/**
* 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.Dataset ;
import com.hp.hpl.jena.query.Query ;
import com.hp.hpl.jena.query.QueryExecution ;
import com.hp.hpl.jena.query.QueryExecutionFactory ;
import com.hp.hpl.jena.query.QueryFactory ;
import com.hp.hpl.jena.query.QuerySolution ;
import com.hp.hpl.jena.query.ReadWrite ;
import com.hp.hpl.jena.query.ResultSet ;
import com.hp.hpl.jena.tdb.TDBFactory ;
/** Example of a READ transaction. */
public class ExTDB_Txn1
{
public static void main(String... argv)
{
String directory = "MyDatabases/DB1" ;
Dataset dataset = TDBFactory.createDataset(directory) ;
// Start READ transaction.
// No updates or changes to the dataset are possible while this
// dataset is used for a read transaction.
// An application can have other Datasets, in the same JVM,
// tied to the same TDB database performing read or write
// transactions concurrently.
dataset.begin(ReadWrite.READ) ;
try
{
// Do some queries
String sparqlQueryString1 = "SELECT (count(*) AS ?count) { ?s ?p ?o }" ;
execQuery(sparqlQueryString1, dataset) ;
String sparqlQueryString2 = "SELECT * { ?s ?p ?o }" ;
execQuery(sparqlQueryString2, dataset) ;
// Can also call dataset.abort() or dataset.commit() here
} finally
{
// Notify the end of the READ transaction.
// Any use of dataset.abort() or dataset.commit() or dataset.end()
// .end() can be called multiple times for the same .begin(READ)
dataset.end() ;
}
}
public static void execQuery(String sparqlQueryString, Dataset dataset)
{
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() ; }
}
}