/*
 * Copyright (c) 2010-2016. Axon Framework
 *
 * 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.axonframework.messaging.interceptors;

import org.axonframework.messaging.InterceptorChain;
import org.axonframework.messaging.Message;
import org.axonframework.messaging.MessageDispatchInterceptor;
import org.axonframework.messaging.MessageHandlerInterceptor;
import org.axonframework.messaging.unitofwork.UnitOfWork;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.List;
import java.util.function.BiFunction;

import static java.lang.String.format;

/**
 * {@link MessageDispatchInterceptor} and {@link MessageHandlerInterceptor} implementation that logs dispatched and
 * incoming messages, and their result, to a SLF4J logger. Allows configuration of the name under which the logger
 * should log the statements.
 * <p/>
 * Dispatched, incoming messages and successful executions are logged at the {@code INFO} level. Processing errors are
 * logged using the {@code WARN} level.
 *
 * @author Allard Buijze
 * @since 0.6
 */
public class LoggingInterceptor<T extends Message<?>>
        implements MessageDispatchInterceptor<T>, MessageHandlerInterceptor<T> {

    private final Logger logger;

    /**
     * Initialize the LoggingInterceptor with the given {@code loggerName}. The actual logging implementation will
     * use this name to decide the appropriate log level and location. See the documentation of your logging
     * implementation for more information.
     *
     * @param loggerName the name of the logger
     */
    public LoggingInterceptor(String loggerName) {
        this.logger = LoggerFactory.getLogger(loggerName);
    }

    /**
     * Initialize the LoggingInterceptor with the default logger name, which is the fully qualified class name of this
     * logger.
     *
     * @see LoggingInterceptor#LoggingInterceptor(String)
     */
    public LoggingInterceptor() {
        this.logger = LoggerFactory.getLogger(LoggingInterceptor.class);
    }

    @Override
    public BiFunction<Integer, T, T> handle(List<? extends T> messages) {
        return (i, message) -> {
            logger.info("Dispatched messages: [{}]", message.getPayloadType().getSimpleName());
            return message;
        };
    }

    @Override
    public Object handle(UnitOfWork<? extends T> unitOfWork, InterceptorChain interceptorChain)
            throws Exception {
        T message = unitOfWork.getMessage();
        logger.info("Incoming message: [{}]", message.getPayloadType().getSimpleName());
        try {
            Object returnValue = interceptorChain.proceed();
            logger.info("[{}] executed successfully with a [{}] return value",
                        message.getPayloadType().getSimpleName(),
                        returnValue == null ? "null" : returnValue.getClass().getSimpleName());
            return returnValue;
        } catch (Exception t) {
            logger.warn(format("[%s] execution failed:", message.getPayloadType().getSimpleName()), t);
            throw t;
        }
    }
}

@@ -21,17 +21,17 @@
 2010-201
-6
+9
 . Axon F

Update messaging/src/main/java/org/axonframework/messaging/interceptors/LoggingInterceptor.java