From 96d22b123242f42c216e90555d07656900e6ae6c Mon Sep 17 00:00:00 2001 From: Michael Koch Date: Wed, 21 Apr 2004 08:20:31 +0000 Subject: ServiceFactory.java, [...]: New files. 2004-04-21 Michael Koch * gnu/classpath/ServiceFactory.java, gnu/classpath/ServiceProviderLoadingAction.java, javax/imageio/ImageReader.java, javax/imageio/ImageTranscoder.java, javax/imageio/ImageWriter.java, javax/imageio/package.html, javax/imageio/spi/IIOServiceProvider.java, javax/imageio/spi/ImageInputStreamSpi.java, javax/imageio/spi/ImageOutputStreamSpi.java, javax/imageio/spi/ImageReaderWriterSpi.java, javax/imageio/spi/ImageTranscoderSpi.java, javax/imageio/spi/RegisterableService.java, javax/imageio/spi/ServiceRegistry.java, javax/imageio/spi/package.html, javax/imageio/stream/IIOByteBuffer.java, javax/imageio/stream/ImageInputStream.java, javax/imageio/stream/ImageOutputStream.java, javax/imageio/stream/package.html: New files. * Makefile.am (ordinary_java_source_files): Added gnu/classpath/ServiceFactory.java and gnu/classpath/ServiceProviderLoadingAction.java. (javax_source_files): Added javax/imageio/ImageReader.java, javax/imageio/ImageTranscoder.java, javax/imageio/ImageWriter.java, javax/imageio/spi/IIOServiceProvider.java, javax/imageio/spi/ImageInputStreamSpi.java, javax/imageio/spi/ImageOutputStreamSpi.java, javax/imageio/spi/ImageReaderWriterSpi.java, javax/imageio/spi/ImageTranscoderSpi.java, javax/imageio/spi/RegisterableService.java, javax/imageio/spi/ServiceRegistry.java, javax/imageio/stream/IIOByteBuffer.java, javax/imageio/stream/ImageInputStream.java and javax/imageio/stream/ImageOutputStream.java. * Makefile.in: Regenerated. From-SVN: r80951 --- .../classpath/ServiceProviderLoadingAction.java | 149 +++++++++++++++++++++ 1 file changed, 149 insertions(+) create mode 100644 libjava/gnu/classpath/ServiceProviderLoadingAction.java (limited to 'libjava/gnu/classpath/ServiceProviderLoadingAction.java') diff --git a/libjava/gnu/classpath/ServiceProviderLoadingAction.java b/libjava/gnu/classpath/ServiceProviderLoadingAction.java new file mode 100644 index 0000000..4832c97 --- /dev/null +++ b/libjava/gnu/classpath/ServiceProviderLoadingAction.java @@ -0,0 +1,149 @@ +/* ServiceProviderLoadingAction.java -- Action for loading plug-in services. + Copyright (C) 2004 Free Software Foundation + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA +02111-1307 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.classpath; + +import java.security.PrivilegedExceptionAction; + +/** + * A privileged action for creating a new instance of a service + * provider. + * + *

Class loading and instantiation is encapsulated in a + * PriviledgedAction in order to restrict the loaded + * service providers to the {@link java.security.AccessControlContext} + * that was active when {@link + * gnu.classpath.ServiceFactory#lookupProviders} was called, even + * though the actual loading is delayed to the time when the provider + * is actually needed. + * + * @author Sascha Brawer + */ +final class ServiceProviderLoadingAction + implements PrivilegedExceptionAction +{ + /** + * The interface to which the loaded service provider implementation + * must conform. Usually, this is a Java interface type, but it + * might also be an abstract class or even a concrete class. + */ + private final Class spi; + + + /** + * The fully qualified name of the class that gets loaded when + * this action is executed. + */ + private final String providerName; + + + /** + * The ClassLoader that gets used for loading the service provider + * class. + */ + private final ClassLoader loader; + + + /** + * Constructs a privileged action for loading a service provider. + * + * @param spi the interface to which the loaded service provider + * implementation must conform. Usually, this is a Java interface + * type, but it might also be an abstract class or even a concrete + * superclass. + * + * @param providerName the fully qualified name of the class that + * gets loaded when this action is executed. + * + * @param loader the ClassLoader that gets used for loading the + * service provider class. + * + * @throws IllegalArgumentException if spi, + * providerName or loader is + * null. + */ + ServiceProviderLoadingAction(Class spi, String providerName, + ClassLoader loader) + { + if (spi == null || providerName == null || loader == null) + throw new IllegalArgumentException(); + + this.spi = spi; + this.providerName = providerName; + this.loader = loader; + } + + + /** + * Loads an implementation class for a service provider, and creates + * a new instance of the loaded class by invoking its public + * no-argument constructor. + * + * @return a new instance of the class whose name was passed as + * providerName to the constructor. + * + * @throws ClassCastException if the service provider does not + * implement the spi interface that was passed to the + * constructor. + * + * @throws IllegalAccessException if the service provider class or + * its no-argument constructor are not public. + * + * @throws InstantiationException if the service provider class is + * abstract, an interface, a primitive type, an array + * class, or void; or if service provider class does not have a + * no-argument constructor; or if there some other problem with + * creating a new instance of the service provider. + */ + public Object run() + throws Exception + { + Class loadedClass; + Object serviceProvider; + + loadedClass = loader.loadClass(providerName); + serviceProvider = loadedClass.newInstance(); + + // Ensure that the loaded provider is actually implementing + // the service provider interface. + if (!spi.isInstance(serviceProvider)) + throw new ClassCastException(spi.getName()); + + return serviceProvider; + } +} -- cgit v1.1