/*
* Copyright 2002-2013 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.messaging.handler.annotation.support;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.messaging.handler.HandlerMethodSelector;
import org.springframework.messaging.handler.annotation.MessageExceptionHandler;
import org.springframework.messaging.handler.invocation.AbstractExceptionHandlerMethodResolver;
import org.springframework.util.ReflectionUtils.MethodFilter;
/**
* A sub-class of {@link AbstractExceptionHandlerMethodResolver} that looks for
* {@link MessageExceptionHandler}-annotated methods in a given class. The actual
* exception types handled are extracted either from the annotation, if present,
* or from the method signature as a fallback option.
*
* @author Rossen Stoyanchev
* @since 4.0
*/
public class AnnotationExceptionHandlerMethodResolver extends AbstractExceptionHandlerMethodResolver {
/**
* A constructor that finds {@link MessageExceptionHandler} methods in the given type.
* @param handlerType the type to introspect
*/
public AnnotationExceptionHandlerMethodResolver(Class<?> handlerType) {
super(initExceptionMappings(handlerType));
}
private static Map<Class<? extends Throwable>, Method> initExceptionMappings(Class<?> handlerType) {
Map<Class<? extends Throwable>, Method> result = new HashMap<Class<? extends Throwable>, Method>();
for (Method method : HandlerMethodSelector.selectMethods(handlerType, EXCEPTION_HANDLER_METHOD_FILTER)) {
for (Class<? extends Throwable> exceptionType : getMappedExceptions(method)) {
Method oldMethod = result.put(exceptionType, method);
if (oldMethod != null && !oldMethod.equals(method)) {
throw new IllegalStateException(
"Ambiguous @ExceptionHandler method mapped for [" + exceptionType + "]: {" +
oldMethod + ", " + method + "}.");
}
}
}
return result;
}
private static List<Class<? extends Throwable>> getMappedExceptions(Method method) {
List<Class<? extends Throwable>> result = new ArrayList<Class<? extends Throwable>>();
MessageExceptionHandler annot = AnnotationUtils.findAnnotation(method, MessageExceptionHandler.class);
result.addAll(Arrays.asList(annot.value()));
if (result.isEmpty()) {
result.addAll(getExceptionsFromMethodSignature(method));
}
return result;
}
/** A filter for selecting annotated exception handling methods. */
public final static MethodFilter EXCEPTION_HANDLER_METHOD_FILTER = new MethodFilter() {
@Override
public boolean matches(Method method) {
return AnnotationUtils.findAnnotation(method, MessageExceptionHandler.class) != null;
}
};
}