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-rw-r--r-- | sca-java-2.x/branches/2.0-Beta1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ContextClassLoaderServiceDiscoverer.java | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/sca-java-2.x/branches/2.0-Beta1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ContextClassLoaderServiceDiscoverer.java b/sca-java-2.x/branches/2.0-Beta1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ContextClassLoaderServiceDiscoverer.java new file mode 100644 index 0000000000..d40c37e4be --- /dev/null +++ b/sca-java-2.x/branches/2.0-Beta1/modules/extensibility/src/main/java/org/apache/tuscany/sca/extensibility/ContextClassLoaderServiceDiscoverer.java @@ -0,0 +1,194 @@ +/* + * 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. + */ + +package org.apache.tuscany.sca.extensibility; + +import java.io.IOException; +import java.lang.ref.WeakReference; +import java.net.URL; +import java.security.AccessController; +import java.security.PrivilegedAction; +import java.security.PrivilegedActionException; +import java.security.PrivilegedExceptionAction; +import java.util.Collection; +import java.util.Collections; +import java.util.Enumeration; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.logging.Level; +import java.util.logging.Logger; + +/** + * A ServiceDiscoverer that find META-INF/services/... using the Context ClassLoader. + * + * @version $Rev$ $Date$ + */ +public class ContextClassLoaderServiceDiscoverer implements ServiceDiscoverer { + private static final Logger logger = Logger.getLogger(ContextClassLoaderServiceDiscoverer.class.getName()); + + public class ServiceDeclarationImpl implements ServiceDeclaration { + private URL url; + private String className; + private Class<?> javaClass; + private Map<String, String> attributes; + + public ServiceDeclarationImpl(URL url, String className, Map<String, String> attributes) { + super(); + this.url = url; + this.className = className; + this.attributes = attributes; + } + + public Map<String, String> getAttributes() { + return attributes; + } + + public String getClassName() { + return className; + } + + public URL getLocation() { + return url; + } + + public Class<?> loadClass() throws ClassNotFoundException { + if (className == null) { + return null; + } + if (javaClass == null) { + javaClass = loadClass(className); + } + return javaClass; + } + + public Class<?> loadClass(String className) throws ClassNotFoundException { + return Class.forName(className, false, classLoaderReference.get()); + } + + @Override + public String toString() { + StringBuffer sb = new StringBuffer(); + sb.append("Location: ").append(url); + sb.append(" ClassLoader: ").append(classLoaderReference.get()); + sb.append(" Attributes: ").append(attributes); + return sb.toString(); + } + + public URL getResource(final String name) { + return AccessController.doPrivileged(new PrivilegedAction<URL>() { + public URL run() { + return classLoaderReference.get().getResource(name); + } + }); + } + + public boolean isAssignableTo(Class<?> serviceType) { + try { + loadClass(); + } catch (ClassNotFoundException e) { + // Ignore + } + return (javaClass != null && serviceType.isAssignableFrom(javaClass)); + } + + @Override + public Enumeration<URL> getResources(String name) throws IOException { + return Collections.enumeration(ContextClassLoaderServiceDiscoverer.this.getResources(name)); + } + } + + private WeakReference<ClassLoader> classLoaderReference; + + public ContextClassLoaderServiceDiscoverer() { + ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); + this.classLoaderReference = new WeakReference<ClassLoader>(classLoader); + } + + public ContextClassLoaderServiceDiscoverer(ClassLoader classLoader) { + if (classLoader == null) { + classLoader = Thread.currentThread().getContextClassLoader(); + } + this.classLoaderReference = new WeakReference<ClassLoader>(classLoader); + } + + public ClassLoader getContextClassLoader() { + //return classLoaderReference.get(); + return Thread.currentThread().getContextClassLoader(); + } + + private Collection<URL> getResources(final String name) throws IOException { + try { + return AccessController.doPrivileged(new PrivilegedExceptionAction<Collection<URL>>() { + public Collection<URL> run() throws IOException { + List<URL> urls = Collections.list(classLoaderReference.get().getResources(name)); + // Eliminate the duplicate URLs (which can be found from child/parent classloaders) + return new HashSet<URL>(urls); + } + }); + } catch (PrivilegedActionException e) { + throw (IOException)e.getException(); + } + } + + public ServiceDeclaration getServiceDeclaration(String name) throws IOException { + Collection<ServiceDeclaration> declarations = getServiceDeclarations(name); + if (declarations.isEmpty()) { + return null; + } else { + return declarations.iterator().next(); + } + } + + public Collection<ServiceDeclaration> getServiceDeclarations(String serviceName) { + Collection<ServiceDeclaration> descriptors = new HashSet<ServiceDeclaration>(); + + // http://java.sun.com/j2se/1.5.0/docs/api/javax/xml/xpath/XPathFactory.html + boolean isPropertyFile = "javax.xml.xpath.XPathFactory".equals(serviceName); + + String name = serviceName; + if (serviceName.startsWith("/")) { + // If the service name starts with /, treat it as the entry name + name = serviceName.substring(1); + } else { + // Use JDK SPI pattern + name = "META-INF/services/" + serviceName; + } + + boolean debug = logger.isLoggable(Level.FINE); + try { + for (final URL url : getResources(name)) { + if (debug) { + logger.fine("Reading service provider file: " + url.toExternalForm()); + } + + for (Map<String, String> attributes : ServiceDeclarationParser.load(url, isPropertyFile)) { + String className = attributes.get("class"); + ServiceDeclarationImpl descriptor = new ServiceDeclarationImpl(url, className, attributes); + descriptors.add(descriptor); + } + } + } catch (IOException e) { + logger.log(Level.SEVERE, e.getMessage(), e); + } + return descriptors; + + } + +} |