/*
 * Copyright 2005-2010 the original author or authors.
 * 
 * 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 org.wamblee.inject;

import java.util.ServiceLoader;


/**
 * Singleton injector access. This should be used as main entry point for
 * injection. A different {@link InjectorFactory} can be plugged in for testing.
 * 
 * Given the following class: 
 * <pre> 
 * class Pojo {
 *   &#064;EJB
 *   private Service service; 
 *   
 *   ...
 * }
 * </pre>
 * injecting the EJB into a POJO using Contexts and Dependency Injection is accomplished as follows: 
 * <pre>
 *   Pojo pojo = new Pojo(); 
 *   SimpleInjector injector = new SimpleInjector(new CdiInjectorFactory()); 
 *   injector.inject(pojo);
 * </pre>
 * 
 * Note that it is recommended to cache the injector because the injector does caching 
 * of the types that it injects into. Caching the injector makes sure that a class is not
 * analysed again for annotation every time injection is used. 
 * 
 * The {@link InjectorFactory} to be used can also be found using a {@link ServiceLoader} discovery
 * mechanism as provided by {@link InjectorFactoryBuilder}. 
 * 
 * @author Erik Brakkee
 */
public class SimpleInjector {

    private InjectorCache cache;

    /**
     * Constructs the injector. 
     * @param aFactory Factory to use. 
     */
    public SimpleInjector(InjectorFactory aFactory) { 
        cache = new InjectorCache(aFactory);
    }
    
    /**
     * Injects into a given object.
     * 
     * @param aObject
     *            Object to inject into.
     */
    public void inject(Object aObject) {
        cache.getInjector(aObject.getClass()).inject(aObject);
    }
}