001 /* 002 * Licensed under the Apache License, Version 2.0 (the "License"); 003 * you may not use this file except in compliance with the License. 004 * You may obtain a copy of the License at 005 * 006 * http://www.apache.org/licenses/LICENSE-2.0 007 * 008 * Unless required by applicable law or agreed to in writing, software 009 * distributed under the License is distributed on an "AS IS" BASIS, 010 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 011 * See the License for the specific language governing permissions and 012 * limitations under the License. 013 */ 014 package org.apache.commons.classscan.util; 015 016 import java.util.ArrayList; 017 import java.util.Collection; 018 import java.util.Collections; 019 import java.util.Iterator; 020 021 /** 022 * A cache of service providers. 023 * 024 * @param <T> The interface of the service provider 025 */ 026 public class FactoryCache<T> implements Iterable<T> { 027 028 final private Collection<T> readOnly; 029 030 /** 031 * Find service providers available to the given classLoader 032 * 033 * @param serviceProvider The interface of the service provider 034 * @param classLoader The ClassLoader to load the service provider instances 035 */ 036 public FactoryCache(Class<T> serviceProvider, ClassLoader classLoader) { 037 038 final ArrayList<T> instances = new ArrayList<T>(); 039 040 new ServiceVisitor<T>() { 041 @Override 042 protected boolean visit(T factory) { 043 instances.add(factory); 044 return true; 045 } 046 }.visitProviders(serviceProvider, classLoader); 047 048 instances.trimToSize(); 049 readOnly = Collections.unmodifiableCollection(instances); 050 } 051 052 @Override 053 public Iterator<T> iterator() { 054 return readOnly.iterator(); 055 } 056 }