/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.mina.handler.demux;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.mina.common.IoHandler;
import org.apache.mina.common.IoHandlerAdapter;
import org.apache.mina.common.IoSession;
import org.apache.mina.common.UnknownMessageTypeException;
import org.apache.mina.util.IdentityHashSet;
/**
* A {@link IoHandler} that demuxes <code>messageReceived</code> events
* to the appropriate {@link MessageHandler}.
* <p>
* You can freely register and deregister {@link MessageHandler}s using
* {@link #addReceivedMessageHandler(Class, MessageHandler)} and
* {@link #removeReceivedMessageHandler(Class)}.
* </p>
* <p>
* When <code>message</code> is received through a call to
* {@link #messageReceived(IoSession, Object)} the class of the
* <code>message</code> object will be used to find a {@link MessageHandler} for
* that particular message type. If no {@link MessageHandler} instance can be
* found for the immediate class (i.e. <code>message.getClass()</code>) the
* interfaces implemented by the immediate class will be searched in depth-first
* order. If no match can be found for any of the interfaces the search will be
* repeated recursively for the superclass of the immediate class
* (i.e. <code>message.getClass().getSuperclass()</code>).
* </p>
* <p>
* Consider the following type hierarchy (<code>Cx</code> are classes while
* <code>Ix</code> are interfaces):
* <pre>
* C3 - I7 - I9
* | | /\
* | I8 I3 I4
* |
* C2 - I5 - I6
* |
* C1 - I1 - I2 - I4
* | |
* | I3
* Object
* </pre>
* When <code>message</code> is of type <code>C3</code> this hierarchy will be
* searched in the following order:
* <code>C3, I7, I8, I9, I3, I4, C2, I5, I6, C1, I1, I2, I3, I4, Object</code>.
* </p>
* <p>
* For efficiency searches will be cached. Calls to
* {@link #addReceivedMessageHandler(Class, MessageHandler)} and
* {@link #removeReceivedMessageHandler(Class)} clear this cache.
* </p>
*
* @author The Apache MINA Project (dev@mina.apache.org)
* @version $Rev: 603158 $, $Date: 2007-12-11 16:06:13 +0900 (화, 11 12월 2007) $
*/
public class DemuxingIoHandler extends IoHandlerAdapter {
private final Map<Class<?>, MessageHandler<?>> receivedMessageHandlerCache =
new ConcurrentHashMap<Class<?>, MessageHandler<?>>();
private final Map<Class<?>, MessageHandler<?>> receivedMessageHandlers =
new ConcurrentHashMap<Class<?>, MessageHandler<?>>();
private final Map<Class<?>, MessageHandler<?>> sentMessageHandlerCache =
new ConcurrentHashMap<Class<?>, MessageHandler<?>>();
private final Map<Class<?>, MessageHandler<?>> sentMessageHandlers =
new ConcurrentHashMap<Class<?>, MessageHandler<?>>();
private final Map<Class<?>, ExceptionHandler<?>> exceptionHandlerCache =
new ConcurrentHashMap<Class<?>, ExceptionHandler<?>>();
private final Map<Class<?>, ExceptionHandler<?>> exceptionHandlers =
new ConcurrentHashMap<Class<?>, ExceptionHandler<?>>();
/**
* Creates a new instance with no registered {@link MessageHandler}s.
*/
public DemuxingIoHandler() {
}
/**
* Registers a {@link MessageHandler} that handles the received messages of
* the specified <code>type</code>.
*
* @return the old handler if there is already a registered handler for
* the specified <tt>type</tt>. <tt>null</tt> otherwise.
*/
@SuppressWarnings("unchecked")
public <E> MessageHandler<? super E> addReceivedMessageHandler(Class<E> type,
MessageHandler<? super E> handler) {
receivedMessageHandlerCache.clear();
return (MessageHandler<? super E>) receivedMessageHandlers.put(type, handler);
}
/**
* Deregisters a {@link MessageHandler} that handles the received messages
* of the specified <code>type</code>.
*
* @return the removed handler if successfully removed. <tt>null</tt> otherwise.
*/
@SuppressWarnings("unchecked")
public <E> MessageHandler<? super E> removeReceivedMessageHandler(Class<E> type) {
receivedMessageHandlerCache.clear();
return (MessageHandler<? super E>) receivedMessageHandlers.remove(type);
}
/**
* Registers a {@link MessageHandler} that handles the sent messages of the
* specified <code>type</code>.
*
* @return the old handler if there is already a registered handler for
* the specified <tt>type</tt>. <tt>null</tt> otherwise.
*/
@SuppressWarnings("unchecked")
public <E> MessageHandler<? super E> addSentMessageHandler(Class<E> type,
MessageHandler<? super E> handler) {
sentMessageHandlerCache.clear();
return (MessageHandler<? super E>) sentMessageHandlers.put(type, handler);
}
/**
* Deregisters a {@link MessageHandler} that handles the sent messages of
* the specified <code>type</code>.
*
* @return the removed handler if successfully removed. <tt>null</tt> otherwise.
*/
@SuppressWarnings("unchecked")
public <E> MessageHandler<? super E> removeSentMessageHandler(Class<E> type) {
sentMessageHandlerCache.clear();
return (MessageHandler<? super E>) sentMessageHandlers.remove(type);
}
/**
* Registers a {@link MessageHandler} that receives the messages of
* the specified <code>type</code>.
*
* @return the old handler if there is already a registered handler for
* the specified <tt>type</tt>. <tt>null</tt> otherwise.
