Use Jena to query wikidata

问题

Currently, Wikidata has a SPARQL endpoint "https://query.wikidata.org/", I would like to query this site using Jena (3.0.1), I use the following code but I got an error message "Endpoint returned Content-Type: text/html which is not currently supported for SELECT queries". Is there a way to solve it? the same code works fine with dbpedia. Thanks

queryString = "PREFIX bd: <http://www.bigdata.com/rdf#>\n" +
                "PREFIX wikibase: <http://wikiba.se/ontology#>\n" +
                "PREFIX wdt: <http://www.wikidata.org/prop/direct/>\n" +
                "PREFIX wd: <http://www.wikidata.org/entity/>\n" +
                "SELECT DISTINCT ?country ?countryLabel\n" +
                "WHERE\n" +
                "{\n" +
                "\t?country wdt:P31 wd:Q3624078 .\n" +
                "    ?country wdt:P1622 wd:Q13196750.\n" +
                "    ?country wdt:P30 wd:Q15\n" +
                "\tFILTER NOT EXISTS {?country wdt:P31 wd:Q3024240}\n" +
                "\tSERVICE wikibase:label { bd:serviceParam wikibase:language \"en\" }\n" +
                "}\n" +
                "ORDER BY ?countryLabel";
        query = QueryFactory.create(queryString);
        qexec = QueryExecutionFactory.sparqlService("https://query.wikidata.org/", queryString);
        try {
            ResultSet results = qexec.execSelect();
            ResultSetFormatter.out(System.out, results, query);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        } finally {
            qexec.close();
        }

回答1:

According to the documentation, the endpoint has a /sparql at the end. It says

SPARQL queries can be submitted directly to the SPARQL endpoint with a GET request to https://query.wikidata.org/sparql?query={SPARQL} (POST and other method requests will be denied with a "403 Forbidden"). The result is returned as XML by default, or as JSON if either the query parameter format=json or the header Accept: application/sparql-results+json are provided.

来源：https://stackoverflow.com/questions/36535702/use-jena-to-query-wikidata

标签

java

sparql

semantic-web

wikidata