[英]Get RDFNode from Jena ResultSet
如何從QueryExecution產生的ResultSet中檢索Jena RDFNode? 運行查詢后,我能夠看到正確的ResultSet,但結果僅提供節點的URI,任何人都可以告訴我需要執行哪些操作才能獲取RDF節點詳細信息。 這將使我提取每個屬性,以便以后使用。 我看到的解決方法是使用查詢來顯示實例的屬性,而不是實例本身。
當前結果:
http://assignment3.stdi.msmsuhail.ead/bpl.owl#Arsenal
預期結果:
<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查詢:
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代碼:
while(resultSet!=null && resultSet.hasNext()){
QuerySolution querySolution = resultSet.nextSolution();
System.out.println(querySolution.get("clubs").toString());
}
QuerySolution#get(String)的Javadoc說返回值是 RDFNode,因此您已經獲取的值是RDFNode。 如果您正在運行本地查詢(即,如果您有運行查詢的模型),則可以使用它來獲取屬性值,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"
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