Question

使用pizza ontology，我希望能够查找American披萨的所有配料。如果我在Protégé打开本体，我可以看到American披萨有以下限制：

hasTopping some MozerellaTopping
hasTopping some TomatoTopping

如何通过Jena以编程方式获取相同的信息？

Answer 1

这是我的解决方案。我刚刚打印出你要求的字符串，但希望你能从中看到如何使用Jena OntAPI遍历本体图并挑选出你感兴趣的内容。

package examples;
import java.util.Iterator;
import com.hp.hpl.jena.ontology.*;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Resource;

public class PizzaExample
{
    /***********************************/
    /* Constants                       */
    /***********************************/
    public static String BASE = "http://www.co-ode.org/ontologies/pizza/pizza.owl";
    public static String NS = BASE + "#";

    /***********************************/
    /* External signature methods      */
    /***********************************/

    public static void main( String[] args ) {
        new PizzaExample().run();
    }

    public void run() {
        OntModel m = getPizzaOntology();
        OntClass american = m.getOntClass( NS + "American" );

        for (Iterator<OntClass> supers = american.listSuperClasses(); supers.hasNext(); ) {
            displayType( supers.next() );
        }
    }

    /***********************************/
    /* Internal implementation methods */
    /***********************************/

    protected OntModel getPizzaOntology() {
        OntModel m = ModelFactory.createOntologyModel( OntModelSpec.OWL_MEM );
        m.read( BASE );
        return m;
    }

    protected void displayType( OntClass sup ) {
        if (sup.isRestriction()) {
            displayRestriction( sup.asRestriction() );
        }
    }

    protected void displayRestriction( Restriction sup ) {
        if (sup.isAllValuesFromRestriction()) {
            displayRestriction( "all", sup.getOnProperty(), sup.asAllValuesFromRestriction().getAllValuesFrom() );
        }
        else if (sup.isSomeValuesFromRestriction()) {
            displayRestriction( "some", sup.getOnProperty(), sup.asSomeValuesFromRestriction().getSomeValuesFrom() );
        }
    }

    protected void displayRestriction( String qualifier, OntProperty onP, Resource constraint ) {
        String out = String.format( "%s %s %s",
                                    qualifier, renderURI( onP ), renderConstraint( constraint ) );
        System.out.println( "american pizza: " + out );
    }

    protected Object renderConstraint( Resource constraint ) {
        if (constraint.canAs( UnionClass.class )) {
            UnionClass uc = constraint.as( UnionClass.class );
            // this would be so much easier in ruby ...
            String r = "union{ ";
            for (Iterator<? extends OntClass> i = uc.listOperands(); i.hasNext(); ) {
                r = r + " " + renderURI( i.next() );
            }
            return r + "}";
        }
        else {
            return renderURI( constraint );
        }
    }

    protected Object renderURI( Resource onP ) {
        String qName = onP.getModel().qnameFor( onP.getURI() );
        return qName == null ? onP.getLocalName() : qName;
    }
}

产生以下输出：

american pizza: some pizza:hasTopping pizza:MozzarellaTopping
american pizza: some pizza:hasTopping pizza:PeperoniSausageTopping
american pizza: some pizza:hasTopping pizza:TomatoTopping
american pizza: all pizza:hasTopping union{  pizza:MozzarellaTopping pizza:TomatoTopping pizza:PeperoniSausageTopping}

Answer 2

现在（使用Apache Jena 3.x.x）（对于Jena2而言）仍然存在org.apache.jena.ontology.OntModel和pizza.owl的一个可能问题，即Jena OntAPI仅支持OWL1，而pizza是OWL2本体。

虽然上面的示例无关紧要（'存在量化'限制对于OWL1和OWL2看起来都相同，并且Jena API可以处理它），但在一般情况下，您不能使用OntModel处理本体同样容易。作为一种选择，有一种方法可以从ONT-API调用ru.avicomp.ontapi.jena.model.OntGraphModel。它基于与耶拿OntModel相同的原则，但它强烈适用于OWL2，而且不是InfModel（在撰写本文时）。也许对某人有帮助。

使用示例（仅从类的限制中获取对象 - 某些值）：

    String web = "https://raw.githubusercontent.com/avicomp/ont-api/master/src/test/resources/ontapi/pizza.ttl";
    // create an OWL2 RDF-view (Jena Model):
    OntGraphModel m = ru.avicomp.ontapi.jena.OntModelFactory.createModel();
    // load pizza ontology from web
    m.read(web, "ttl");
    // find class and property
    OntClass clazz = m.getOntClass(m.expandPrefix(":American"));
    OntNOP prop = m.getObjectProperty(m.expandPrefix(":hasTopping"));
    // list and print all some values from restrictions with desired property
    clazz.superClasses()
            .filter(c -> c.canAs(OntCE.ObjectSomeValuesFrom.class))
            .map(c -> c.as(OntCE.ObjectSomeValuesFrom.class))
            .filter(c -> prop.equals(c.getProperty()))
            .map(x -> x.getValue())
            .forEach(System.out::println);

输出：

http://www.co-ode.org/ontologies/pizza/pizza.owl#PeperoniSausageTopping(OntClass)
http://www.co-ode.org/ontologies/pizza/pizza.owl#TomatoTopping(OntClass)
http://www.co-ode.org/ontologies/pizza/pizza.owl#MozzarellaTopping(OntClass)

使用Jena获取对类的OWL限制

2 个答案: