/*
* Demoiselle Framework
* Copyright (C) 2010 SERPRO
* ----------------------------------------------------------------------------
* This file is part of Demoiselle Framework.
*
* Demoiselle Framework is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License version 3
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License version 3
* along with this program; if not, see <http://www.gnu.org/licenses/>
* or write to the Free Software Foundation, Inc., 51 Franklin Street,
* Fifth Floor, Boston, MA 02110-1301, USA.
* ----------------------------------------------------------------------------
* Este arquivo é parte do Framework Demoiselle.
*
* O Framework Demoiselle é um software livre; você pode redistribuí-lo e/ou
* modificá-lo dentro dos termos da GNU LGPL versão 3 como publicada pela Fundação
* do Software Livre (FSF).
*
* Este programa é distribuído na esperança que possa ser útil, mas SEM NENHUMA
* GARANTIA; sem uma garantia implícita de ADEQUAÇÃO a qualquer MERCADO ou
* APLICAÇÃO EM PARTICULAR. Veja a Licença Pública Geral GNU/LGPL em português
* para maiores detalhes.
*
* Você deve ter recebido uma cópia da GNU LGPL versão 3, sob o título
* "LICENCA.txt", junto com esse programa. Se não, acesse <http://www.gnu.org/licenses/>
* ou escreva para a Fundação do Software Livre (FSF) Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02111-1301, USA.
*/
package br.gov.frameworkdemoiselle.exception;
import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext;
import org.slf4j.Logger;
import br.gov.frameworkdemoiselle.DemoiselleException;
import br.gov.frameworkdemoiselle.stereotype.Controller;
import br.gov.frameworkdemoiselle.util.Beans;
import br.gov.frameworkdemoiselle.util.NameQualifier;
import br.gov.frameworkdemoiselle.util.ResourceBundle;
/**
* <p>
* Intercepts some thrown exceptions, and calls the appropriate method. These interceptor works only in
* classes annotated with <b>@Contoller</b>. Above we discribe which kind of exception is intercepted and
* what is an appropriate method.
* <p>
* To be interceptable, the thrown exception must be from a type which is annotated with
* <b>@ApplicationException</b>.
* <p>
* An appropriate method must be annotated with <b>@ExceptionHandler</b>, and receive as parameter some
* exception that could be thrown for it's class (which have to be annotated with <b>@ApplicationException</b>).
* So, when this method is called, it's receive the thrown exception as parameter. In the same class shouldn't
* be more than one method annotated with <b>@ExceptionHandler</b> and receiving the same type of exception.
* <p>
* <p>
* The examples below shows how these interceptor works:
* <p>
*
* <blockquote>
*
* <pre>
* @ApplicationException
* public class CustomException extends RuntimeException {
* }
*
* @Controller
* public class CustomExceptionHandler {
*
* public void throwException() {
* throw new CustomException();
* }
*
* @ExceptionHandler
* public void handler(CustomException exception) {
* ...
* }
*
* }
* </pre>
* </blockquote>
*
* <p>
* When the method <b>throwException</b> throw a <b>CustomException</b>, once CustomException is annotated
* with @ApplicationException and CustomExceptionHandle is annotated with @Controller, the interceptor will
* looking for some method (in CustomExceptionHandle) annotated with @ExceptionHandle and that receive a
* CustomException as parameter to call. In the case shown, the method <b>handler</b> is called when a
* <b>CustomException</b> is thrown.
* <p>
*
* @author SERPRO
*/
@Interceptor
@Controller
public class ExceptionHandlerInterceptor implements Serializable {
private static final long serialVersionUID = 1L;
private static transient ResourceBundle bundle;
private static transient Logger logger;
private final Map<Class<?>, Map<Class<?>, Method>> cache = new HashMap<Class<?>, Map<Class<?>, Method>>();
private boolean handleException(final Exception cause, final Object target) throws Exception {
getLogger().info(getBundle().getString("handling-exception", cause.getClass().getCanonicalName()));
boolean handled = false;
Class<?> type = target.getClass();
if (!isLoaded(type)) {
loadHandlers(type);
}
Method handler = getMethod(type, cause.getClass());
if (handler != null) {
invoke(handler, target, cause);
handled = true;
}
return handled;
}
/**
* If there is an handler in the current class or superClass for the expected exception, then this method will be
* returned; Else returns null;
*
* @param type
* @param causeClass
* @return
*/
private Method getMethod(final Class<?> type, final Class<?> causeClass) {
Method handler = null;
Map<Class<?>, Method> map = cache.get(type);
if (map != null && Throwable.class.isAssignableFrom(causeClass)) {
if (map.containsKey(causeClass)) {
handler = map.get(causeClass);
} else {
handler = getMethod(type, causeClass.getSuperclass());
}
}
return handler;
}
/**
* Create an map of Exception Handler for this class and put it on the cache.
*
* @param type
*/
private void loadHandlers(final Class<?> type) {
Map<Class<?>, Method> mapHandlers = new HashMap<Class<?>, Method>();
List<Method> methods = new ArrayList<Method>();
Class<?> tempType = type;
while (tempType != null) {
methods.addAll(Arrays.asList(tempType.getMethods()));
tempType = tempType.getSuperclass();
}
for (Method method : methods) {
if (method.isAnnotationPresent(ExceptionHandler.class)) {
validateHandler(method);
mapHandlers.put(method.getParameterTypes()[0], method);
}
}
cache.put(type, mapHandlers);
}
/**
* Verify the method for compliance with an handler. It must be: public, single parameter, parameter type must be
* assigned from Exception
*
* @param method
*/
private void validateHandler(final Method method) {
if (method.getParameterTypes().length != 1) {
throw new DemoiselleException(getBundle().getString("must-declare-one-single-parameter",
method.toGenericString()));
}
}
/**
* Indicates if this class is already loaded in cache control.
*
* @param type
* @return
*/
private boolean isLoaded(final Class<?> type) {
return cache.containsKey(type);
}
private void invoke(final Method method, final Object object, final Exception param) throws Exception {
boolean accessible = method.isAccessible();
method.setAccessible(true);
try {
method.invoke(object, param);
} catch (InvocationTargetException cause) {
Throwable targetTrowable = cause.getTargetException();
if (targetTrowable instanceof Exception) {
throw (Exception) targetTrowable;
} else {
throw new Exception(targetTrowable);
}
}
method.setAccessible(accessible);
}
@AroundInvoke
public Object manage(final InvocationContext ic) throws Exception {
Object result = null;
Object target = ic.getTarget();
try {
result = ic.proceed();
} catch (Exception cause) {
if (!handleException(cause, target)) {
throw cause;
}
}
return result;
}
private static ResourceBundle getBundle() {
if (bundle == null) {
bundle = Beans.getReference(ResourceBundle.class, new NameQualifier("demoiselle-core-bundle"));
}
return bundle;
}
private static Logger getLogger() {
if (logger == null) {
logger = Beans.getReference(Logger.class, new NameQualifier(ExceptionHandlerInterceptor.class.getName()));
}
return logger;
}
}