[英]getting data from owl file in java
我得到了學生.i的所有成員使用以下代碼,但我得到的結果只有我的查詢是正確的。 當我在protege 4.3中運行該查詢時,他們給出了正確的結果但是java代碼中的問題。我不明白我做錯了什么。請在我的java類中提出錯誤。
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();
}
}
}
我的本體論是
<?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>
您沒有得到任何結果,因為您正在查詢空模型model1
而所有結果都包含在model
。 只需更改:
OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM);
... 至 ...
OntModel model1=ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM, model);
...然后您的后續查詢將可以訪問OntModel
內部的三元組。 證明可以在創建QueryExecution
實例的行中找到:
QueryExecution exe=QueryExecutionFactory.create(query, model1);
在此行中,您將創建一個引用新模型的查詢,該模型沒有您從文件中讀取的三元組。
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