Add EcoreSerializerBase, a base class to implement serializers to load and...

Add EcoreSerializerBase, a base class to implement serializers to load and save resources whose root element is of type {@code R}.

org.fortiss.tooling.kernel/trunk/src/org/fortiss/tooling/kernel/utils/EcoreSerializerBase.java

+/*--------------------------------------------------------------------------+
+$Id$
+|                                                                          |
+| Copyright 2016 ForTISS GmbH                     |
+|                                                                          |
+| Licensed 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.fortiss.tooling.kernel.utils;
+
+import java.io.IOException;
+import java.net.URL;
+import java.nio.charset.Charset;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.eclipse.core.runtime.FileLocator;
+import org.eclipse.core.runtime.Path;
+import org.eclipse.emf.common.util.URI;
+import org.eclipse.emf.ecore.EClass;
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.EPackage;
+import org.eclipse.emf.ecore.resource.Resource;
+import org.eclipse.emf.ecore.resource.ResourceSet;
+import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
+import org.eclipse.emf.ecore.xmi.XMLResource;
+import org.eclipse.emf.ecore.xmi.impl.XMLResourceFactoryImpl;
+import org.osgi.framework.Bundle;
+
+/**
+ * Base class to implement serializers to load and save resources whose root element is of type
+ * {@code R}.
+ * 
+ * @author barner
+ * @author $Author$
+ * @version $Rev$
+ * @ConQAT.Rating YELLOW Hash: 55E1AD7060144688DF8479369724773A
+ */
+public abstract class EcoreSerializerBase<R extends EObject> {
+
+	/** Namespace URI used to serialize resource. */
+	private String eNsURI;
+
+	/** {@link EPackage} that contains {@link EClass}es contained in the resource. */
+	private EPackage ePackage;
+
+	/** Factory used to build instances of elements contained in the resource. */
+	private Resource.Factory resourceFactory;
+
+	/** Encoding of resource. */
+	private Charset charset;
+
+	/** Name of schema file. */
+	private String schemaFileName;
+
+	/**
+	 * Constructs a new {@link EcoreSerializerBase}.
+	 * 
+	 * @param eNsURI
+	 *            Initializer for {@link #eNsURI}.
+	 * @param ePackage
+	 *            Initializer for {@link #ePackage}.
+	 * @param resourceFactory
+	 *            Initializer for {@link #resourceFactory}.
+	 * @param charset
+	 *            Initializer for {@link #charset}.
+	 * @param schemaFileName
+	 *            Initializer for {@link #schemaFileName}. May be {@code null}.
+	 */
+	public EcoreSerializerBase(final String eNsURI, final EPackage ePackage,
+			final Resource.Factory resourceFactory, final Charset charset,
+			final String schemaFileName) {
+		this.eNsURI = eNsURI;
+		this.ePackage = ePackage;
+		this.resourceFactory = resourceFactory;
+		this.charset = charset;
+		this.schemaFileName = schemaFileName;
+	}
+
+	/**
+	 * Loads a resource from a file and returns its root element.
+	 * 
+	 * @param pathName
+	 *            Path to file to be loaded
+	 * @return Root element of resource.
+	 * 
+	 * @throws IOException
+	 */
+	public final R load(final String pathName) throws IOException {
+		return load(createLoadURI(pathName));
+	}
+
+	/**
+	 * Loads a resource from a file and returns its root element.
+	 * 
+	 * @param uri
+	 *            Path to file to be loaded
+	 * @return Root element of resource.
+	 * 
+	 * @throws IOException
+	 */
+	public final R load(final URI uri) throws IOException {
+		ResourceSet resourceSet = createResourceSet(resourceFactory);
+		Resource resource = resourceSet.getResource(uri, true);
+
+		return getRootElement(resource.getContents().get(0));
+	}
+
+	/**
+	 * Saves a EMF model to a file.
+	 * 
+	 * @param rootElement
+	 *            Root element of model to serialized to XML.
+	 * @param pathName
+	 *            File to which configuration is to be written to.
+	 * 
+	 * @throws IOException
+	 */
+	public final void save(final R rootElement, final String pathName) throws IOException {
+		save(rootElement, createSaveURI(pathName));
+	}
+
+	/**
+	 * Saves a EMF model to a file.
+	 * 
+	 * @param rootElement
+	 *            Root element of model to serialized to XML.
+	 * @param uri
+	 *            {@link URI} to which configuration is to be written to.
