Rdf 他的查询是不正确的），但我在评论中看到，您稍后为其添加了前缀声明（提示：更新您的问题）
因此，您有属性Rdf 他的查询是不正确的），但我在评论中看到，您稍后为其添加了前缀声明（提示：更新您的问题）,rdf,sparql,jena,Rdf,Sparql,Jena,因此，您有属性http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#knows在数据库中，但您需要查询http://xmlns.com/foaf/0.1/knows。看到问题了吗？一切正常，您只是查询了错误的属性 更一般地说：简单地从web复制粘贴代码并不是学习如何使用这些工具的最佳方法。我建议你通过耶拿的一个教程，教你更多关于如何和为什么的知识。从长远来看，这将使您的生活更加轻松。您忘记了包含代码和查询。为
http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#knowshttp://xmlns.com/foaf/0.1/knows更一般地说：简单地从web复制粘贴代码并不是学习如何使用这些工具的最佳方法。我建议你通过耶拿的一个教程，教你更多关于如何和为什么的知识。从长远来看，这将使您的生活更加轻松。您忘记了包含代码和查询。为什么还有第二个
前缀前缀前缀前缀<?xml version="1.0"?>
<rdf:RDF xmlns="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#"
xml:base="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73"
xmlns:swp2="http://semwebprogramming.org/2009/ont/chp2#"
xmlns:untitled-ontology-73="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#"
xmlns:protege="http://protege.stanford.edu/plugins/owl/protege#"
xmlns:foaf="http://xmlns.com/foaf/0.1/"
xmlns:xsp="http://www.owl-ontologies.com/2005/08/07/xsp.owl#"
xmlns:ns66675="http://www.w3.org/2004/02/skos/core#"
xmlns:cmp="http://ld.thomsonreuters.com/ContentMarketplace/2013-10-15/#"
xmlns:ns36343="http://bioportal.bioontology.org/ontologies/umls/"
xmlns:Ontology1395931632451="http://www.semanticweb.org/ontologies/2014/2/Ontology1395931632451.owl#"
xmlns:ns20477="http://www.w3.org/2000/01/rdf-schema#"
xmlns:xml="http://www.w3.org/XML/1998/namespace"
xmlns:ns28717="http://purl.bioontology.org/ontology/HL7/"
xmlns:ns91299="http://www.w3.org/2002/07/owl#"
xmlns:schema="http://schema.org/"
xmlns:swrl="http://www.w3.org/2003/11/swrl#"
xmlns:owl2xml="http://www.w3.org/2006/12/owl2-xml#"
xmlns:dct="http://purl.org/dc/terms/"
xmlns:admin="http://webn.net/mvcb/"
xmlns:mds="http://ld.thomsonreuters.com/MetadataSystems/2013-10-15/#"
xmlns:swrlb="http://www.w3.org/2003/11/swrlb#"
xmlns:base="http://ld.thomsonreuters.com/MetadataSystems/2013-10-15/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<ns91299:Ontology rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73"/>
<!--
///////////////////////////////////////////////////////////////////////////////////////
//
// Object Properties
//
///////////////////////////////////////////////////////////////////////////////////////
-->
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#knowns -->
<ns91299:ObjectProperty rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#knowns">
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#ReflexiveProperty"/>
<ns20477:range rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
<ns20477:domain rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
</ns91299:ObjectProperty>
<!--
///////////////////////////////////////////////////////////////////////////////////////
//
// Data properties
//
///////////////////////////////////////////////////////////////////////////////////////
-->
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#name -->
<ns91299:DatatypeProperty rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#name">
<ns20477:domain rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
<ns20477:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
</ns91299:DatatypeProperty>
<!--
///////////////////////////////////////////////////////////////////////////////////////
//
// Classes
//
///////////////////////////////////////////////////////////////////////////////////////
-->
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person -->
<ns91299:Class rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person">
<ns20477:subClassOf>
<ns91299:Restriction>
<ns91299:onProperty rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#knowns"/>
<ns91299:someValuesFrom rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
</ns91299:Restriction>
</ns20477:subClassOf>
</ns91299:Class>
<!--
///////////////////////////////////////////////////////////////////////////////////////
//
// Individuals
//
///////////////////////////////////////////////////////////////////////////////////////
-->
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#amina -->
<ns91299:NamedIndividual rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#amina">
<rdf:type rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
<name>amina</name>
<knowns rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#george"/>
<knowns rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#john"/>
</ns91299:NamedIndividual>
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#george -->
<ns91299:NamedIndividual rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#george">
<rdf:type rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
<name>george</name>
<knowns rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#amina"/>
<knowns rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#nacira"/>
</ns91299:NamedIndividual>
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#john -->
<ns91299:NamedIndividual rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#john">
<rdf:type rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
<name>john</name>
</ns91299:NamedIndividual>
<!-- http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#nacira -->
<ns91299:NamedIndividual rdf:about="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#nacira">
<rdf:type rdf:resource="http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#person"/>
<name>nacira</name>
</ns91299:NamedIndividual>
</rdf:RDF>
<!-- Generated by the OWL API (version 3.4.5-SNAPSHOT) http://owlapi.sourceforge.net -->
package firstProject;
import java.util.Iterator;
//import com.hp.hpl.jena.ontology.OntModel;
//import com.hp.hpl.jena.ontology.OntModelSpec;
import com.hp.hpl.jena.query.Query;
import com.hp.hpl.jena.query.QueryFactory;
import com.hp.hpl.jena.query.QueryExecution;
import com.hp.hpl.jena.query.QueryExecutionFactory;
import com.hp.hpl.jena.query.QuerySolution;
import com.hp.hpl.jena.query.ResultSet;
import com.hp.hpl.jena.rdf.model.Literal;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.util.FileManager;
public class main {
public static void main(String[] args) {
// TODO Auto-generated method stub
sparqltest();}
static void sparqltest()
{
FileManager.get().addLocatorClassLoader(main.class.getClassLoader());
Model model= FileManager.get().loadModel("C:/Users/acer/workspace/firstProject/src/firstProject/onto1.rdf");
String queryString=
"PREFIX rdf:<http://www.semanticweb.org/acer/ontologies/2014/2/untitled-ontology-73#>"+
"SELECT * WHERE {"+
"?person foaf:name ?x. "+
"?person foaf:knows ?person2."+
"?person2 foaf:name ?y."+
"FILTER( ?y = \"john\")"+
"}";
Query query= QueryFactory.create(queryString);
QueryExecution qexec=QueryExecutionFactory.create(query, model);
try {
ResultSet results = qexec.execSelect();while ( results.hasNext()){
QuerySolution soln = results.nextSolution();
Literal name = soln.getLiteral("x");
System.out.println(name);
}
} finally {
qexec.close();
}}}