examples/org.eclipse.ocl.examples.build/src/org/eclipse/ocl/examples/build/utilities/ClasspathURIHandler.java

/*******************************************************************************
 * Copyright (c) 2014, 2018 Willink Transformations and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v20.html
 * 
 * Contributors:
 *     E.D.Willink - initial API and implementation
 *******************************************************************************/
package org.eclipse.ocl.examples.build.utilities;

import java.io.IOException;
import java.io.InputStream;
import java.net.URISyntaxException;
import java.util.Map;

import org.apache.log4j.Logger;
import org.eclipse.emf.common.util.EList;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.URIHandler;
import org.eclipse.emf.ecore.resource.impl.URIHandlerImpl;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.xtext.resource.ClassloaderClasspathUriResolver;

/**
 * ClasspathURIHandler may be installed by code such as 
 * <p>
 * 	resourceSet.getURIConverter().getURIHandlers().add(0, new ClasspathURIHandler());
 * <p>
 * to rectify the missing support for the classpath: protocol in Xtext (Bug 446073).
 */
public class ClasspathURIHandler extends URIHandlerImpl
{
	private Logger log = Logger.getLogger(getClass());	
	
	private final @NonNull ClassloaderClasspathUriResolver resolver = new ClassloaderClasspathUriResolver();

	@Override
	public boolean canHandle(URI uri) {
		return "classpath".equals(uri.scheme());
	}

	@Override
	public InputStream createInputStream(URI uri, Map<?, ?> options) throws IOException {
		try {
			URI resolvedURI = resolver.findResourceOnClasspath(getClass().getClassLoader(), uri);
			return super.createInputStream(resolvedURI, options);
		} catch (URISyntaxException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	/**
	 * Install support in an MWE2 script.
	 * @param resourceSet
	 */
	public void setResourceSet(ResourceSet resourceSet) {
		log.info("Setup classpath URI protocol");
		EList<URIHandler> uriHandlers = resourceSet.getURIConverter().getURIHandlers();
		if (!uriHandlers.contains(this)) {
			uriHandlers.add(0, this);
		}
	}
}