Added Xacml3JaxbHelper for processing XACML 3.0 schema-defined XML

documents with JAXB and schema validation

xacml-model/src/main/java/org/ow2/authzforce/xacml/Xacml3JaxbHelper.java

+/**
+ * Copyright 2012-2017 Thales Services SAS.
+ *
+ * This file is part of AuthzForce CE.
+ *
+ * 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.ow2.authzforce.xacml;
+
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+import javax.xml.XMLConstants;
+import javax.xml.bind.JAXBContext;
+import javax.xml.bind.JAXBException;
+import javax.xml.bind.Marshaller;
+import javax.xml.bind.Unmarshaller;
+import javax.xml.transform.Source;
+import javax.xml.transform.stream.StreamSource;
+import javax.xml.validation.Schema;
+import javax.xml.validation.SchemaFactory;
+
+import oasis.names.tc.xacml._3_0.core.schema.wd_17.ObjectFactory;
+
+import org.xml.sax.SAXException;
+
+/**
+ * XACML (XML) document - as defined by XACML 3.0 core specification's XML schema - processing utilities based on JAXB API
+ * 
+ */
+public final class Xacml3JaxbHelper
+{
+	private final static String[] CLASSPATH_RELATIVE_XACML_3_0_SCHEMA_LOCATIONS = { "xml.xsd", "xacml-core-v3-schema-wd-17.xsd" };
+
+	/**
+	 * Name of Java package of XACML-3.0-schema-derived classes
+	 */
+	private static final String XACML_3_0_JAXB_PACKAGE_NAME = "oasis.names.tc.xacml._3_0.core.schema.wd_17";
+
+	/**
+	 * XACML 3.0 schema
+	 */
+	public static final Schema XACML_3_0_SCHEMA;
+	static
+	{
+		final SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+		final Source[] schemaSources = new Source[2];
+		final ClassLoader classLoader = Xacml3JaxbHelper.class.getClassLoader();
+		for (int i = 0; i < CLASSPATH_RELATIVE_XACML_3_0_SCHEMA_LOCATIONS.length; i++)
+		{
+			final URL schemaURL = classLoader.getResource(CLASSPATH_RELATIVE_XACML_3_0_SCHEMA_LOCATIONS[i]);
+			if (schemaURL == null)
+			{
+				throw new RuntimeException("Invalid XML schema location on classpath (not found): " + CLASSPATH_RELATIVE_XACML_3_0_SCHEMA_LOCATIONS[i]);
+			}
+
+			schemaSources[i] = new StreamSource(schemaURL.toExternalForm());
+		}
+
+		try
+		{
+			XACML_3_0_SCHEMA = factory.newSchema(schemaSources);
+		}
+		catch (final SAXException e)
+		{
+			throw new RuntimeException("Failed to load XML schemas on classpath: " + Arrays.toString(CLASSPATH_RELATIVE_XACML_3_0_SCHEMA_LOCATIONS), e);
+		}
+	}
+
+	/**
+	 * JAXB context for (un)marshalling from/to JAXB objects derived from XACML 3.0 schema
+	 */
+	public static final JAXBContext XACML_3_0_JAXB_CONTEXT;
+	static
+	{
+		try
+		{
+			XACML_3_0_JAXB_CONTEXT = JAXBContext.newInstance(XACML_3_0_JAXB_PACKAGE_NAME, Xacml3JaxbHelper.class.getClassLoader());
+		}
+		catch (final JAXBException e)
+		{
+			throw new RuntimeException("Error instantiating JAXB context for (un)marshalling from/to XACML 3.0 objects", e);
+		}
+	}
+
+	/**
+	 * XACML 3.0 JAXB ObjectFactory
+	 */
+	public static final ObjectFactory XACML_3_0_OBJECT_FACTORY = new ObjectFactory();
+
+	/**
+	 * Creates XACML 3.0/JAXB unmarshaller with XACML 3.0 schema validation
+	 * 
+	 * @return unmarshaller
+	 * @throws JAXBException
+	 *             if an error was encountered while creating the Unmarshaller object
+	 */
+	public static Unmarshaller createXacml3Unmarshaller() throws JAXBException
+	{
+		final Unmarshaller unmarshaller = XACML_3_0_JAXB_CONTEXT.createUnmarshaller();
+		unmarshaller.setSchema(XACML_3_0_SCHEMA);
+		return unmarshaller;
+	}
+
+	/**
+	 * Creates XACML 3.0/JAXB marshaller with XACML 3.0 schema validation
+	 * 
+	 * @return marshaller
+	 * @throws JAXBException
+	 *             if an error was encountered while creating the Marshaller object
+	 */
+	public static Marshaller createXacml3Marshaller() throws JAXBException
+	{
+		final Marshaller marshaller = XACML_3_0_JAXB_CONTEXT.createMarshaller();
+		marshaller.setProperty(Marshaller.JAXB_ENCODING, StandardCharsets.UTF_8.name());
+		marshaller.setSchema(XACML_3_0_SCHEMA);
+		return marshaller;
+	}
+}