    001    // Copyright 2007, 2011 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    // http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.internal.services;
    016
    017    import java.lang.reflect.Method;
    018
    019    import org.apache.tapestry5.ioc.services.Builtin;
    020    import org.apache.tapestry5.ioc.services.PlasticProxyFactory;
    021    import org.apache.tapestry5.plastic.ClassInstantiator;
    022    import org.apache.tapestry5.plastic.MethodAdvice;
    023    import org.apache.tapestry5.plastic.MethodInvocation;
    024    import org.apache.tapestry5.plastic.PlasticClass;
    025    import org.apache.tapestry5.plastic.PlasticClassTransformer;
    026    import org.apache.tapestry5.plastic.PlasticMethod;
    027    import org.apache.tapestry5.plastic.PlasticUtils;
    028    import org.apache.tapestry5.services.Environment;
    029    import org.apache.tapestry5.services.EnvironmentalShadowBuilder;
    030
    031    public class EnvironmentalShadowBuilderImpl implements EnvironmentalShadowBuilder
    032    {
    033        private final PlasticProxyFactory proxyFactory;
    034
    035        private final Environment environment;
    036
    037        /**
    038         * Construct using the default builtin factory, not the component layer version.
    039         */
    040        public EnvironmentalShadowBuilderImpl(@Builtin
    041        PlasticProxyFactory proxyFactory,
    042
    043        Environment environment)
    044        {
    045            this.proxyFactory = proxyFactory;
    046            this.environment = environment;
    047        }
    048
    049        public <T> T build(final Class<T> serviceType)
    050        {
    051            ClassInstantiator<T> instantiator = proxyFactory.createProxy(serviceType, new PlasticClassTransformer()
    052            {
    053                public void transform(PlasticClass plasticClass)
    054                {
    055                    PlasticMethod delegateMethod = plasticClass.introducePrivateMethod(
    056                            PlasticUtils.toTypeName(serviceType), "delegate", null, null);
    057
    058                    delegateMethod.addAdvice(new MethodAdvice()
    059                    {
    060                        public void advise(MethodInvocation invocation)
    061                        {
    062                            invocation.setReturnValue(environment.peekRequired(serviceType));
    063                        }
    064                    });
    065
    066                    for (Method method : serviceType.getMethods())
    067                    {
    068                        plasticClass.introduceMethod(method).delegateTo(delegateMethod);
    069                    }
    070
    071                    plasticClass.addToString(String.format("<EnvironmentalProxy for %s>", serviceType.getName()));
    072                }
    073            });
    074
    075            return instantiator.newInstance();
    076        }
    077    }