jena-arq/src-examples/arq/examples/riot/ExRIOT7_AddNewWriter.java

/**
 * 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 arq.examples.riot;

import java.io.OutputStream ;
import java.io.Writer ;

import org.apache.jena.atlas.io.IndentedWriter ;
import org.apache.jena.atlas.logging.LogCtl ;
import org.apache.jena.graph.Graph ;
import org.apache.jena.rdf.model.Model ;
import org.apache.jena.riot.* ;
import org.apache.jena.riot.adapters.RDFWriterRIOT ;
import org.apache.jena.riot.system.PrefixMap ;
import org.apache.jena.riot.system.RiotLib ;
import org.apache.jena.riot.writer.WriterGraphRIOTBase ;
import org.apache.jena.sparql.sse.SSE ;
import org.apache.jena.sparql.util.Context ;

/** Example of registering a new writer with RIOT */
public class ExRIOT7_AddNewWriter
{
    static { LogCtl.setLogging(); }
    
    // See also ExRIOT6_AddReader
    public static void main(String[] args)
    {
        System.out.println("## Example of a registering a new language with RIOT for writing") ; 
        System.out.println() ;
        
        // Register the language
        Lang lang = LangBuilder.create("SSE", "text/x-sse").addFileExtensions("rsse").build() ;
        RDFLanguages.register(lang) ;

        // Create format and register the association of language and default format.
        // We are creating only one format here but in geenral theer can be variants
        // (e.g. TURTLE - pretty printed or streamed) 
        RDFFormat format = new RDFFormat(lang) ;
        RDFWriterRegistry.register(lang, format)  ;
        
        // Register the writer factory
        RDFWriterRegistry.register(format, new SSEWriterFactory()) ;

        // ---- Use the register writer
        Model model = RDFDataMgr.loadModel("/home/afs/tmp/D.ttl") ;
        // Write
        System.out.println("## Write by format") ;
        RDFDataMgr.write(System.out, model, format) ;
        System.out.println() ;
        System.out.println("## Write by language") ;
        RDFDataMgr.write(System.out, model, lang) ;
        
        // ---- Or use Model.write
        System.out.println("## Write by Model.write") ;
        model.write(System.out, "SSE") ;
    }
    
    static class SSEWriterFactory implements WriterGraphRIOTFactory
    {
        @Override
        public WriterGraphRIOT create(RDFFormat syntaxForm)
        {
            return new SSEWriter() ;
        }
    }
    
    static class SSEWriter extends WriterGraphRIOTBase
    {
        // Ignore externally provided prefix map and baseURI
        @Override
        public void write(OutputStream out, Graph graph, PrefixMap prefixMap, String baseURI, Context context)
        {
            SSE.write(out, graph) ;
        }

        @Override
        public Lang getLang()   { return  RDFLanguages.contentTypeToLang("text/x-sse") ; }

        @Override
        public void write(Writer out, Graph graph, PrefixMap prefixMap, String baseURI, Context context)
        {
            // Writers are discouraged : just hope the charset is UTF-8.
            IndentedWriter x = RiotLib.create(out) ;
            SSE.write(x, graph) ;
        }
    }

    // Model.write adapter - must be public.
    public static class RDFWriterSSE extends RDFWriterRIOT { public RDFWriterSSE() { super("SSE") ; } } 
}