/***
* Copyright (c) 2009 Caelum - www.caelum.com.br/opensource All rights reserved.
*
* 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 br.com.caelum.vraptor.proxy;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import javassist.util.proxy.MethodFilter;
import javassist.util.proxy.MethodHandler;
import javassist.util.proxy.ProxyFactory;
import javassist.util.proxy.ProxyObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import br.com.caelum.vraptor.ioc.ApplicationScoped;
/**
* Javassist implementation for {@link Proxifier}.
*
* @author Otávio Scherer Garcia
* @since 3.3.1
*/
@ApplicationScoped
public class JavassistProxifier
implements Proxifier {
private static final Logger logger = LoggerFactory.getLogger(JavassistProxifier.class);
/**
* Methods like toString and finalize will be ignored.
*/
private static final List<Method> OBJECT_METHODS = Arrays.asList(Object.class.getDeclaredMethods());
/**
* Do not proxy these methods.
*/
private static final MethodFilter IGNORE_BRIDGE_AND_OBJECT_METHODS = new MethodFilter() {
public boolean isHandled(Method method) {
return !method.isBridge() && !OBJECT_METHODS.contains(method);
}
};
private final InstanceCreator instanceCreator;
public JavassistProxifier(InstanceCreator instanceCreator) {
this.instanceCreator = instanceCreator;
}
public <T> T proxify(Class<T> type, MethodInvocation<? super T> handler) {
final ProxyFactory factory = new ProxyFactory();
factory.setFilter(IGNORE_BRIDGE_AND_OBJECT_METHODS);
if (type.isInterface()) {
factory.setInterfaces(new Class[] { type });
} else {
factory.setSuperclass(type);
}
Class<?> proxyClass = factory.createClass();
Object proxyInstance = instanceCreator.instanceFor(proxyClass);
setHandler(proxyInstance, handler);
logger.debug("a proxy for {} is created as {}", type, proxyClass);
return type.cast(proxyInstance);
}
public boolean isProxy(Object o) {
return o != null && ProxyObject.class.isAssignableFrom(o.getClass());
}
private <T> void setHandler(Object proxyInstance, final MethodInvocation<? super T> handler) {
ProxyObject proxyObject = (ProxyObject) proxyInstance;
proxyObject.setHandler(new MethodHandler() {
public Object invoke(final Object self, final Method thisMethod, final Method proceed, Object[] args)
throws Throwable {
return handler.intercept((T) self, thisMethod, args, new SuperMethod() {
public Object invoke(Object proxy, Object[] args) {
try {
return proceed.invoke(proxy, args);
} catch (Throwable throwable) {
throw new ProxyInvocationException(throwable);
}
}
});
}
});
}
}