Example of a jena custom datatype.

ExampleCustomDatatype.java

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 * to you under the Apache License, Version 2.0 (the
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package examples;

import java.io.StringReader;
import java.util.UUID;
import java.util.function.Function;

import org.apache.jena.datatypes.BaseDatatype;
import org.apache.jena.datatypes.DatatypeFormatException;
import org.apache.jena.datatypes.RDFDatatype;
import org.apache.jena.datatypes.TypeMapper;
import org.apache.jena.graph.Graph;
import org.apache.jena.graph.Node;
import org.apache.jena.graph.NodeFactory;
import org.apache.jena.graph.impl.LiteralLabelFactory;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFDataMgr;
import org.apache.jena.sparql.graph.GraphFactory;
import org.apache.jena.sparql.sse.SSE;

public class ExampleCustomDatatype {

    public static void main(String ... a) {
        registerCustomDatatype(UUID.class, "java:java.util.UUID", UUID::fromString, UUID::toString);

        // Node from Java object
        UUID uuid = UUID.fromString("00000000-0000-0000-0000-00000000AAAA");
        Node n1 = NodeFactory.createLiteral(LiteralLabelFactory.createTypedLiteral(uuid));
        System.out.println(n1.getLiteralValue().getClass());

        // Get datatype.
        RDFDatatype dt = TypeMapper.getInstance().getTypeByName("java:java.util.UUID");
        Node n1a = NodeFactory.createLiteral("00000000-0000-0000-0000-00000000AAAA", dt);
        System.out.println(n1a.getLiteralValue().getClass());

        // Parse
        Node n2 = SSE.parseNode("'00000000-0000-0000-0000-00000000AAAA'^^<java:java.util.UUID>");
        System.out.println(n2.getLiteralValue().getClass());

        // Parse
        String rdfStr = "_:a <http://example.org/p1> '00000000-0000-0000-0000-00000000AAAA'^^<java:java.util.UUID> .";
        Graph graph = GraphFactory.createDefaultGraph();
        RDFDataMgr.read(graph, new StringReader(rdfStr), null, Lang.NT);

        // Get the parsed
        System.out.println(graph.find().next().getObject().getLiteralValue().getClass());
    }

    static <X> void registerCustomDatatype(Class<X> clazz, String datatypeURI,
                                           Function<String, X> parser,
                                           Function<X, String> toLexicalForm) {
        RDFDatatype customeDatatype = customDatatype(clazz, datatypeURI, parser, toLexicalForm);
        TypeMapper.getInstance().registerDatatype(customeDatatype);
    }

    /** Custom datatype for {@code X} */
    static <X> RDFDatatype customDatatype(Class<X> clazz, String uri, Function<String, X> parser, Function<X, String> toLexicalForm) {
        return new BaseDatatype(uri) {
            @Override
            public Class<X> getJavaClass() {
                return clazz;
            }

            @Override
            public String unparse(Object value) {
                @SuppressWarnings("unchecked")
                X x = (X)value;
                return toLexicalForm.apply(x);
            }

            @Override
            public X parse(String lexicalForm) throws DatatypeFormatException {
                try {
                    return parser.apply(lexicalForm);
                } catch (Throwable th) {
                    throw new DatatypeFormatException();
                }
            }
        };
    }
}