*/
@SuppressWarnings("unchecked")
public <E extends Throwable>
ExceptionHandler<? super E> addExceptionHandler(
Class<E> type, ExceptionHandler<? super E> handler) {
exceptionHandlerCache.clear();
return (ExceptionHandler<? super E>) exceptionHandlers.put(type, handler);
}
/**
* Deregisters a {@link MessageHandler} that receives the messages of
* the specified <code>type</code>.
*
* @return the removed handler if successfully removed. <tt>null</tt> otherwise.
*/
@SuppressWarnings("unchecked")
public <E extends Throwable> ExceptionHandler<? super E>
removeExceptionHandler(Class<E> type) {
exceptionHandlerCache.clear();
return (ExceptionHandler<? super E>) exceptionHandlers.remove(type);
}
/**
* Returns the {@link MessageHandler} which is registered to process
* the specified <code>type</code>.
*/
@SuppressWarnings("unchecked")
public <E> MessageHandler<? super E> getMessageHandler(Class<E> type) {
return (MessageHandler<? super E>) receivedMessageHandlers.get(type);
}
/**
* Returns the {@link Map} which contains all messageType-{@link MessageHandler}
* pairs registered to this handler for received messages.
*/
public Map<Class<?>, MessageHandler<?>> getReceivedMessageHandlerMap() {
return Collections.unmodifiableMap(receivedMessageHandlers);
}
/**
* Returns the {@link Map} which contains all messageType-{@link MessageHandler}
* pairs registered to this handler for sent messages.
*/
public Map<Class<?>, MessageHandler<?>> getSentMessageHandlerMap() {
return Collections.unmodifiableMap(sentMessageHandlers);
}
/**
* Returns the {@link Map} which contains all messageType-{@link MessageHandler}
* pairs registered to this handler.
*/
public Map<Class<?>, ExceptionHandler<?>> getExceptionHandlerMap() {
return Collections.unmodifiableMap(exceptionHandlers);
}
/**
* Forwards the received events into the appropriate {@link MessageHandler}
* which is registered by {@link #addReceivedMessageHandler(Class, MessageHandler)}.
*/
@Override
public void messageReceived(IoSession session, Object message)
throws Exception {
MessageHandler<Object> handler = findReceivedMessageHandler(message.getClass());
if (handler != null) {
handler.handleMessage(session, message);
} else {
throw new UnknownMessageTypeException(
"No message handler found for message type: " +
message.getClass().getSimpleName());
}
}
@Override
public void messageSent(IoSession session, Object message) throws Exception {
MessageHandler<Object> handler = findSentMessageHandler(message.getClass());
if (handler != null) {
handler.handleMessage(session, message);
} else {
throw new UnknownMessageTypeException(
"No handler found for message type: " +
message.getClass().getSimpleName());
}
}
@Override
public void exceptionCaught(IoSession session, Throwable cause) throws Exception {
ExceptionHandler<Throwable> handler = findExceptionHandler(cause.getClass());
if (handler != null) {
handler.exceptionCaught(session, cause);
} else {
throw new UnknownMessageTypeException(
"No handler found for exception type: " +
cause.getClass().getSimpleName());
}
}
protected MessageHandler<Object> findReceivedMessageHandler(Class<?> type) {
return findReceivedMessageHandler(type, null);
}
protected MessageHandler<Object> findSentMessageHandler(Class<?> type) {
return findSentMessageHandler(type, null);
}
protected ExceptionHandler<Throwable> findExceptionHandler(Class<? extends Throwable> type) {
return findExceptionHandler(type, null);
}
@SuppressWarnings("unchecked")
private MessageHandler<Object> findReceivedMessageHandler(
Class type, Set<Class> triedClasses) {
return (MessageHandler<Object>) findHandler(
receivedMessageHandlers, receivedMessageHandlerCache, type, triedClasses);
}
@SuppressWarnings("unchecked")
private MessageHandler<Object> findSentMessageHandler(
Class type, Set<Class> triedClasses) {
return (MessageHandler<Object>) findHandler(
sentMessageHandlers, sentMessageHandlerCache, type, triedClasses);
}
@SuppressWarnings("unchecked")
private ExceptionHandler<Throwable> findExceptionHandler(
Class type, Set<Class> triedClasses) {
return (ExceptionHandler<Throwable>) findHandler(
exceptionHandlers, exceptionHandlerCache, type, triedClasses);
}
@SuppressWarnings("unchecked")
private Object findHandler(
Map handlers, Map handlerCache,
Class type, Set<Class> triedClasses) {
Object handler = null;
if (triedClasses != null && triedClasses.contains(type)) {
return null;
}
/*
* Try the cache first.
*/
handler = handlerCache.get(type);
if (handler != null) {
return handler;
}
/*
* Try the registered handlers for an immediate match.
*/
handler = handlers.get(type);
if (handler == null) {
/*
* No immediate match could be found. Search the type's interfaces.
*/
if (triedClasses == null) {
triedClasses = new IdentityHashSet<Class>();
}
triedClasses.add(type);
Class[] interfaces = type.getInterfaces();
for (Class element : interfaces) {
handler = findHandler(handlers, handlerCache, element, triedClasses);
if (handler != null) {
break;
}
}
}
if (handler == null) {
/*
* No match in type's interfaces could be found. Search the
* superclass.
*/
Class superclass = type.getSuperclass();
if (superclass != null) {
handler = findHandler(handlers, handlerCache, superclass, null);
}
}
/*
* Make sure the handler is added to the cache. By updating the cache
* here all the types (superclasses and interfaces) in the path which
* led to a match will be cached along with the immediate message type.
*/
if (handler != null) {
handlerCache.put(type, handler);
}
return handler;
}
}