+	 * 
+	 * @throws IOException
+	 */
+	public final void save(final R rootElement, final URI uri) throws IOException {
+		ResourceSet resourceSet = createResourceSet(new XMLResourceFactoryImpl());
+		Resource resource = resourceSet.createResource(uri);
+
+		if(resource instanceof XMLResource) {
+			((XMLResource)resource).setEncoding(charset.name());
+		}
+
+		resource.getContents().add(rootElement);
+		resource.save(getOptions());
+	}
+
+	/**
+	 * Returns the effective options to be used for serialization, i.e. the options returned by
+	 * {@link #getSpecificOptions()} modified to apply some enforced options.
+	 */
+	private Map<Object, Object> getOptions() {
+		Map<Object, Object> options = getSpecificOptions();
+
+		// Enforce the use of extended meta-data annotations. This ensures to preserve the
+		// element/attribute capitalization, the serialization type of string only elements, etc. to
+		// be confirming to the original XSD.
+		options.put(XMLResource.OPTION_EXTENDED_META_DATA, Boolean.TRUE);
+
+		// If a schema file as been specifed, enforce creation of xsi:schemaLocation
+		if(schemaFileName != null) {
+			options.put(XMLResource.OPTION_SCHEMA_LOCATION, Boolean.TRUE);
+		}
+
+		return options;
+	}
+
+	/**
+	 * Returns the options used in {@link #save(EObject, URI)}. Sub-classes may this method in
+	 * order to configure the right set of options for the corresponding file format.
+	 */
+	protected Map<Object, Object> getSpecificOptions() {
+		Map<Object, Object> options = new HashMap<Object, Object>();
+
+		// Prefer lean files and omit default content
+		options.put(XMLResource.OPTION_KEEP_DEFAULT_CONTENT, Boolean.FALSE);
+
+		// Pre-requisite for mixed content (e.g., also for comments)
+		options.put(XMLResource.OPTION_USE_LEXICAL_HANDLER, Boolean.TRUE);
+
+		return options;
+	}
+
+	/**
+	 * Extracts the root element from the resources document root element. Must be implemented by
+	 * sub-classes since this is specific to the corresponding file format.
+	 */
+	protected abstract R getRootElement(EObject contents);
+
+	/** Converts the given {@code pathName} into a file {@link URI}. */
+	protected final URI createFileURI(final String pathName) {
+		return URI.createFileURI(pathName);
+	}
+
+	/**
+	 * Converts the given {@code bundlePathName} into a {@link URI} within the given {@link Bundle}.
+	 * 
+	 * @throws IOException
+	 */
+	protected final URI createBundleURI(final String bundlePathName, final Bundle bundle)
+			throws IOException {
+
+		URL url = FileLocator.toFileURL(FileLocator.find(bundle, new Path(bundlePathName), null));
+		String pathName = url.getFile();
+
+		return URI.createFileURI(pathName);
+	}
+
+	/**
+	 * From the given {@code pathName}, derives the URI that is actually being {@link #load(String)}
+	 * ed. Sub-classes may override this method, e.g. to load files from a different context (such
+	 * as a {@link Bundle}).
+	 * 
+	 * @throws IOException
+	 */
+	protected URI createLoadURI(final String pathName) throws IOException {
+		return createFileURI(pathName);
+	}
+
+	/**
+	 * From the given {@code pathName}, derives the URI to which the model is actually being
+	 * {@link #save(EObject, String)}ed. Sub-classes may override this method, e.g. to save files
+	 * from a different context (such as a {@link Bundle}).
+	 * 
+	 * @throws IOException
+	 */
+	protected URI createSaveURI(final String pathName) throws IOException {
+		return createFileURI(pathName);
+	}
+
+	/**
+	 * Creates a {@link ResourceSet} and configures it with the given
+	 * {@link org.eclipse.emf.ecore.resource.Resource.Factory}.
+	 * 
+	 * @throws IOException
+	 */
+	private final ResourceSet createResourceSet(final Resource.Factory resourceFactory)
+			throws IOException {
+		ResourceSet resourceSet = new ResourceSetImpl();
+		resourceSet.getPackageRegistry().put(eNsURI, ePackage);
+
+		resourceSet.getResourceFactoryRegistry().getExtensionToFactoryMap()
+				.put(Resource.Factory.Registry.DEFAULT_EXTENSION, resourceFactory);
+
+		// If specified, add schema file to xsi:schemaLocation (enforces OPTION_SCHEMA_LOCATION).
+		if(schemaFileName != null) {
+			Resource packageResource = resourceSet.createResource(URI.createURI(schemaFileName));
+			packageResource.getContents().add(ePackage);
+		}
+
+		return resourceSet;
+	}
+}