`/*
* (c) Copyright 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
* All rights reserved.
* [See end of file]
*/
package arq.examples;
// The ARQ application API.
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.query.*;
import com.hp.hpl.jena.rdf.model.*;
import com.hp.hpl.jena.sparql.core.Var;
import com.hp.hpl.jena.sparql.expr.E_Regex;
import com.hp.hpl.jena.sparql.expr.Expr;
import com.hp.hpl.jena.sparql.expr.ExprVar;
import com.hp.hpl.jena.sparql.syntax.ElementFilter;
import com.hp.hpl.jena.sparql.syntax.ElementGroup;
import com.hp.hpl.jena.sparql.util.IndentedWriter;
import com.hp.hpl.jena.vocabulary.DC;
/** Example : Build a query with a filter programmatically.
* Note: it is often better to build and execute an algebra expression. See other examples.
*
* @author Andy Seaborne
*/
public class ExProg2
{
static public final String NL = System.getProperty("line.separator") ;
public static void main(String[] args)
{
Model model = createModel() ;
Query query = QueryFactory.make() ;
query.setQueryType(Query.QueryTypeSelect) ;
// See also ExProg1
ElementGroup elg = new ElementGroup() ;
Var varTitle = Var.alloc("title") ;
Var varX = Var.alloc("x") ;
Triple t1 = new Triple(varX, DC.title.asNode(), varTitle) ;
elg.addTriplePattern(t1) ;
// Adds a filter. Need to wrap variable in a NodeVar.
Expr expr = new E_Regex(new ExprVar(varTitle), "sparql", "i") ;
ElementFilter filter = new ElementFilter(expr) ;
elg.addElementFilter(filter) ;
// Attach the group to query.
query.setQueryPattern(elg) ;
// Choose what we want - SELECT ?title
query.addResultVar(varTitle) ;
// Print query with line numbers
// Prefix mapping just helps serialization
query.getPrefixMapping().setNsPrefix("dc" , DC.getURI()) ;
query.serialize(new IndentedWriter(System.out,true)) ;
System.out.println() ;
QueryExecution qexec = QueryExecutionFactory.create(query, model) ;
try {
// Assumption: it's a SELECT query.
ResultSet rs = qexec.execSelect() ;
// The order of results is undefined.
System.out.println("Titles: ") ;
for ( ; rs.hasNext() ; )
{
QuerySolution rb = rs.nextSolution() ;
// Get title - variable names do not include the '?' (or '$')
RDFNode x = rb.get("title") ;
// Check the type of the result value
if ( x instanceof Literal )
{
Literal titleStr = (Literal)x ;
System.out.println(" "+titleStr) ;
}
else
System.out.println("Strange - not a literal: "+x) ;
}
}
finally
{
// QueryExecution objects should be closed to free any system resources
qexec.close() ;
}
}
public static Model createModel()
{
Model model = ModelFactory.createDefaultModel() ;
Resource r1 = model.createResource("http://example.org/book#1") ;
Resource r2 = model.createResource("http://example.org/book#2") ;
Resource r3 = model.createResource("http://example.org/book#3") ;
r1.addProperty(DC.title, "SPARQL - the book")
.addProperty(DC.description, "A book about SPARQL") ;
r2.addProperty(DC.title, "Advanced techniques for SPARQL") ;
r3.addProperty(DC.title, "Jena - an RDF framework for Java")
.addProperty(DC.description, "A book about Jena") ;
return model ;
}
}
/*
* (c) Copyright 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/`