Ontology 使用 Jenna 返回空值的简单 Sparql 查询

Question

基本上我在 Protégé 上创建了我的 Ontology，并且我已经验证了我的查询有效并返回了真实值，但是一旦我真的在我的 jsp 文件中将它们可视化，我的查询返回空值我试图调查和跟踪我的错误一周但找不到错误。

这是读取 ontology 文件的代码。

public static List<String> executeQueryOneColumn(ServletContext context, String queryString) {
        List<String> values = new ArrayList<>();
        Model model = FileManager.get().loadModel(context.getRealPath("/") + "/resources/LolOnto1.owl");
        Query query = QueryFactory.create(queryString);
        QueryExecution qexec = QueryExecutionFactory.create(query, model);
        try {
            ResultSet results = qexec.execSelect();

            System.out.println(results);
            while (results.hasNext()) {
                QuerySolution solution = results.nextSolution();

                Resource x = solution.getResource("x");
                values.add(x.getLocalName());
            }
        } finally {
            qexec.close();
        }
        return values;

    }

这是我执行 SparQL 查询以检索已存储在我自己的文件中的信息的地方。


@WebServlet(name = "QueryChampions", urlPatterns = {"/QueryChampions"})
public class QueryChampions extends HttpServlet {
    Logger logger = LoggerFactory.getLogger(QueryChampions.class);
    
    
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String champion = request.getParameter("champion");
        String ori = request.getParameter("origin");

        String queryString = "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>"
                + "PREFIX owl: <http://www.w3.org/2002/07/owl#>"
                + "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>"
                + "PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>"
                + "PREFIX lol: <http://www.LeagueOfLegends.ema/LolOntology#>"
                + " "
                + "SELECT * "
                + "WHERE "
                + "{ "
                + "  ?Champion   lol:comesFrom  ?origins  "
                + "}";

        queryString = String.format(queryString, champion, ori);
        List<List<String>> rows  = com.lol.champions.OwlReaderUtil.executeQueryTwoColumn(getServletContext(), queryString);
        System.out.println(rows);
        request.setAttribute("results", rows);
        request.setAttribute("champion", champion);
        request.setAttribute("origin", ori);
        request.getRequestDispatcher("/StandardSearch").forward(request, response);
   
    }

}

我尝试将它们列在我的 Web 应用程序的 jsp 文件中。

        <tr><th>Champion</th><th>Origin</th></tr>
        <c:forEach items="${results}" var="row" >
            <tr>
        <c:forEach items="${row}" var="v" >
            <td>
                ${v}
            </td>
        </c:forEach>    
            </tr>
        </c:forEach>
    </table>

Answer 1

问题与我的 executeOneColumn 函数有关，因为我传递了 getResource("x") 并且在我的 SparQl 查询中我得到了 ?Champion 和 ?Origins，所以如果我想要获得 x 我需要将所需元素之一重命名为 x.

Ontology 使用 Jenna 返回空值的简单 Sparql 查询

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