Variante 1

La siguiente muestra cargará un InputStream con datos comprimidos en un repositorio rdf en memoria. El formato comprimido es compatible directamente con rdf4j. Cada declaración número 100000 se imprimirá en stdout usando RepositoryConnectionListenerAdapter.

import java.io.InputStream;

import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Resource;
import org.eclipse.rdf4j.model.Value;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.repository.event.base.NotifyingRepositoryConnectionWrapper;
import org.eclipse.rdf4j.repository.event.base.RepositoryConnectionListenerAdapter;
import org.eclipse.rdf4j.repository.sail.SailRepository;
import org.eclipse.rdf4j.rio.RDFFormat;
import org.eclipse.rdf4j.sail.memory.MemoryStore;

public class MyTripleStore {

    Repository repo;

    /**
     * Creates an inmemory triple store
     * 
     */
    public MyTripleStore() {
        repo = new SailRepository(new MemoryStore());
        repo.initialize();
    }

    /**
     * @param in gzip compressed data on an inputstream
     * @param format the format of the streamed data
     */
    public void loadZippedFile(InputStream in, RDFFormat format) {
        System.out.println("Load zip file of format " + format);
        try (NotifyingRepositoryConnectionWrapper con =
                new NotifyingRepositoryConnectionWrapper(repo, repo.getConnection());) {
            RepositoryConnectionListenerAdapter myListener =
                    new RepositoryConnectionListenerAdapter() {
                        private long count = 0;
                        @Override
                        public void add(RepositoryConnection arg0, Resource arg1, IRI arg2, 
                                         Value arg3, Resource... arg4) {
                            count++;
                            if (count % 100000 == 0)
                                    System.out.println("Add statement number " + count + "\n" 
                                    + arg1+ " " + arg2 + " " + arg3);
                        }
                    };
            con.addRepositoryConnectionListener(myListener);
            con.add(in, "", format);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

Variante 2

Esta variante implementa un AbstractRDFHandler para proporcionar el informe.

import java.io.InputStream;

import org.eclipse.rdf4j.model.Statement;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.repository.sail.SailRepository;
import org.eclipse.rdf4j.repository.util.RDFInserter;
import org.eclipse.rdf4j.repository.util.RDFLoader;
import org.eclipse.rdf4j.rio.RDFFormat;
import org.eclipse.rdf4j.rio.helpers.AbstractRDFHandler;
import org.eclipse.rdf4j.sail.memory.MemoryStore;

public class MyTripleStore {
    Repository repo;

    /**
      * Creates an inmemory triple store
      * 
      */
    public MyTripleStore() {
        repo = new SailRepository(new MemoryStore());
        repo.initialize();
   }

    /**
     * @param in gzip compressed data on an inputstream
     * @param format the format of the streamed data
     */
    public void loadZippedFile1(InputStream in, RDFFormat format) {
        try (RepositoryConnection con = repo.getConnection()) {
            MyRdfInserter inserter = new MyRdfInserter(con);
            RDFLoader loader =
                    new RDFLoader(con.getParserConfig(), con.getValueFactory());
            loader.load(in, "", RDFFormat.NTRIPLES, inserter);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    class MyRdfInserter extends AbstractRDFHandler {
        RDFInserter rdfInserter;
        int count = 0;

        public MyRdfInserter(RepositoryConnection con) {
            rdfInserter = new RDFInserter(con);
        }

        @Override
        public void handleStatement(Statement st) {
            count++;
            if (count % 100000 == 0)
                System.out.println("Add statement number " + count + "\n"
                        + st.getSubject().stringValue() + " "
                        + st.getPredicate().stringValue() + " "
                        + st.getObject().stringValue());
            rdfInserter.handleStatement(st);
        }
    }
}

Aquí está, cómo llamar al código

MyTripleStore ts = new MyTripleStore();
ts.loadZippedFile(new FileInputStream("your-ntriples-zipped.gz"),
            RDFFormat.NTRIPLES);