/*
* Copyright 2010 Google Inc.
*
* 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 com.google.gwt.autobean.server;
import com.google.gwt.autobean.shared.AutoBean;
import com.google.gwt.autobean.shared.AutoBeanFactory;
import com.google.gwt.autobean.shared.AutoBeanFactory.Category;
import com.google.gwt.autobean.shared.AutoBeanFactory.NoWrap;
import com.google.gwt.autobean.shared.impl.EnumMap;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
/**
* Generates JVM-compatible implementations of AutoBeanFactory and AutoBean
* types.
* <p>
* This implementation is written assuming that the AutoBeanFactory and
* associated declarations will validate if compiled and used with the
* AutoBeanFactoyModel.
*/
public class AutoBeanFactoryMagic {
/*
* NB: This implementation is excessively dynamic, however the inability to
* create a TypeOracle fram a ClassLoader prevents re-using the existing model
* code. If the model code could be reused, it would be straightforward to
* simply generate implementations of the various interfaces.
*/
private static final AutoBeanFactory EMPTY = create(AutoBeanFactory.class);
/**
* Create an instance of an AutoBeanFactory.
*
* @param <F> the factory type
* @param clazz the Class representing the factory interface
* @return an instance of the AutoBeanFactory
*/
public static <F extends AutoBeanFactory> F create(Class<F> clazz) {
Configuration.Builder builder = new Configuration.Builder();
Category cat = clazz.getAnnotation(Category.class);
if (cat != null) {
builder.setCategories(cat.value());
}
NoWrap noWrap = clazz.getAnnotation(NoWrap.class);
if (noWrap != null) {
builder.setNoWrap(noWrap.value());
}
return makeProxy(clazz, new FactoryHandler(builder.build()), EnumMap.class);
}
/**
* Create an instance of an AutoBean directly.
*
* @param <T> the interface type implemented by the AutoBean
* @param clazz the interface type implemented by the AutoBean
* @return an instance of an AutoBean
*/
public static <T> AutoBean<T> createBean(Class<T> clazz,
Configuration configuration) {
return new ProxyAutoBean<T>(EMPTY, clazz, configuration);
}
/**
* Utility method to crete a new {@link Proxy} instance.
*
* @param <T> the interface type to be implemented by the Proxy
* @param intf the Class representing the interface type
* @param handler the implementation of the interface
* @param extraInterfaces additional interface types the Proxy should
* implement
* @return a Proxy instance
*/
static <T> T makeProxy(Class<T> intf, InvocationHandler handler,
Class<?>... extraInterfaces) {
Class<?>[] intfs;
if (extraInterfaces == null) {
intfs = new Class<?>[] {intf};
} else {
intfs = new Class<?>[extraInterfaces.length + 1];
intfs[0] = intf;
System.arraycopy(extraInterfaces, 0, intfs, 1, extraInterfaces.length);
}
return intf.cast(Proxy.newProxyInstance(intf.getClassLoader(), intfs,
handler));
}
}