jenajsonld.JsonLDWriter.java Source code

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Here is the source code for jenajsonld.JsonLDWriter.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jenajsonld;

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.*;
import java.util.Map.Entry;

import org.apache.jena.atlas.io.IO;
import org.apache.jena.atlas.iterator.Action;
import org.apache.jena.atlas.iterator.Iter;
import org.apache.jena.atlas.lib.Chars;
import org.apache.jena.iri.IRI;
import org.apache.jena.riot.Lang;
import org.apache.jena.riot.RDFFormat;
import org.apache.jena.riot.system.PrefixMap;
import org.apache.jena.riot.writer.WriterDatasetRIOTBase;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.github.jsonldjava.core.JSONLD;
import com.github.jsonldjava.core.JSONLDProcessingError;
import com.github.jsonldjava.core.Options;
import com.github.jsonldjava.utils.JSONUtils;
import com.hp.hpl.jena.graph.Graph;
import com.hp.hpl.jena.graph.Node;
import com.hp.hpl.jena.graph.Triple;
import com.hp.hpl.jena.sparql.core.DatasetGraph;
import com.hp.hpl.jena.sparql.util.Context;
import com.hp.hpl.jena.vocabulary.RDF;

class JsonLDWriter extends WriterDatasetRIOTBase {
    private final RDFFormat format;

    public JsonLDWriter(RDFFormat syntaxForm) {
        format = syntaxForm;
    }

    @Override
    public Lang getLang() {
        return format.getLang();
    }

    @Override
    public void write(Writer out, DatasetGraph dataset, PrefixMap prefixMap, String baseURI, Context context) {
        serialize(out, dataset, prefixMap, baseURI);
    }

    private boolean isPretty() {
        return RDFFormat.PRETTY.equals(format.getVariant());
    }

    @Override
    public void write(OutputStream out, DatasetGraph dataset, PrefixMap prefixMap, String baseURI,
            Context context) {
        Writer w = new OutputStreamWriter(out, Chars.charsetUTF8);
        write(w, dataset, prefixMap, baseURI, context);
        IO.flush(w);
    }

    private void serialize(Writer writer, DatasetGraph dataset, PrefixMap prefixMap, String baseURI) {
        final Map<String, Object> ctx = new LinkedHashMap<String, Object>();
        addProperties(ctx, dataset.getDefaultGraph());
        addPrefixes(ctx, prefixMap);

        try {
            Object obj = JSONLD.fromRDF(dataset, new JenaRDF2JSONLD());
            Options opts = new Options();
            opts.graph = false;
            opts.addBlankNodeIDs = false;
            opts.useRdfType = true;
            opts.useNativeTypes = true;
            opts.skipExpansion = false;
            opts.compactArrays = true;
            opts.keepFreeFloatingNodes = false;
            Map<String, Object> localCtx = new HashMap<>();
            localCtx.put("@context", ctx);

            //AT A MINIMUM
            if (false)
                obj = JSONLD.simplify(obj, opts);
            else
                // Unclear as to the way to set better printing.
                obj = JSONLD.compact(obj, localCtx);

            if (isPretty())
                JSONUtils.writePrettyPrint(writer, obj);
            else
                JSONUtils.write(writer, obj);
        } catch (JSONLDProcessingError e) {
            e.printStackTrace();
        } catch (JsonGenerationException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void addPrefixes(Map<String, Object> ctx, PrefixMap prefixMap) {
        Map<String, IRI> pmap = prefixMap.getMapping();
        for (Entry<String, IRI> e : pmap.entrySet()) {
            ctx.put(e.getKey(), e.getValue().toString());
        }

    }

    private void addProperties(final Map<String, Object> ctx, Graph graph) {
        // Add some properties directly so it becomes "localname": ....
        final Set<String> dups = new HashSet<>();
        Action<Triple> x = new Action<Triple>() {
            @Override
            public void apply(Triple item) {
                Node p = item.getPredicate();
                if (p.equals(RDF.type.asNode()))
                    return;
                String x = p.getLocalName();
                if (dups.contains(x))
                    return;

                if (ctx.containsKey(x)) {
                    // Check different URI
                    //                    pmap2.remove(x) ;
                    //                    dups.add(x) ;  
                } else {
                    Map<String, Object> x2 = new LinkedHashMap<String, Object>();
                    x2.put("@id", p.getURI());
                    x2.put("@type", "@id");
                    ctx.put(x, x2);
                }
            }
        };

        Iter.iter(graph.find(null, null, null)).apply(x);

    }
}