uk.ac.ceh.components.vocab.sparql.SparqlVocabulary Maven / Gradle / Ivy

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package uk.ac.ceh.components.vocab.sparql;

import com.sun.jersey.api.client.*;
import java.util.*;
import uk.ac.ceh.components.vocab.*;

public class SparqlVocabulary implements Vocabulary {
    private static final String HARVEST_QUERY = 
    "PREFIX skos: SELECT ?concept ?prefLabel WHERE { ?concept a skos:Concept ; skos:prefLabel ?prefLabel . }";
     
    private final WebResource resource;
    private final String url;
    private final String name;
    private final String query;
    
    public SparqlVocabulary(String url, String name) {
        this(url, name, HARVEST_QUERY);
    }
    
    public SparqlVocabulary(String url, String name, String query) {
        this.resource = Client.create().resource(url);
        this.url = url;
        this.name = name;
        this.query = query;
    }
    
    @Override
    public String getUrl() {
        return url;
    }
    
    @Override
    public String getName() {
        return name;
    }

    @Override
    public List getAllConcepts() throws VocabularyException {
        try {
            SparqlResponse sparql = resource.queryParam("query", query)
                                            .accept("application/sparql-result+xml")
                                            .get(SparqlResponse.class);
            return transformResponse(sparql);
        }
        catch(UniformInterfaceException | ClientHandlerException ex) {
            throw new VocabularyException("Unable to get concepts for sparql vocab", ex);
        }
    }
    
    private List transformResponse(SparqlResponse sparql) {
        List toReturn = new ArrayList<>();
        for(SparqlResult result : sparql.getResults()) {
            SparqlConcept toAdd = new SparqlConcept();
            //Sparql returns a list of binings for each result, we need to flatten 
            //this list to create a single SolrOntologyIndex (uri,term pair)
            //which we can then push into solr
            for(SparqlResult.Binding binding: result.getBindings()) {
                if(binding.getUri() != null) {
                    toAdd.setUri(binding.getUri());
                }
                if(binding.getTerm() != null) {
                    toAdd.setTerm(binding.getTerm());
                }
                toReturn.add(toAdd);
            }
        }
        return toReturn;
    }
}