import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
@Override public void testContainsNode() {
  Graph g = getGraph();
  graphAdd( g, "a P b; _c P1 _d; a P2 12" );
  QueryHandler qh = g.queryHandler();
  assertTrue( qh.containsNode( node( "a" ) ) );
  assertTrue( qh.containsNode( node( "P" ) ) );
  assertTrue( qh.containsNode( node( "b" ) ) );
  assertTrue( qh.containsNode( node( "_c" ) ) );
  assertTrue( qh.containsNode( node( "_d" ) ) );
  assertTrue( qh.containsNode( node( "P2" ) ) );
  assertTrue( qh.containsNode( node( "12" ) ) );
  /* */
  assertFalse( qh.containsNode( node( "x" ) ) );
  assertFalse( qh.containsNode( node( "_y" ) ) );
  assertFalse( qh.containsNode( node( "99" ) ) );
}
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
@Override
public QueryHandler queryHandler() {
	checkOpen();
	return new D2RQQueryHandler(this);
}
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
@Override 
public QueryHandler queryHandler() {
  return queryHandler;
}
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
@Override
  public QueryHandler queryHandler()
{
if (q == null) q = new DBQueryHandler( this);
return q;
}
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
@Override public QueryHandler queryHandler()
{ return optimiseOne() ? singleGraphQueryHandler() : super.queryHandler(); }
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
private QueryHandler singleGraphQueryHandler()
{ return (m_subGraphs.get( 0 )).queryHandler(); }
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
public QueryHandler queryHandler() {
	checkMappingFileChanged();
	return this.datasetGraph.getDefaultGraph().queryHandler();
}
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
/**
 * Returns a QueryHandler for this graph.
 * The query handler class can be set by the mapping.
 * It then must have exact constructor signature QueryHandler(Graph)
 * For some reasons, Java does not allow to call getConstructor(GraphD2RQ.class)
 * on SimpleQueryHandler class.
 */
@Override
public QueryHandler queryHandler() {
	checkOpen();
	return new D2RQQueryHandler(this);
}
 

import com.hp.hpl.jena.graph.query.QueryHandler; //导入依赖的package包/类
/**
 * <p>Method that returns the underlying query handler for this D2RQ++ graph</p>
 * @return a QueryHandler representing this D2RQ++ graph
 * 
 * @see de.fuberlin.wiwiss.d2rq.GraphD2RQ#queryHandler()
 */
public QueryHandler queryHandler() 
{
	checkOpen();
	return new D2RQRWQueryHandler(this, dataset);
}