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JSON-LD Java integration module for Sesame
There is a newer version: 0.5.1
/**
 * 
 */
package com.github.jsonldjava.impl;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.Map;

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.JSONLDProcessor;
import com.github.jsonldjava.core.Options;
import com.github.jsonldjava.utils.JSONUtils;

import org.openrdf.model.Model;
import org.openrdf.model.Statement;
import org.openrdf.model.impl.LinkedHashModel;
import org.openrdf.rio.RDFFormat;
import org.openrdf.rio.RDFHandlerException;
import org.openrdf.rio.RDFWriter;
import org.openrdf.rio.helpers.BasicParserSettings;
import org.openrdf.rio.helpers.BasicWriterSettings;
import org.openrdf.rio.helpers.JSONLDMode;
import org.openrdf.rio.helpers.JSONLDSettings;
import org.openrdf.rio.helpers.RDFWriterBase;
import org.openrdf.rio.helpers.StatementCollector;


/**
 * @author Peter Ansell [email protected]
 * 
 */
public class SesameJSONLDWriter extends RDFWriterBase implements RDFWriter {

    private Model model = new LinkedHashModel();

    private StatementCollector statementCollector = new StatementCollector(
	    model);

    private Writer writer;

    /**
     * Create a SesameJSONLDWriter using a java.io.OutputStream
     * 
     * @param outputStream
     */
    public SesameJSONLDWriter(OutputStream outputStream) {
	this(new BufferedWriter(new OutputStreamWriter(outputStream,
		Charset.forName("UTF-8"))));
    }

    /**
     * Create a SesameJSONLDWriter using a java.io.Writer
     */
    public SesameJSONLDWriter(Writer nextWriter) {
	writer = nextWriter;
    }

    @Override
    public void handleNamespace(String prefix, String uri)
	    throws RDFHandlerException {
	model.setNamespace(prefix, uri);
    }

    @Override
    public void startRDF() throws RDFHandlerException {
	statementCollector.clear();
	model.clear();
    }

    @Override
    public void endRDF() throws RDFHandlerException {
	SesameRDFParser serialiser = new SesameRDFParser();
	try {
	    Object output = JSONLD.fromRDF(model, serialiser);

	    JSONLDMode mode = getWriterConfig().get(JSONLDSettings.JSONLD_MODE);

	    Options opts = new Options();
	    opts.addBlankNodeIDs = getWriterConfig().get(
		    BasicParserSettings.PRESERVE_BNODE_IDS);
	    opts.useRdfType = getWriterConfig()
		    .get(JSONLDSettings.USE_RDF_TYPE);
	    opts.useNativeTypes = getWriterConfig().get(
		    JSONLDSettings.USE_NATIVE_TYPES);
	    //opts.optimize = getWriterConfig().get(JSONLDSettings.OPTIMIZE);

	    if (mode == JSONLDMode.EXPAND) {
		output = JSONLD.expand(output, opts);
	    }
	    // TODO: Implement inframe in JSONLDSettings
	    Object inframe = null;
	    if (mode == JSONLDMode.FLATTEN) {
		output = JSONLD.frame(output, (Map) inframe, opts);
	    }
	    if (mode == JSONLDMode.COMPACT) {
		output = JSONLD.simplify(output, opts);
	    }
	    if (getWriterConfig().get(BasicWriterSettings.PRETTY_PRINT)) {
		JSONUtils.writePrettyPrint(writer, output);
	    } else {
		JSONUtils.write(writer, output);
	    }

	} catch (JSONLDProcessingError e) {
	    throw new RDFHandlerException("Could not render JSONLD", e);
	} catch (JsonGenerationException e) {
	    throw new RDFHandlerException("Could not render JSONLD", e);
	} catch (JsonMappingException e) {
	    throw new RDFHandlerException("Could not render JSONLD", e);
	} catch (IOException e) {
	    throw new RDFHandlerException("Could not render JSONLD", e);
	}
    }

    @Override
    public void handleStatement(Statement st) throws RDFHandlerException {
	statementCollector.handleStatement(st);
    }

    @Override
    public void handleComment(String comment) throws RDFHandlerException {
    }

    @Override
    public RDFFormat getRDFFormat() {
	return RDFFormat.JSONLD;
    }

}