DBpedia Jena Query返回null [英] DBpedia Jena Query returning null
本文介绍了DBpedia Jena Query返回null的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我只是想在DBpedia上运行一个小查询,查询本身有效,看到它这里,但我不知道为什么它在与Jena这样做时会回来,我会变空。
I'm just trying to run a small query on DBpedia, the query itself works, see it here, but I don't why its returning when doing so with Jena, I'm getting null.
String service = "http://dbpedia.org/sparql";
String queryString = "";
queryString = "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT ?label" +
"WHERE {" +
"<http://dbpedia.org/resource/Quatre_Bornes> <http://dbpedia.org/ontology/country> ?y ."+
"?y rdfs:label ?label ."+
"FILTER (LANG(?label) = 'en')"+
"}";
Query query = QueryFactory.create(queryString);
QueryEngineHTTP qexec = QueryExecutionFactory.createServiceRequest(service, query);
ResultSet results = qexec.execSelect();
for ( ; results.hasNext() ; ) {
QuerySolution soln = results.nextSolution() ;
System.out.println(soln.getLiteral("label"));
}
有任何建议吗?
推荐答案
这是如此令人尴尬,查询中存在空间问题:
that is so embarassing, there is space problem in the query:
String service = "http://dbpedia.org/sparql";
String queryString = "";
queryString = "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT ?label " +
"WHERE {" +
"<http://dbpedia.org/resource/Quatre_Bornes> <http://dbpedia.org/ontology/country> ?y ."+
"?y rdfs:label ?label ."+
"FILTER (LANG(?label) = 'en')"+
"}";
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