001/*
002 * Copyright 2002-2015 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.messaging.handler.annotation.support;
018
019import java.lang.reflect.Method;
020import java.util.ArrayList;
021import java.util.Arrays;
022import java.util.HashMap;
023import java.util.List;
024import java.util.Map;
025
026import org.springframework.core.MethodIntrospector;
027import org.springframework.core.annotation.AnnotationUtils;
028import org.springframework.messaging.handler.annotation.MessageExceptionHandler;
029import org.springframework.messaging.handler.invocation.AbstractExceptionHandlerMethodResolver;
030import org.springframework.util.ReflectionUtils.MethodFilter;
031
032/**
033 * A sub-class of {@link AbstractExceptionHandlerMethodResolver} that looks for
034 * {@link MessageExceptionHandler}-annotated methods in a given class. The actual
035 * exception types handled are extracted either from the annotation, if present,
036 * or from the method signature as a fallback option.
037 *
038 * @author Rossen Stoyanchev
039 * @since 4.0
040 */
041public class AnnotationExceptionHandlerMethodResolver extends AbstractExceptionHandlerMethodResolver {
042
043        /**
044         * A constructor that finds {@link MessageExceptionHandler} methods in the given type.
045         * @param handlerType the type to introspect
046         */
047        public AnnotationExceptionHandlerMethodResolver(Class<?> handlerType) {
048                super(initExceptionMappings(handlerType));
049        }
050
051        private static Map<Class<? extends Throwable>, Method> initExceptionMappings(Class<?> handlerType) {
052                Map<Method, MessageExceptionHandler> methods = MethodIntrospector.selectMethods(handlerType,
053                                new MethodIntrospector.MetadataLookup<MessageExceptionHandler>() {
054                                        @Override
055                                        public MessageExceptionHandler inspect(Method method) {
056                                                return AnnotationUtils.findAnnotation(method, MessageExceptionHandler.class);
057                                        }
058                                });
059
060                Map<Class<? extends Throwable>, Method> result = new HashMap<Class<? extends Throwable>, Method>();
061                for (Map.Entry<Method, MessageExceptionHandler> entry : methods.entrySet()) {
062                        Method method = entry.getKey();
063                        List<Class<? extends Throwable>> exceptionTypes = new ArrayList<Class<? extends Throwable>>();
064                        exceptionTypes.addAll(Arrays.asList(entry.getValue().value()));
065                        if (exceptionTypes.isEmpty()) {
066                                exceptionTypes.addAll(getExceptionsFromMethodSignature(method));
067                        }
068                        for (Class<? extends Throwable> exceptionType : exceptionTypes) {
069                                Method oldMethod = result.put(exceptionType, method);
070                                if (oldMethod != null && !oldMethod.equals(method)) {
071                                        throw new IllegalStateException("Ambiguous @ExceptionHandler method mapped for [" +
072                                                        exceptionType + "]: {" + oldMethod + ", " + method + "}");
073                                }
074                        }
075                }
076                return result;
077        }
078
079
080        /**
081         * A filter for selecting annotated exception handling methods.
082         * @deprecated as of Spring 4.2.3, since it isn't used anymore
083         */
084        @Deprecated
085        public final static MethodFilter EXCEPTION_HANDLER_METHOD_FILTER = new MethodFilter() {
086
087                @Override
088                public boolean matches(Method method) {
089                        return AnnotationUtils.findAnnotation(method, MessageExceptionHandler.class) != null;
090                }
091        };
092
093}