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JenaUtils.java
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JenaUtils.java
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/**
* Copyright (C) 2020 Czech Technical University in Prague
* <p>
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any
* later version.
* <p>
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details. You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package cz.cvut.kbss.ontodriver.jena.util;
import cz.cvut.kbss.ontodriver.model.Assertion;
import cz.cvut.kbss.ontodriver.model.LangString;
import cz.cvut.kbss.ontodriver.model.NamedResource;
import cz.cvut.kbss.ontodriver.model.Value;
import org.apache.jena.datatypes.xsd.XSDDatatype;
import org.apache.jena.datatypes.xsd.impl.RDFLangString;
import org.apache.jena.rdf.model.Literal;
import org.apache.jena.rdf.model.RDFNode;
import org.apache.jena.rdf.model.ResourceFactory;
import java.net.URL;
/**
* Utility methods for working with Jena API.
*/
public class JenaUtils {
private JenaUtils() {
throw new AssertionError();
}
/**
* Resolves whether the specified value is a resource identifier.
* <p>
* Only absolute IRIs are supported (i.e. no blank node identifiers).
*
* @param value The value to check
* @return {@code true} if the value is either an URI or an URL
*/
public static boolean isResourceIdentifier(Object value) {
if (value instanceof NamedResource || value instanceof java.net.URI || value instanceof URL) {
return true;
}
if (!(value instanceof String)) {
return false;
}
try {
final java.net.URI uri = java.net.URI.create(value.toString());
return uri.isAbsolute();
} catch (IllegalArgumentException e) {
return false;
}
}
/**
* Transforms the specified value to an {@link RDFNode}, be it a resource or a literal.
*
* @param assertion Assertion representing the asserted property
* @param value Value to transform
* @return Jena RDFNode
*/
public static RDFNode valueToRdfNode(Assertion assertion, Value<?> value) {
if (JenaUtils.isResourceIdentifier(value.getValue())) {
return ResourceFactory.createResource(value.stringValue());
} else {
return assertion.hasLanguage() ?
ResourceFactory.createLangLiteral(value.stringValue(), assertion.getLanguage()) :
ResourceFactory.createTypedLiteral(value.getValue());
}
}
public static Object literalToValue(Literal literal) {
if (literal.getDatatype().equals(RDFLangString.rdfLangString)) {
return new LangString(literal.getString(), literal.getLanguage());
}
// This is because Jena returns XSD:long values as Integers, when they fit. But we don't want this.
return literal.getDatatype().equals(XSDDatatype.XSDlong) ? literal.getLong() : literal.getValue();
}
}