AGSparqlSelect.java
package com.franz.agbase.examples;
import com.franz.agbase.*;
/**
* Demonstrates issuing a simple SPARQL SELECT query and showing results.
*
*/
public class AGSparqlSelect {
public static void main(String[] args) throws AllegroGraphException {
// Connect to server, which must already be running.
AllegroGraphConnection ags = new AllegroGraphConnection();
try {
ags.enable();
} catch (Exception e) {
throw new AllegroGraphException("Server connection problem", e);
}
// Create fresh triple-store for this example.
AllegroGraph ts = ags.renew("sparqlselect", AGPaths.TRIPLE_STORES);
// Register a namespace
ts.registerNamespace("ex","http://example.org/");
// Add a few triples to the store
ts.addStatement("!ex:a","!ex:p", "!ex:b");
ts.addStatement("!ex:b","!ex:p", "!ex:c");
// A simple SPARQL SELECT query
String query = "SELECT * {?s ?p ?o}";
// Set up the SPARQLQuery object
SPARQLQuery sq = new SPARQLQuery();
sq.setTripleStore(ts);
sq.setQuery(query);
// Do the SELECT query and show results
doSparqlSelect(sq);
}
/**
* A convenience method for showing SPARQL SELECT queries to the user, it prints
* the given query and its results.
*
* @param sq a SPARQLQuery object with any optional parameters set.
*
* @throws AllegroGraphException
*/
public static void doSparqlSelect(SPARQLQuery sq) throws AllegroGraphException {
if (sq.isIncludeInferred()) {
System.out.println("\nQuery (with RDFS++ inference):");
} else {
System.out.println("\nQuery:");
}
System.out.println(" " + sq.getQuery());
ValueSetIterator it = sq.select();
AGUtils.showResults(it);
}
}
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