IntegrationMessageHandlerMethodFactory.java

/*
 * Copyright 2017 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.integration.util;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;

import org.springframework.core.DefaultParameterNameDiscoverer;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.messaging.Message;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite;
import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
import org.springframework.messaging.handler.invocation.MethodArgumentResolutionException;

/**
 * @author Artem Bilan
 *
 * @since 5.0
 */
public class IntegrationMessageHandlerMethodFactory extends DefaultMessageHandlerMethodFactory {

	private final HandlerMethodArgumentResolverComposite argumentResolvers =
			new HandlerMethodArgumentResolverComposite();


	@Override
	public void setArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
		super.setArgumentResolvers(argumentResolvers);
		if (argumentResolvers == null) {
			this.argumentResolvers.clear();
			return;
		}
		this.argumentResolvers.addResolvers(argumentResolvers);
	}

	@Override
	public void afterPropertiesSet() {
		super.afterPropertiesSet();
		if (this.argumentResolvers.getResolvers().isEmpty()) {
			this.argumentResolvers.addResolvers(initArgumentResolvers());
		}
	}

	@Override
	public InvocableHandlerMethod createInvocableHandlerMethod(Object bean, Method method) {
		InvocableHandlerMethod handlerMethod = new IntegrationInvocableHandlerMethod(bean, method);
		handlerMethod.setMessageMethodArgumentResolvers(this.argumentResolvers);
		return handlerMethod;
	}

	private static class IntegrationInvocableHandlerMethod extends InvocableHandlerMethod {

		private HandlerMethodArgumentResolverComposite argumentResolvers;

		IntegrationInvocableHandlerMethod(Object bean, Method method) {
			super(bean, method);
			ParameterNameDiscoverer parameterNameDiscoverer = new DefaultParameterNameDiscoverer();
			for (MethodParameter parameter : getMethodParameters()) {
				GenericTypeResolver.resolveParameterType(parameter, getBeanType());
				parameter.initParameterNameDiscovery(parameterNameDiscoverer);
			}
		}

		@Override
		public void setParameterNameDiscoverer(ParameterNameDiscoverer parameterNameDiscoverer) {
			super.setParameterNameDiscoverer(parameterNameDiscoverer);
			for (MethodParameter parameter : getMethodParameters()) {
				parameter.initParameterNameDiscovery(parameterNameDiscoverer);
			}
		}

		@Override
		public void setMessageMethodArgumentResolvers(HandlerMethodArgumentResolverComposite argumentResolvers) {
			super.setMessageMethodArgumentResolvers(argumentResolvers);
			this.argumentResolvers = argumentResolvers;
		}

		public Object invoke(Message<?> message, Object... providedArgs) throws Exception {
			Object[] args = getMethodArgumentValues(message, providedArgs);
			if (logger.isTraceEnabled()) {
				logger.trace("Invoking '" + org.springframework.util.ClassUtils.getQualifiedMethodName(getMethod(), getBeanType()) +
						"' with arguments " + Arrays.toString(args));
			}
			Object returnValue = doInvoke(args);
			if (logger.isTraceEnabled()) {
				logger.trace("Method [" + org.springframework.util.ClassUtils.getQualifiedMethodName(getMethod(), getBeanType()) +
						"] returned [" + returnValue + "]");
			}
			return returnValue;
		}

		/**
		 * Get the method argument values for the current request.
		 */
		private Object[] getMethodArgumentValues(Message<?> message, Object... providedArgs) throws Exception {
			MethodParameter[] parameters = getMethodParameters();
			Object[] args = new Object[parameters.length];
			for (int i = 0; i < parameters.length; i++) {
				MethodParameter parameter = parameters[i];
				args[i] = resolveProvidedArgument(parameter, providedArgs);
				if (args[i] != null) {
					continue;
				}
				if (this.argumentResolvers.supportsParameter(parameter)) {
					try {
						args[i] = this.argumentResolvers.resolveArgument(parameter, message);
						continue;
					}
					catch (Exception ex) {
						if (logger.isDebugEnabled()) {
							logger.debug(getArgumentResolutionErrorMessage("Failed to resolve", i), ex);
						}
						throw ex;
					}
				}
				if (args[i] == null) {
					throw new MethodArgumentResolutionException(message, parameter,
							getArgumentResolutionErrorMessage("No suitable resolver for", i));
				}
			}
			return args;
		}

		private String getArgumentResolutionErrorMessage(String text, int index) {
			Class<?> paramType = getMethodParameters()[index].getParameterType();
			return text + " argument " + index + " of type '" + paramType.getName() + "'";
		}

		/**
		 * Attempt to resolve a method parameter from the list of provided argument values.
		 */
		private Object resolveProvidedArgument(MethodParameter parameter, Object... providedArgs) {
			if (providedArgs == null) {
				return null;
			}
			for (Object providedArg : providedArgs) {
				if (parameter.getParameterType().isInstance(providedArg)) {
					return providedArg;
				}
			}
			return null;
		}

	}

}