刚刚开始学习jena推理，最近在学习有关SPARQL有关的知识，编了一个很小的程序但是遇到了一点问题，在aa.rdf-xml.owl中只定义了两个类，一个是company还有它的子类aa，现在已知aa,想查询到它是谁的子类，但总是查不出结果，很奇怪。以下是源程序：
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import com.hp.hpl.jena.query.Query;
import com.hp.hpl.jena.query.QueryExecution;
import com.hp.hpl.jena.query.QueryExecutionFactory;
import com.hp.hpl.jena.query.QueryFactory;
import com.hp.hpl.jena.query.ResultSet;
import com.hp.hpl.jena.query.ResultSetFormatter;
import com.hp.hpl.jena.rdf.model.InfModel;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.reasoner.Reasoner;
import com.hp.hpl.jena.reasoner.ReasonerRegistry;
public class Test6 {
public String filePath = "E://owlfile//aa.rdf-xml.owl";// 本体文件
Model model;//定义本体模型
//构造函数，加载本体模型
public Test6() {
model = ModelFactory.createDefaultModel();
loadModel();
}
/**
* 提交sparql的查询，输出返回结果
* @param queryStr
*/
public boolean runQuery(String queryStr) {
Query query = QueryFactory.create(queryStr);
Reasoner reasoner = ReasonerRegistry.getOWLReasoner();
InfModel inf = ModelFactory.createInfModel(reasoner, model);
QueryExecution qe = QueryExecutionFactory.create(query, model);
ResultSet results = qe.execSelect();
ResultSetFormatter.out(System.out,results,query);
results = null;
qe.close();
return true;
}
/**
* 加载本地文件形式的本体模型，失败系统退出
* @return
*/
private void loadModel() {
InputStreamReader in;
try {
FileInputStream file = new FileInputStream(filePath);
in = new InputStreamReader(file, "UTF-8");//处理中文
model.read(in, null);
in.close();
} catch (FileNotFoundException e) {
System.out.println("无法打开本体文件，程序将终止");
System.exit(0);
} catch (IOException e) {
e.printStackTrace();
System.exit(0);
}
}
public static void main(String[] args) {
String prefix = "PREFIX owl: <http://www.w3.org/2002/07/owl#>"+
"PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>"+
"PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> " +
"PREFIX base: <http://www.owl-ontologies.com/Ontology1331799803.owl#> ";
String k="base:aa";
String slect = "SELECT ?x ";
String where = "WHERE { "+
k+" rdfs:subClassOf ?x .}";
Test5 myLearn=new Test5();
String queryStr=prefix+slect+where;
myLearn.runQuery(queryStr);
}
}
其中aa.rdf-xml.owl文件的内容如下：
<?xml version="1.0"?>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:owl="http://www.w3.org/2002/07/owl#"
xmlns="http://www.owl-ontologies.com/Ontology1331799803.owl#"
xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xml:base="http://www.owl-ontologies.com/Ontology1331799803.owl" >
<rdf:Description rdf:about="">
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#Ontology"/>
</rdf:Description>
<rdf:Description rdf:about="#aa">
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#Class"/>
<rdfs:subClassOf rdf:resource="#company"/>
</rdf:Description>
<rdf:Description rdf:about="#company">
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#Class"/>
</rdf:Description>
</rdf:RDF>
<!-- Created with Protege (with OWL Plugin 3.2, Build 355) http://protege.stanford.edu -->
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2012/3/15 18:54:00
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使用SPARQL查询查不出结果，请教！
