Selecting multiple results from query

问题

I have this query for example which returns four results. What I am doing with this code is selecting one of those results through an integer, so that I can do another query for it later. What I have been trying to do, and haven't been able to yet, is select more than just one result, so that I can reuse them separately. For example this query would return:

RESULT A
RESULT B
RESULT C
RESULT D

I can type, for example, 1 in the console and get that value in a string and reuse it. What is a convenient way, for example, to type 1,2,3 and get these values added to a String array?

public static String[] path = new String[30];

String queryString =
    "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> " +        
    "PREFIX owl: <http://www.w3.org/2002/07/owl#> " +
    "PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> " +
    "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> " +
    "PREFIX bio: <http://www.semanticweb.org/vassilis/ontologies/2013/5/Onto#> " +

    " SELECT DISTINCT ?Animal " +
    " WHERE { ?Animal rdf:type bio:Animal } " ;

Query query = QueryFactory.create(queryString);
QueryExecution qe= QueryExecutionFactory.create(query, model);
ResultSet resultset = qe.execSelect();
ResultSet results = ResultSetFactory.copyResults(resultset); 
ResultSet results2 = ResultSetFactory.copyResults(results);
ResultSetFormatter.out(System.out, results, query);

List<QuerySolution> e = ResultSetFormatter.toList(results2);
String next;
System.out.println("Select Animal: ");

next = user_input.next( );

int i = Integer.parseInt(next);
QuerySolution e1 = e.get(i);
RDFNode rd = e1.get("");  
String rds = rd.toString();
String phrase = rds; 
String delims = "[#]";
String[] tokens = phrase.split(delims); 
newStr = tokens[1].replaceAll("_","");
path[1] = newStr;

Edit, updated code:

final Scanner input = new Scanner( System.in );          
String selec2;
selec2 = input.next();

final String[] indices = selec2.split("\\s*,\\s*");

final List<QuerySolution> selectedSolutions = new ArrayList<QuerySolution>( indices.length ) {{
        final List<QuerySolution> solutions = ResultSetFormatter.toList( results2 );
        for ( final String index : indices ) {
            add( solutions.get( Integer.valueOf( index )));
        }
    }};

System.out.println( "== Selected Solutions ==" );
System.out.println(selectedSolutions);

int k = 0;
while (input.hasNext()) {
    int i = Integer.parseInt(selec2);
    QuerySolution e1 = selectedSolutions.get(i);

    RDFNode rd = e1.get("Ani");  
    String rds = rd.toString();
    String phrase = rds;  
    String delims = "[#]";
    String[] tokens = phrase.split(delims); 
    newStr = tokens[1].replaceAll("_", "");
    path[k]= newStr;
    k++;
}
System.out.println(path);

回答1:

When you get a ResultSet, you can only use its solutions once, and then they're consumed. So, in order to iterate over the solutions multiple times, you need to copy the results using, e.g., ResultSetFactory.copyResults. Then you can access the query solutions multiple times. You can take an input string like "1,2,3" and get a string array ["1", "2", "3"] using something like the answer to

how to get numbers separated by comma entered in a line into an array in Java

Then you can iterate through the indices and select just the query solutions that you want and add them to a list. For instance:

import java.io.ByteArrayInputStream;
import java.util.ArrayList;
import java.util.List;

import com.hp.hpl.jena.query.QueryExecutionFactory;
import com.hp.hpl.jena.query.QuerySolution;
import com.hp.hpl.jena.query.ResultSet;
import com.hp.hpl.jena.query.ResultSetFactory;
import com.hp.hpl.jena.query.ResultSetFormatter;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;

public class QuerySolutionsFromIndicesExample {

    final static String modelText = "" +
            "@prefix bio: <http://www.semanticweb.org/vassilis/ontologies/2013/5/Onto#>.\n" +
            "@prefix ex: <http://example.org/>.\n" +
            "\n" +
            "ex:Giraffe a bio:Animal .\n" +
            "ex:Dog a bio:Animal .\n" +
            "ex:Cat a bio:Animal . \n" +
            "ex:WoollyMammoth a bio:Animal.\n" +
            "";

    final static String sparqlQuery = "" +
            "prefix bio: <http://www.semanticweb.org/vassilis/ontologies/2013/5/Onto#>\n" +
            "\n" +
            "select ?animal where {\n" +
            "  ?animal a bio:Animal\n" +
            "}\n" +
            "";

    public static void main(String[] args) {
        final Model model = ModelFactory.createDefaultModel();
        model.read( new ByteArrayInputStream( modelText.getBytes()), null, "TTL" );

        final ResultSet results = ResultSetFactory.copyResults( QueryExecutionFactory.create( sparqlQuery, model ).execSelect() );

        System.out.println( "== All Solutions ==" );
        ResultSetFormatter.out( results );

        // based on https://stackoverflow.com/q/10565335/1281433
        final String input = "0,3"; 
        final String[] indices = input.split("\\s*,\\s*");

        final List<QuerySolution> selectedSolutions = new ArrayList<QuerySolution>( indices.length ) {{
            final List<QuerySolution> solutions = ResultSetFormatter.toList( results );
            for ( final String index : indices ) {
                add( solutions.get( Integer.valueOf( index )));
            }
        }};

        System.out.println( "== Selected Solutions ==" );
        System.out.println( selectedSolutions );
    }
}

来源：https://stackoverflow.com/questions/18838995/selecting-multiple-results-from-query

标签

java

sparql

jena