public Graph generateGraph() {
try {
if (this.connection == null) {
this.connection = ds.getConnection();
} else if (this.connection.isClosed()) {
try {
this.connection.close();
} catch (SQLException e) {
// The connection will throw an "Already closed"
// SQLException that we need to catch. We need to
// make this extra call to .close() in order to make
// sure that the connection is returned to the pool.
// This depends on the particular behavior of version
// 1.4 of the Apache Commons connection pool library.
// Earlier versions threw the exception right away,
// making this impossible. Future versions may do the
// same.
}
this.connection = ds.getConnection();
}
Store store = SDBFactory.connectStore(connection, storeDesc);
return SDBFactory.connectNamedGraph(store, graphID);
} catch (SQLException e) {
String errMsg = "Unable to generate SDB graph";
log.error(errMsg, e);
throw new RuntimeException(errMsg, e);
}
}
public static void main(String... argv) {
String queryString = "SELECT * { ?s ?p ?o }";
Query query = QueryFactory.create(queryString);
Store store = SDBFactory.connectStore("sdb.ttl");
// Must be a DatasetStore to trigger the SDB query engine.
// Creating a graph from the Store, and adding it to a general
// purpose dataset will not necesarily exploit full SQL generation.
// The right answers will be obtained but slowly.
Dataset ds = DatasetStore.create(store);
QueryExecution qe = QueryExecutionFactory.create(query, ds);
try {
ResultSet rs = qe.execSelect();
ResultSetFormatter.out(rs);
} finally {
qe.close();
}
// Close the SDB conenction which also closes the underlying JDBC connection.
store.getConnection().close();
store.close();
}