Jena Sparql和构造

Question

CONSTRUCT is an alternative SPARQL result clause to SELECT . Instead of returning a table of result values, CONSTRUCT returns an RDF graph. For instance, running this query in the following Java code produces an HttpException: 406 Unacceptable . But if instead of the CONSTRUCT block, I choose SELECT ?x , it's just fine. Does Jena support CONSTRUCT , and if so, how? Both queries are acceptable to the DBpedia endpoint .

PREFIX : <http://dbpedia.org/resource/>
PREFIX onto: <http://dbpedia.org/ontology/>

CONSTRUCT { 
    :France onto:anthem ?x
}

WHERE
{
  :France onto:anthem ?x .
}

Query query = QueryFactory.create("the query goes here");
QueryExecution qexec = QueryExecutionFactory.sparqlService("http://dbpedia.org/sparql",     query);
ResultSet results = qexec.execSelect();  
ResultSetFormatter.out(System.out, results, query);

Answer 1

Jena supports CONSTRUCT , but to get the result you need to call a different method, because execSelect and ResultSet are only for SELECT queries. Use this instead:

Model results = qexec.execConstruct();
results.write(System.out, "TURTLE");

Model is Jena's interface for accessing RDF graphs, see the javadocs for details.

Answer 2

ResultSetFormatter.out（System.out，results，query）找不到符号和标识符此时发生预期错误