On 12/09/11 03:44, Herli Joaquim de Menezes wrote:
Hello, Friends
I don't know how to solve this. I wrote a simple Jena web application in
order to query on a simple LOM RDF file. I am using a MVC model, so that the
control view is composed by servlets. Excuse me for the long post...but here
is the code snippet:
{..............}
String filename = "/WEB-INF/TesteLOM2.rdf";
ServletContext context = getServletContext();
InputStream in = context.getResourceAsStream(filename);
if (in != null) {
Model model = ModelFactory.createMemModelMaker()
.createDefaultModel();
model.read(in, null);
// null base URI, since model URIs are absolute
in.close();
@SuppressWarnings("unchecked")
List<String> lista = (List<String>) request.getSession()
.getAttribute("sugestao");
String palavrachave = null;
for (Iterator<String> iter = lista.iterator(); iter.hasNext();)
{
palavrachave = iter.next();
// Creates a query....
String queryString =
"PREFIX NS1:<http://www.exemplo.com/#> "
+ "PREFIX rdf:<
http://www.w3.org/1999/02/22-rdf-syntax-ns#>"
+ "PREFIX dcterms:<http://purl.org/dc/terms/>"
+ "PREFIX dc:<http://purl.org/dc/elements/1.1/>"
+ "PREFIX lom:<
http://ltsc.ieee.org/rdf/lomv1p0/terms/> "
+ "PREFIX lomvoc:<
http://ltsc.ieee.org/rdf/lomv1p0/vocabulary#>"
+ "SELECT ?title ?LearningResourceType ?location "
+ "WHERE {"
+ " ?keyword lom:keyword \""
+ palavrachave
+ "\""
+ " ."
+ " ?keyword dc:title ?title ."
+ " ?keyword lom:location ?location ."
+ " ?keyword lomvoc:LearningResourceType
?LearningResourceType."
+ "}";
Query query = QueryFactory.create(queryString);
// get the results...
QueryExecution qe = QueryExecutionFactory.create(query,
model);
ResultSet results = qe.execSelect();
request.getSession().setAttribute("results", results);
// Just for debugging....
ResultSetFormatter.out(System.out, results, query);
A ResultSet is an iterator.
ResultSetFormatter.out(System.out, results, query); reads the iterator
so at the end, there are no more results. iterator.hasNext is false.
If you want to print it out and pass it to ther code, you need to create
a copy or rewindable ResultSet (see ResultSetFactory).
qe.close();
}
request.getAttribute("results");
??
VIEW is a JSP to render the results:
{...........}
<form method="post" action="ControlaBuscaDeObjetos">
<fieldset>
<legend> Objetos Selecionados</legend>
<p> some explanation...</p>
<table>
<c:forEach items="${results}" var="item">
This iterator has ended.
<tr>
<td>${item}</td>
</tr>
</c:forEach>
</table>
</fieldset>
</form>
++++++++++++++++++++++++
The terminal output is OK:
Andy
-------------------------------------------------------------------------
| title | LearningResourceType | location |
=========================================================================
| "Força Resultante" | "narrativetext" | "file:///path" |
| "Calculo da Força Resultante" | "Problem Statement" | "file:///path" |
-------------------------------------------------------------------------
------------------------------------------------------------
| title | LearningResourceType | location |
============================================================
| "Momento Linear" | "Problem Statement" | "file:///path" |
------------------------------------------------------------
-------------------------------------------------------------------------------
| title | LearningResourceType |
location |
===============================================================================
| "Velocidade" | "narrativetext" |
"file:///path" |
| "Velocidade no Movimento Harmônico" | "Problem Statement" |
"file:///path" |
| "Velocidade " | "Problem Statement" |
"file:///path" |
-------------------------------------------------------------------------------
------------------------------------------------------
| title | LearningResourceType | location |
======================================================
| "Derivada" | "narrativetext" | "file:///path" |
------------------------------------------------------
-------------------------------------------------------------
| title | LearningResourceType | location |
=============================================================
| "Função Contínua" | "narrativetext" | "file:///path" |
-------------------------------------------------------------
-------------------------------------------------------
| title | LearningResourceType | location |
=======================================================
| "Sequência" | "narrativetext" | "file:///path" |
-------------------------------------------------------
++++++++++++++++++++++++++++++++++++++
But I can't get it rendered at JSP. What am I doing wrong?
