotationType + "] is not a Method-level annotation."); |
| 159 | final Class<?> targetClass = (target instanceof Advised) ? ((Advised) target).getTargetSource() |
| 160 | .getTargetClass() : target.getClass(); |
| 161 | if (targetClass == null) { |
| 162 | // Proxy with no target cannot have annotations |
| 163 | return null; |
| 164 | } |
| 165 | final AtomicReference<Method> annotatedMethod = new AtomicReference<Method>(); |
| 166 | ReflectionUtils.doWithMethods(targetClass, new ReflectionUtils.MethodCallback() { |
| 167 | @Override |
| 168 | public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException { |
| 169 | Annotation annotation = AnnotationUtils.findAnnotation(method, annotationType); |
| 170 | if (annotation != null) { |
| 171 | Assert.isNull(annotatedMethod.get(), "found more than one method on target class [" |
| 172 | + targetClass.getSimpleName() + "] with the annotation type [" |
| 173 | + annotationType.getSimpleName() + "]."); |
| 174 | annotatedMethod.set(method); |
| 175 | } |
| 176 | } |
| 177 | }); |
| 178 | Method method = annotatedMethod.get(); |
| 179 | if (method == null) { |
| 180 | return null; |
| 181 | } |
| 182 | else { |
| 183 | return new SimpleMethodInvoker(target, annotatedMethod.get()); |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | /** |
| 188 | * Create a {@link MethodInvoker} for the delegate from a single public |
| 189 | * method. |
| 190 | * |
| 191 | * @param target an object to search for an appropriate method |
| 192 | * @return a MethodInvoker that calls a method on the delegate |
| 193 | */ |
| 194 | public static <C, T> MethodInvoker getMethodInvokerForSingleArgument(Object target) { |
| 195 | final AtomicReference<Method> methodHolder = new AtomicReference<Method>(); |
| 196 | ReflectionUtils.doWithMethods(target.getClass(), new ReflectionUtils.MethodCallback() { |
| 197 | @Override |
| 198 | public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException { |
| 199 | if (method.getParameterTypes() == null || method.getParameterTypes().length != 1) { |
| 200 | return; |
| 201 | } |
| 202 | if (method.getReturnType().equals(Void.TYPE) || ReflectionUtils.isEqualsMethod(method)) { |
| 203 | return; |
| 204 | } |
| 205 | Assert.state(methodHolder.get() == null, |
| 206 | "More than one non-void public method detected with single argument."); |
| 207 | methodHolder.set(method); |
| 208 | } |
| 209 | }); |
| 210 | Method method = methodHolder.get(); |
| 211 | return new SimpleMethodInvoker(target, method); |
| 212 | } |
| 213 | } |