javafilesparqljenafuseki

write result of SPARQL to file in java

I use fuseki server as embedded server in java and I get SPARQL results with following piece of code:

public static void execSelectAndPrint(FileWriter fw, String serviceURI, String query) throws IOException {
    QueryExecution q = QueryExecutionFactory.sparqlService(serviceURI,query);
    ResultSet results = q.execSelect();
    ResultSetFormatter.outputAsCSV(System.out, results);
    while (results.hasNext()) {
        QuerySolution soln = results.nextSolution();
        RDFNode x = soln.get("x");
        System.out.println(x);
        fw.append(x.toString());        
    }
    fw.close();
}

it prints results to console correctly but it can write to file. I want to write result of SPARQL query to a csv file.

Solution

  • Java Writers can produce problems with character translation which is why the API prefers OutputStream and so using FileOutputStream will work.

    Otherwise, output to bytes using ByteArrayOutputStream, convert to a string and write the string.

    But be careful about character sets. Most SPARQL related formats are UTF-8, not the platform native character set.