AnnotationSupport.java

/*
 * Copyright (c) 2012-2015 The original author or authors
 * ------------------------------------------------------
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Apache License v2.0 which accompanies this distribution.
 *
 * The Eclipse Public License is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * The Apache License v2.0 is available at
 * http://www.opensource.org/licenses/apache2.0.php
 *
 * You may elect to redistribute this code under either of these licenses.
 */
package org.eclipse.moquette.spi.impl;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.moquette.proto.messages.AbstractMessage;

/**
 * Annotation @MQTTMessage helper class.
 * 
 * It has the responsibility to identify the @MQTTMessage method of a given instance or class and define an easy access to invoke them.
 * 
 * @author andrea
 */
class AnnotationSupport {

	private final Map<Class, Method> messageClassToMethod = new HashMap<Class, Method>();

	private Object targetInstance;

	void processAnnotations(Object instance) {
		targetInstance = instance;
		Class instanceCls = instance.getClass();
		Method[] allMethods = instanceCls.getDeclaredMethods();
		for (Method m : allMethods) {
			MQTTMessage annotation = m.getAnnotation(MQTTMessage.class);
			if (annotation == null) {
				continue;
			}
			Class mqttMessageClass = annotation.message();
			messageClassToMethod.put(mqttMessageClass, m);
		}
	}

	/**
	 * Dispatch a call to the wrapped target invoking the method that match the msg class.
	 * 
	 * @throws RuntimeException
	 *             if the message can't be routed to any annotated method, or if there are any errors during invocation.
	 */
	void dispatch(org.red5.server.mqtt.ServerChannel session, AbstractMessage msg) {
		Method targetMethod = this.messageClassToMethod.get(msg.getClass());
		if (targetMethod == null) {
			throw new RuntimeException("Can't dispatch to any @MQTTMessage marked the message: " + msg);
		}
		try {
			targetMethod.invoke(targetInstance, session, msg);
		} catch (Exception ex) {
			throw new RuntimeException(ex);
		}
	}
}