/*
* 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.statemachine;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import org.apache.mina.statemachine.context.SingletonStateContextLookup;
import org.apache.mina.statemachine.context.StateContext;
import org.apache.mina.statemachine.context.StateContextLookup;
import org.apache.mina.statemachine.event.DefaultEventFactory;
import org.apache.mina.statemachine.event.Event;
import org.apache.mina.statemachine.event.EventArgumentsInterceptor;
import org.apache.mina.statemachine.event.EventFactory;
import org.apache.mina.statemachine.event.UnhandledEventException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Used to create proxies which will forward all method calls on them to a
* {@link StateMachine}.
*
* @author The Apache MINA Project (dev@mina.apache.org)
* @version $Rev: 664321 $, $Date: 2008-06-07 13:19:55 +0200 (Sat, 07 Jun 2008) $
*/
public class StateMachineProxyBuilder {
private static final Logger log = LoggerFactory
.getLogger(StateMachineProxyBuilder.class);
private static final Object[] EMPTY_ARGUMENTS = new Object[0];
private StateContextLookup contextLookup = new SingletonStateContextLookup();
private EventFactory eventFactory = new DefaultEventFactory();
private EventArgumentsInterceptor interceptor = null;
private boolean ignoreUnhandledEvents = false;
private boolean ignoreStateContextLookupFailure = false;
private String name = null;
/*
* The classloader to use. Iif null we will use the current thread's
* context classloader.
*/
private ClassLoader defaultCl = null;
public StateMachineProxyBuilder() {
}
/**
* Sets the name of the proxy created by this builder. This will be used
* by the proxies <code>toString()</code> method. If not specified a default
* auto generated name will be used.
*
* @param name the name.
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setName(String name) {
this.name = name;
return this;
}
/**
* Sets the {@link StateContextLookup} to be used. The default is to use
* a {@link SingletonStateContextLookup}.
*
* @param contextLookup the {@link StateContextLookup} to use.
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setStateContextLookup(
StateContextLookup contextLookup) {
this.contextLookup = contextLookup;
return this;
}
/**
* Sets the {@link EventFactory} to be used. The default is to use a
* {@link DefaultEventFactory}.
*
* @param eventFactory the {@link EventFactory} to use.
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setEventFactory(EventFactory eventFactory) {
this.eventFactory = eventFactory;
return this;
}
/**
* Sets the {@link EventArgumentsInterceptor} to be used. By default no
* {@link EventArgumentsInterceptor} will be used.
*
* @param interceptor the {@link EventArgumentsInterceptor} to use.
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setEventArgumentsInterceptor(
EventArgumentsInterceptor interceptor) {
this.interceptor = interceptor;
return this;
}
/**
* Sets whether events which have no handler in the current state will raise
* an exception or be silently ignored. The default is to raise an
* exception.
*
* @param b <code>true</code> to ignore context lookup failures.
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setIgnoreUnhandledEvents(boolean b) {
this.ignoreUnhandledEvents = b;
return this;
}
/**
* Sets whether the failure to lookup a {@link StateContext} corresponding
* to a method call on the proxy produced by this builder will raise an
* exception or be silently ignored. The default is to raise an exception.
*
* @param b <code>true</code> to ignore context lookup failures.
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setIgnoreStateContextLookupFailure(boolean b) {
this.ignoreStateContextLookupFailure = b;
return this;
}
/**
* Sets the class loader to use for instantiating proxies. The default is
* to use the current threads context {@link ClassLoader} as returned by
* {@link Thread#getContextClassLoader()}.
*
* @param cl the class loader
* @return this {@link StateMachineProxyBuilder} for method chaining.
*/
public StateMachineProxyBuilder setClassLoader(ClassLoader cl) {
this.defaultCl = cl;
return this;
}
/**
* Creates a proxy for the specified interface and which uses the specified
* {@link StateMachine}.
*
* @param iface the interface the proxy will implement.
* @param sm the {@link StateMachine} which will receive the events
* generated by the method calls on the proxy.
* @return the proxy object.
*/
@SuppressWarnings("unchecked")
public <T> T create(Class<T> iface, StateMachine sm) {
return (T) create(new Class[] { iface }, sm);
}
/**
* Creates a proxy for the specified interfaces and which uses the specified
* {@link StateMachine}.
*
* @param ifaces the interfaces the proxy will implement.
* @param sm the {@link StateMachine} which will receive the events
* generated by the method calls on the proxy.
* @return the proxy object.
*/
public Object create(Class<?>[] ifaces, StateMachine sm) {
ClassLoader cl = defaultCl;
if (cl == null) {
cl = Thread.currentThread().getContextClassLoader();
}
InvocationHandler handler = new MethodInvocationHandler(sm,
contextLookup, interceptor, eventFactory,
ignoreUnhandledEvents, ignoreStateContextLookupFailure, name);
return Proxy.newProxyInstance(cl, ifaces, handler);
}
private static class MethodInvocationHandler implements InvocationHandler {
private final StateMachine sm;
private final StateContextLookup contextLookup;
private final EventArgumentsInterceptor interceptor;
private final EventFactory eventFactory;
private final boolean ignoreUnhandledEvents;
private final boolean ignoreStateContextLookupFailure;
private final String name;
public MethodInvocationHandler(StateMachine sm, StateContextLookup contextLookup,
EventArgumentsInterceptor interceptor, EventFactory eventFactory,
boolean ignoreUnhandledEvents, boolean ignoreStateContextLookupFailure,
String name) {
this.contextLookup = contextLookup;
this.sm = sm;
this.interceptor = interceptor;
this.eventFactory = eventFactory;
this.ignoreUnhandledEvents = ignoreUnhandledEvents;
this.ignoreStateContextLookupFailure = ignoreStateContextLookupFailure;
this.name = name;
}
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if ("hashCode".equals(method.getName()) && args == null) {
return new Integer(System.identityHashCode(proxy));
}
if ("equals".equals(method.getName()) && args.length == 1) {
return Boolean.valueOf(proxy == args[0]);
}
if ("toString".equals(method.getName()) && args == null) {
return (name != null ? name : proxy.getClass().getName()) + "@"
+ Integer.toHexString(System.identityHashCode(proxy));
}
if (log.isDebugEnabled()) {
log.debug("Method invoked: " + method);
}
args = args == null ? EMPTY_ARGUMENTS : args;
if (interceptor != null) {
args = interceptor.modify(args);
}
StateContext context = contextLookup.lookup(args);
if (context == null) {
if (ignoreStateContextLookupFailure) {
return null;
}
throw new IllegalStateException("Cannot determine state "
+ "context for method invocation: " + method);
}
Event event = eventFactory.create(context, method, args);
try {
sm.handle(event);
} catch (UnhandledEventException uee) {
if (!ignoreUnhandledEvents) {
throw uee;
}
}
return null;
}
}
}