/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package tdb.examples;
import com.hp.hpl.jena.query.* ;
import com.hp.hpl.jena.sparql.core.DatasetGraph ;
import com.hp.hpl.jena.tdb.TDBFactory ;
import com.hp.hpl.jena.tdb.transaction.DatasetGraphTransaction ;
/** Illustraion of working at the DatasetGraph level.
* Normally, applications work with {@link Dataset}.
* Occasionally, it's more convenient to work with the
* TDB-implemented DatasetGraph interface.
*/
public class ExTDB_Txn3
{
public static void main(String... argv)
{
DatasetGraphTransaction dsg = (DatasetGraphTransaction)TDBFactory.createDatasetGraph() ;
// Start READ transaction.
dsg.begin(ReadWrite.READ) ;
try
{
// Do some queries
String sparqlQueryString1 = "SELECT (count(*) AS ?count) { ?s ?p ?o }" ;
execQuery(sparqlQueryString1, dsg) ;
} finally
{
dsg.end() ;
}
}
public static void execQuery(String sparqlQueryString, DatasetGraph dsg)
{
// Add a datset wrapper to conform with the query interface.
// This shoudl not be very expensive.
Dataset dataset = DatasetFactory.create(dsg) ;
Query query = QueryFactory.create(sparqlQueryString) ;
QueryExecution qexec = QueryExecutionFactory.create(query, dataset) ;
try {
ResultSet results = qexec.execSelect() ;
for ( ; results.hasNext() ; )
{
QuerySolution soln = results.nextSolution() ;
int count = soln.getLiteral("count").getInt() ;
System.out.println("count = "+count) ;
}
} finally { qexec.close() ; }
}
}