rdf - 从 Jena ResultSet 获取 RDFNode

Question

如何从 QueryExecution 生成的结果集中检索 Jena RDFNode？运行查询后我能够看到正确的结果集，但结果仅提供节点的 URI，谁能告诉我需要做什么才能获取 RDF 节点详细信息。这将让我提取每个属性，我以后可以操作这些属性。我看到的解决方法是使用显示实例属性而不是实例本身的查询。

当前结果:

http://assignment3.stdi.msmsuhail.ead/bpl.owl#Arsenal

预期结果:

<rdf:Description rdf:about="http://assignment3.stdi.msmsuhail.ead/bpl.owl#Arsenal">
    <bpl:hasStadiumLocation rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Holloway</bpl:hasStadiumLocation>
    <rdf:type rdf:resource="http://assignment3.stdi.msmsuhail.ead/bpl.owl#Clubs"/>
    <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#NamedIndividual"/>
    <bpl:hasStadiumName rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Emirates Stadium</bpl:hasStadiumName>
    <bpl:hasPlayer rdf:resource="http://assignment3.stdi.msmsuhail.ead/bpl.owl#TheoWalcott"/>
    <bpl:hasPlayer rdf:resource="http://assignment3.stdi.msmsuhail.ead/bpl.owl#MikelArteta"/>
    <bpl:hasName rdf:datatype="http://www.w3.org/2001/XMLSchema#string">Arsenal</bpl:hasName>
    <bpl:hasNumberSeats rdf:datatype="http://www.w3.org/2001/XMLSchema#integer">60355</bpl:hasNumberSeats>
    <bpl:hasManager rdf:resource="http://assignment3.stdi.msmsuhail.ead/bpl.owl#ArseneWenger"/>
    <bpl:hasPlayer rdf:resource="http://assignment3.stdi.msmsuhail.ead/bpl.owl#AaronRamsey"/>
</rdf:Description>

SPARQL 查询:

SELECT DISTINCT  ?clubs ?clubName 
WHERE {
    ?Club bpl:hasPlayer ?players.
    ?Club bpl:hasManager  ?managers.
    ?players bpl:hasClub ?clubs .
    ?players bpl:hasAge ?playerAge.
    ?players bpl:hasName ?playerName.
    ?players bpl:hasNationality ?playerNationality.
    ?players bpl:hasPlayingPosition ?playerPosition.
    ?players bpl:isRetired ?playerIsRetired.
    ?clubs bpl:hasName ?clubName.
    ?clubs bpl:hasNumberSeats ?clubSeats.
    ?clubs bpl:hasStadiumName ?clubStadiumName .
    ?clubs bpl:hasStadiumLocation ?clubStadiumLocation.
    ?managers bpl:hasAge ?managerAge.
    ?managers bpl:hasName ?managerName.
    ?managers bpl:hasNationality ?managerNationality.
    ?managers bpl:isManager ?isManager.
} 
ORDER BY ASC (?clubName)

Java 代码:

    while(resultSet!=null && resultSet.hasNext()){
                   QuerySolution querySolution = resultSet.nextSolution();
                   System.out.println(querySolution.get("clubs").toString());                              
    } 

Answer 1

QuerySolution#get(String) 的 Javadoc说返回值是一个 RDFNode，所以你得到的值已经是一个 RDFNode。如果您正在运行本地查询(即，如果您有查询运行所针对的模型)，那么您可以使用它获取属性值，例如，

RDFNode clubNode = querySolution.get( "club" );
Resource club = clubNode.asResource().inModel( model );
Statement stmt = club.getProperty( BPL.hasStadiumLocation );
System.out.println( stmt.getObject() ); // prints "Holloway"