Model model = ModelFactory.createDefaultModel();
 Resource resource1 =  model.createResource(ns + "TCP");
 Resource resource2 =  model.createResource(ns + "Transport");
 Resource resource3 =  model.createResource(ns + "Service");

 Property property1  =  model.createProperty(ns, "isChildOf");
 Property property2  =   model.createProperty(rdfs, "subClassOf");

 Statement st1 = model.createStatement(resource1, property1, resource2);  
Statement st2 = model.createStatement(resource2, property2, resource3);

 model.add(st1);
 model.add(st2);

然后我写了一个sparql的query语句如下：
 String queryString =  "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> "
                       + "PREFIX ns:  <http://www.comp.nus.edu.sg/dpf/> "
                       + "SELECT ?out "
                       + "WHERE { "
                       + "?var rdfs:subClassOf ?out."
                       + "\"TCP\" ns:isChildOf ?var.}";
        Query query = QueryFactory.create(queryString);
        QueryExecution exc = QueryExecutionFactory.create(query, model);
        ResultSet result = exc.execSelect();
        ResultSetFormatter fsf = new ResultSetFormatter();
        ResultSetFormatter.out(System.out, result, query);

可是执行结果为空，百思不得其解，请高手赐教