package org.ontoware.semweb4j.lessons.lesson2;
import org.ontoware.rdf2go.RDF2Go;
import org.ontoware.rdf2go.exception.ModelRuntimeException;
import org.ontoware.rdf2go.model.Model;
import org.ontoware.rdf2go.model.node.Node;
import org.ontoware.rdf2go.model.node.PlainLiteral;
import org.ontoware.rdf2go.model.node.Resource;
import org.ontoware.rdf2go.model.node.URI;
import org.ontoware.rdf2go.vocabulary.XSD;
public class Step7 {
private static Model model;
private static URI hasTag;
private static void init() throws ModelRuntimeException {
model = RDF2Go.getModelFactory().createModel();
model.open();
}
public static void tag(Resource resource, Node tag) throws ModelRuntimeException {
model.addStatement(resource, hasTag, tag);
}
public static void main(String[] args) throws ModelRuntimeException {
init();
// creating URIs
// persons
URI max = model.createURI("http://xam.de/foaf.rdf.xml#i");
URI konrad = model.createURI("http://example.com/persons#konrad");
URI guido = model.createURI("http://example.com/persons#guido");
URI james = model.createURI("http://example.com/persons#james");
// relations
URI hasName = model.createURI("http://xmlns.com/foaf/0.1/#term_name");
URI hasAge = model.createURI("http://example.com/relations#age");
hasTag = model.createURI("http://example.com/relations#hasTag");
// tags
PlainLiteral tagJava = model.createPlainLiteral("Java");
PlainLiteral tagPython = model.createPlainLiteral("Python");
PlainLiteral tagComputers = model.createPlainLiteral("Computers");
// adding statements
// naming
model.addStatement(max, hasName, "Max Völkel");
model.addStatement(konrad, hasName, "Konrad Völkel");
model.addStatement(guido, hasName, "Guido van Rossum");
model.addStatement(james, hasName, "James Gosling");
// a typed property, age
model.addStatement(konrad, hasAge, model.createDatatypeLiteral("19", XSD._integer));
model.addStatement(max, hasAge, model.createDatatypeLiteral("29", XSD._integer));
// tagging
tag(max, tagJava);
tag(james, tagJava);
tag(konrad, tagJava);
tag(konrad, tagPython);
tag(guido, tagPython);
// simple SPARQL ASK
System.out.println("Query 1:");
// ask if max is subject or object of any statement
String queryString = "ASK { { "+max.toSPARQL()+" ?p ?o } UNION { ?s ?p "+max.toSPARQL()+" } }";
boolean result = model.sparqlAsk(queryString);
if(result) {
System.out.println(max+" is in the graph");
}
// another SPARQL ASK
System.out.println("Query 2:");
// ask if any resource is tagged with tagComputers
queryString = "ASK { ?resource <"+hasTag+"> "+tagComputers.toSPARQL()+" }";
if(!model.sparqlAsk(queryString)) {
System.out.println("nothing is tagged with "+tagComputers);
}
}
}