| /******************************************************************************* |
| * Copyright (c) 2003, 2016 IBM Corporation and others. |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| |
| package org.eclipse.osgi.internal.url; |
| |
| import java.io.IOException; |
| import java.net.ContentHandler; |
| import java.net.URLConnection; |
| import org.osgi.framework.*; |
| import org.osgi.service.url.URLConstants; |
| import org.osgi.util.tracker.ServiceTracker; |
| import org.osgi.util.tracker.ServiceTrackerCustomizer; |
| |
| /** |
| * The ContentHandlerProxy is a ContentHandler that acts as a proxy for registered ContentHandlers. |
| * When a ContentHandler is requested from the ContentHandlerFactory and it exists in the service |
| * registry, a ContentHandlerProxy is created which will pass all the requests from the requestor to |
| * the real ContentHandler. We can't return the real ContentHandler from the ContentHandlerFactory |
| * because the JVM caches ContentHandlers and therefore would not support a dynamic environment of |
| * ContentHandlers being registered and unregistered. |
| */ |
| public class ContentHandlerProxy extends ContentHandler implements ServiceTrackerCustomizer<ContentHandler, ServiceReference<ContentHandler>> { |
| protected ContentHandler realHandler; |
| |
| //TODO avoid type-based names |
| protected ServiceTracker<ContentHandler, ServiceReference<ContentHandler>> contentHandlerServiceTracker; |
| |
| protected BundleContext context; |
| protected ServiceReference<ContentHandler> contentHandlerServiceReference; |
| |
| protected String contentType; |
| |
| protected int ranking = Integer.MIN_VALUE; |
| |
| public ContentHandlerProxy(String contentType, ServiceReference<ContentHandler> reference, BundleContext context) { |
| this.context = context; |
| this.contentType = contentType; |
| |
| // In case the reference == null, the proxy is constructed with DefaultContentHandler for a Content Handler |
| // until a real ContentHandler for this mime-type is registered |
| setNewHandler(reference, getRank(reference)); |
| |
| contentHandlerServiceTracker = new ServiceTracker<>(context, ContentHandler.class.getName(), this); |
| URLStreamHandlerFactoryImpl.secureAction.open(contentHandlerServiceTracker); |
| } |
| |
| private void setNewHandler(ServiceReference<ContentHandler> reference, int rank) { |
| if (contentHandlerServiceReference != null) |
| context.ungetService(contentHandlerServiceReference); |
| |
| contentHandlerServiceReference = reference; |
| ranking = rank; |
| |
| if (reference == null) |
| realHandler = new DefaultContentHandler(); |
| else |
| realHandler = URLStreamHandlerFactoryImpl.secureAction.getService(reference, context); |
| } |
| |
| /** |
| * @see org.osgi.util.tracker.ServiceTrackerCustomizer#addingService(ServiceReference) |
| */ |
| @Override |
| public ServiceReference<ContentHandler> addingService(ServiceReference<ContentHandler> reference) { |
| //check to see if our contentType is being registered by another service |
| Object prop = reference.getProperty(URLConstants.URL_CONTENT_MIMETYPE); |
| if (prop instanceof String) { |
| prop = new String[] {(String) prop}; |
| } |
| if (!(prop instanceof String[])) { |
| return null; |
| } |
| String[] contentTypes = (String[]) prop; |
| for (int i = 0; i < contentTypes.length; i++) { |
| if (contentTypes[i].equals(contentType)) { |
| //If our contentType is registered by another service, check the service ranking and switch URLStreamHandlers if nessecary. |
| int newServiceRanking = getRank(reference); |
| if (newServiceRanking > ranking || contentHandlerServiceReference == null) |
| setNewHandler(reference, newServiceRanking); |
| return (reference); |
| } |
| } |
| |
| //we don't want to continue hearing events about a ContentHandler service not registered under our contentType |
| return (null); |
| } |
| |
| /** |
| * @see org.osgi.util.tracker.ServiceTrackerCustomizer#modifiedService(ServiceReference, Object) |
| */ |
| |
| @Override |
| public void modifiedService(ServiceReference<ContentHandler> reference, ServiceReference<ContentHandler> service) { |
| int newrank = getRank(reference); |
| if (reference == contentHandlerServiceReference) { |
| if (newrank < ranking) { |
| // The ContentHandler we are currently using has dropped it's ranking below a ContentHandler |
| // registered for the same protocol. We need to swap out ContentHandlers. |
| // this should get us the highest ranked service, if available |
| ServiceReference<ContentHandler> newReference = contentHandlerServiceTracker.getServiceReference(); |
| if (newReference != contentHandlerServiceReference && newReference != null) { |
| setNewHandler(newReference, ((Integer) newReference.getProperty(Constants.SERVICE_RANKING)).intValue()); |
| } |
| } |
| } else if (newrank > ranking) { |
| // the service changed is another URLHandler that we are not currently using |
| // If it's ranking is higher, we must swap it in. |
| setNewHandler(reference, newrank); |
| } |
| } |
| |
| /** |
| * @see org.osgi.util.tracker.ServiceTrackerCustomizer#removedService(ServiceReference, Object) |
| */ |
| @Override |
| public void removedService(ServiceReference<ContentHandler> reference, ServiceReference<ContentHandler> service) { |
| //check to see if our URLStreamHandler was unregistered. |
| if (reference != contentHandlerServiceReference) |
| return; |
| // If so, look for a lower ranking URLHandler |
| // this should get us the highest ranking service left, if available |
| ServiceReference<ContentHandler> newReference = contentHandlerServiceTracker.getServiceReference(); |
| // if newReference == null then we will use the DefaultContentHandler here |
| setNewHandler(newReference, getRank(newReference)); |
| } |
| |
| /** |
| * @see java.net.ContentHandler#getContent(URLConnection) |
| */ |
| |
| @Override |
| public Object getContent(URLConnection uConn) throws IOException { |
| return realHandler.getContent(uConn); |
| } |
| |
| private int getRank(ServiceReference<?> reference) { |
| if (reference == null) |
| return Integer.MIN_VALUE; |
| Object property = reference.getProperty(Constants.SERVICE_RANKING); |
| return (property instanceof Integer) ? ((Integer) property).intValue() : 0; |
| } |
| |
| class DefaultContentHandler extends ContentHandler { |
| |
| /** |
| * @see java.net.ContentHandler#getContent(URLConnection) |
| */ |
| @Override |
| public Object getContent(URLConnection uConn) throws IOException { |
| return uConn.getInputStream(); |
| } |
| } |
| } |