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| - %META:TOPICPARENT{name="VirtJenaProvider"}%
%VOSWARNING%
---+ Virtuoso Jena Provider - SPARQL Example 9
<verbatim>
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.RDFNode;
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.graph.Node;
import com.hp.hpl.jena.graph.Graph;
import com.hp.hpl.jena.rdf.model.*;
import java.util.Iterator;
import virtuoso.jena.driver.*;
public class VirtuosoSPARQLExample9 {
/**
* Executes a SPARQL query against a virtuoso url and prints results.
*/
public static void main(String[] args) {
String url;
if(args.length == 0)
url = "jdbc:virtuoso://localhost:1111";
else
url = args[0];
/* STEP 1 */
VirtGraph set = new VirtGraph (url, "dba", "dba");
/* STEP 2 */
String str = "CLEAR GRAPH <http://test1>";
VirtuosoUpdateRequest vur = VirtuosoUpdateFactory.create(str, set);
vur.exec();
str = "INSERT INTO GRAPH <http://test1> { <http://aa> <http://bb> 'cc' . <http://aa1> <http://bb> 123. }";
vur = VirtuosoUpdateFactory.create(str, set);
vur.exec();
/* Select all data in virtuoso */
Query sparql = QueryFactory.create("SELECT * FROM <http://test1> WHERE { ?s ?p ?o }");
VirtuosoQueryExecution vqe = VirtuosoQueryExecutionFactory.create (sparql, set);
ResultSet results = vqe.execSelect();
System.out.println("\nSELECT results:");
while (results.hasNext()) {
QuerySolution rs = results.nextSolution();
RDFNode s = rs.get("s");
RDFNode p = rs.get("p");
RDFNode o = rs.get("o");
System.out.println(" { " + s + " " + p + " " + o + " . }");
}
sparql = QueryFactory.create("DESCRIBE <http://aa> FROM <http://test1>");
vqe = VirtuosoQueryExecutionFactory.create (sparql, set);
Model model = vqe.execDescribe();
Graph g = model.getGraph();
System.out.println("\nDESCRIBE results:");
for (Iterator i = g.find(Node.ANY, Node.ANY, Node.ANY); i.hasNext();)
{
Triple t = (Triple)i.next();
System.out.println(" { " + t.getSubject() + " " +
t.getPredicate() + " " +
t.getObject() + " . }");
}
sparql = QueryFactory.create("CONSTRUCT { ?x <http://test> ?y } FROM <http://test1> WHERE { ?x <http://bb> ?y }");
vqe = VirtuosoQueryExecutionFactory.create (sparql, set);
model = vqe.execConstruct();
g = model.getGraph();
System.out.println("\nCONSTRUCT results:");
for (Iterator i = g.find(Node.ANY, Node.ANY, Node.ANY); i.hasNext();)
{
Triple t = (Triple)i.next();
System.out.println(" { " + t.getSubject() + " " +
t.getPredicate() + " " +
t.getObject() + " . }");
}
sparql = QueryFactory.create("ASK FROM <http://test1> WHERE { <http://aa> <http://bb> ?y }");
vqe = VirtuosoQueryExecutionFactory.create (sparql, set);
boolean res = vqe.execAsk();
System.out.println("\nASK results: "+res);
}
}
</verbatim>
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