Question

我想避免使用子字符串来消除我的示例本体：抽象或本体：标签，它与sparql资源管理器一起使用但是当我在jena中使用http查询时它不会给出任何结果...我在jena库（androjena）的android项目中尝试了这个查询

   SELECT ?type (STR(?l) AS ?label) {
   ?type a owl:Class;
         rdfs:label  ?l .
   FILTER (LANG(?l) = "en")
}

一旦我把它放在我的Jena httpquery (STR(?l) AS ?label)中，它就不再给出任何结果了。有人可以帮助我吗？

这是我试图改变以避免使用子串的代码部分：

 private String entityQuery(String entity, String keyWord, String language) {

        return addPrefix("rdfs: <http://www.w3.org/2000/01/rdf-schema#>") +
                addPrefix("ontology: <http://dbpedia.org/ontology/>") +

                addQuery("SELECT ?name  ?desc ?thumb  WHERE {\n"
                        +"?author a ontology:" + entity + ";\n"
                        +"rdfs:label ?name;\n"
                        +"ontology:abstract ?desc.\n"
                        +"FILTER(<bif:contains>(?desc,\"'"+keyWord+"'\") && langMatches(lang(?desc), \""+language+"\") " +
                        "&& langMatches( lang(?name), \""+language+"\"))\n"
                        +"OPTIONAL { ?author ontology:thumbnail ?thumb }.\n"
                        +"}ORDER BY ?name\n");
    }

    private LinkedList<Entity> collectEntities(ResultSet results) {
        LinkedList<Entity> temp = new LinkedList<>();
    /* do stuff with the results */
        while (results.hasNext()) {
            Entity a = new Entity();
            QuerySolution row = results.next();
            if (row.getResource("thumb") != null)
            a.setPictureURL(row.get("thumb").toString());
            a.setTitle(row.get("name").toString().substring(0, row.get("name").toString().indexOf("@")));
            a.setSummary(row.get("desc").toString().substring(0, row.get("desc").toString().indexOf("@")));
            temp.add(a);
        }
        return temp;
    }




    private String addPrefix(String prefix) {
        return "PREFIX " + prefix + "\n";
    }

    private String addQuery(String query) {
        return query;
    }

我在这里使用substring：

  a.setTitle(row.get("name").toString().substring(0, row.get("name").toString().indexOf("@")));
        a.setSummary(row.get("desc").toString().substring(0, row.get("desc").toString().indexOf("@")));

Jena dbpedia如何使用（STR（？foo）AS？foo2）？

0 个答案: