| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| |
| /** |
| * @author Boris V. Kuznetsov |
| * @version $Revision$ |
| */ |
| |
| package org.apache.harmony.security.fortress; |
| |
| import java.security.NoSuchAlgorithmException; |
| import java.security.Provider; |
| import java.util.Locale; |
| |
| |
| /** |
| * This class implements common functionality for Provider supplied |
| * classes. The usage pattern is to allocate static Engine instance |
| * per service type and synchronize on that instance during calls to |
| * {@code getInstance} and retreival of the selected {@code Provider} |
| * and Service Provider Interface (SPI) results. Retreiving the |
| * results with {@code getProvider} and {@code getSpi} sets the |
| * internal {@code Engine} values to null to prevent memory leaks. |
| * |
| * <p> |
| * |
| * For example: <pre> {@code |
| * public class Foo { |
| * |
| * private static final Engine ENGINE = new Engine("Foo"); |
| * |
| * private final FooSpi spi; |
| * private final Provider provider; |
| * private final String algorithm; |
| * |
| * protected Foo(FooSpi spi, |
| * Provider provider, |
| * String algorithm) { |
| * this.spi = spi; |
| * this.provider = provider; |
| * this.algorithm = algorithm; |
| * } |
| * |
| * public static Foo getInstance(String algorithm) { |
| * Engine.SpiAndProvider sap = ENGINE.getInstance(algorithm, null); |
| * return new Foo((FooSpi) sap.spi, sap.provider, algorithm); |
| * } |
| * |
| * public static Foo getInstance(String algorithm, Provider provider) { |
| * Object spi = ENGINE.getInstance(algorithm, provider, null); |
| * return new Foo((FooSpi) spi, provider, algorithm); |
| * } |
| * |
| * ... |
| * |
| * }</pre> |
| */ |
| public class Engine { |
| |
| /** |
| * Access to package visible api in java.security |
| */ |
| public static SecurityAccess door; |
| |
| /** |
| * Service name such as Cipher or SSLContext |
| */ |
| private final String serviceName; |
| |
| /** |
| * Previous result for getInstance(String, Object) optimization. |
| * Only this non-Provider version of getInstance is optimized |
| * since the the Provider version does not require an expensive |
| * Services.getService call. |
| */ |
| private volatile ServiceCacheEntry serviceCache; |
| |
| private static final class ServiceCacheEntry { |
| /** used to test for cache hit */ |
| private final String algorithm; |
| /** used to test for cache validity */ |
| private final int refreshNumber; |
| /** cached result */ |
| private final Provider.Service service; |
| |
| private ServiceCacheEntry(String algorithm, |
| int refreshNumber, |
| Provider.Service service) { |
| this.algorithm = algorithm; |
| this.refreshNumber = refreshNumber; |
| this.service = service; |
| } |
| } |
| |
| public static final class SpiAndProvider { |
| public final Object spi; |
| public final Provider provider; |
| private SpiAndProvider(Object spi, Provider provider) { |
| this.spi = spi; |
| this.provider = provider; |
| } |
| } |
| |
| /** |
| * Creates a Engine object |
| * |
| * @param service |
| */ |
| public Engine(String service) { |
| this.serviceName = service; |
| } |
| |
| /** |
| * Finds the appropriate service implementation and returns an |
| * {@code SpiAndProvider} instance containing a reference to SPI |
| * and its {@code Provider} |
| */ |
| public SpiAndProvider getInstance(String algorithm, Object param) |
| throws NoSuchAlgorithmException { |
| if (algorithm == null) { |
| throw new NoSuchAlgorithmException("Null algorithm name"); |
| } |
| Services.refresh(); |
| Provider.Service service; |
| ServiceCacheEntry cacheEntry = this.serviceCache; |
| if (cacheEntry != null |
| && cacheEntry.algorithm.equalsIgnoreCase(algorithm) |
| && Services.refreshNumber == cacheEntry.refreshNumber) { |
| service = cacheEntry.service; |
| } else { |
| if (Services.isEmpty()) { |
| throw notFound(serviceName, algorithm); |
| } |
| String name = this.serviceName + "." + algorithm.toUpperCase(Locale.US); |
| service = Services.getService(name); |
| if (service == null) { |
| throw notFound(serviceName, algorithm); |
| } |
| this.serviceCache = new ServiceCacheEntry(algorithm, Services.refreshNumber, service); |
| } |
| return new SpiAndProvider(service.newInstance(param), service.getProvider()); |
| } |
| |
| /** |
| * Finds the appropriate service implementation and returns and |
| * instance of the class that implements corresponding Service |
| * Provider Interface. |
| */ |
| public Object getInstance(String algorithm, Provider provider, Object param) |
| throws NoSuchAlgorithmException { |
| if (algorithm == null) { |
| throw new NoSuchAlgorithmException("algorithm == null"); |
| } |
| Provider.Service service = provider.getService(serviceName, algorithm); |
| if (service == null) { |
| throw notFound(serviceName, algorithm); |
| } |
| return service.newInstance(param); |
| } |
| |
| private NoSuchAlgorithmException notFound(String serviceName, String algorithm) |
| throws NoSuchAlgorithmException { |
| throw new NoSuchAlgorithmException(serviceName + " " + algorithm |
| + " implementation not found"); |
| } |
| } |