Question

我正在获得Student .i的所有成员.i使用以下代码，但我得到的结果只是我的查询是正确的。当我在protege 4.3中运行该查询时，他们给出了正确的结果但是java代码中的问题。我不明白我做错了什么。请在我的java类中提出错误。

class sparql1
    {  public static void main(String[] args) {

            String filename="modified2.owl";
            Model model=ModelFactory.createDefaultModel();
            OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM);

            try
            {
                File file=new File(filename);
                FileInputStream reader=new FileInputStream(file);
                model.read(reader,null);

                String query1=" PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX my: <http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#> SELECT  ?ind WHERE { ?ind rdf:type my:Student .}";

                com.hp.hpl.jena.query.Query query=QueryFactory.create(query1);
                QueryExecution exe=QueryExecutionFactory.create(query, model1);
                ResultSet RES=exe.execSelect();
                ResultSetFormatter.out(System.out, RES, query);
            }catch(Exception e)
            {
                e.printStackTrace();
            }
        }
    }

我的本体是

<?xml version="1.0"?>


<!DOCTYPE rdf:RDF [
    <!ENTITY owl "http://www.w3.org/2002/07/owl#" >
    <!ENTITY xsd "http://www.w3.org/2001/XMLSchema#" >
    <!ENTITY rdfs "http://www.w3.org/2000/01/rdf-schema#" >
    <!ENTITY rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#" >
    <!ENTITY untitled-ontology-10 "http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#" >
]>


<rdf:RDF xmlns="http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#"
     xml:base="http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10"
     xmlns:untitled-ontology-10="http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#"
     xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
     xmlns:owl="http://www.w3.org/2002/07/owl#"
     xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
    <owl:Ontology rdf:about="http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10"/>
     <!-- http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#hasAddress -->

    <owl:DatatypeProperty rdf:about="&untitled-ontology-10;hasAddress"/>



    <!-- http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#hasEmail -->

    <owl:DatatypeProperty rdf:about="&untitled-ontology-10;hasEmail"/>
   <owl:Class rdf:about="&untitled-ontology-10;Student"/>
    <!-- http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#Student2 -->

  <owl:NamedIndividual rdf:about="&untitled-ontology-10;Student2">
        <rdf:type rdf:resource="&untitled-ontology-10;Student"/>
        <hasEmail rdf:datatype="&xsd;string">asd</hasEmail>
        <hasAddress rdf:datatype="&xsd;string">sdsad</hasAddress>
    </owl:NamedIndividual>



    <!-- http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#student1 -->

    <owl:NamedIndividual rdf:about="&untitled-ontology-10;student1">
        <rdf:type rdf:resource="&untitled-ontology-10;Student"/>
        <hasEmail rdf:datatype="&xsd;string">fhgchg</hasEmail>
        <hasAddress rdf:datatype="&xsd;string">me</hasAddress>
    </owl:NamedIndividual>
    <!-- http://www.semanticweb.org/rohit/ontologies/2014/4/untitled-ontology-10#student3 -->

    <owl:NamedIndividual rdf:about="&untitled-ontology-10;student3">
        <rdf:type rdf:resource="&untitled-ontology-10;Student"/>
        <hasEmail rdf:datatype="&xsd;string">dsfdsf</hasEmail>
        <hasAddress rdf:datatype="&xsd;string">sdfds</hasAddress>
    </owl:NamedIndividual>
</rdf:RDF>

Answer 1

由于您在model1中包含所有结果时查询空model，因此无法获得结果。只需更改：

OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM);

...到......

OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM, model);

...然后您的后续查询将有权访问OntModel内的三元组。证明可在您创建QueryExecution实例的行中找到：

QueryExecution exe=QueryExecutionFactory.create(query, model1);

在此行中，您将创建一个引用新模型的查询，该模型没有您从文件中读取的三元组。

从java中的owl文件获取数据

1 个答案: