Jena NoReaderForLangException：猫头鹰

Question

我的问题是 Jena，当我使用 Turtle Ontolgy 时，它工作正常，当我使用任何其他本体（如 OWL 或 RDFS）时，它显示相同的错误

线程“main”中的异常 com.hp.hpl.jena.shared.NoReaderForLangException： owl 在 com.hp.hpl.jena.rdf.model.impl.RDFReaderFImpl.getReader(RDFReaderFImpl.java:110) 在 com.hp.hpl.jena.rdf.model.impl.ModelCom.read(ModelCom.java:225) 在com.hp.hpl.jena.ontology.impl.OntModelImpl.read(OntModelImpl.java:2169) 在 symmenticweb.SymenticWeb.main(SymenticWeb.java:109) Java 结果：1

第 109 行是 model.read(inputStream, null, inputFileFormat);

我的代码是

package symenticweb;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Iterator;

import org.mindswap.pellet.jena.PelletReasonerFactory;

import com.hp.hpl.jena.ontology.Individual;
import com.hp.hpl.jena.ontology.OntModel;
import com.hp.hpl.jena.ontology.OntModelSpec;
import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.Statement;
import com.hp.hpl.jena.rdf.model.StmtIterator;
import com.hp.hpl.jena.reasoner.Reasoner;
import com.hp.hpl.jena.reasoner.ValidityReport;
import com.hp.hpl.jena.util.iterator.ExtendedIterator;

public class SymenticWeb
{
   /**
    * This program takes 4 parameters an input file name 
    * an output file name an input file format a reasoning 
    * level {RDFS, OWL-DL}
    */
   public static void main(String[] args)
   {
       //validate the program arguments
//      if(args.length != 4) 
//      {   
//         System.err.println("Usage: java InferenceExample "
//            + "<input file> <input format> <output file> "
//            + "<none|rdfs|owl>");
//         return;
//      }

      String inputFileName;
       inputFileName = "C:\\Users\\Harjinder\\Documents\\NetBeansProjects\\SymenticWeb\\src\\test\\abc.owl";
      String inputFileFormat = "owl";
      String outputFileName = "C:\\New folder\\abc.txt";
      String reasoningLevel = "none";

      //create an input stream for the input file
      FileInputStream inputStream = null;
      PrintWriter writer = null;
      try 
      {
         inputStream = new FileInputStream(inputFileName);
      } catch (FileNotFoundException e) {
         System.err.println("'" + inputFileName 
            + "' is an invalid input file.");
         return;
      }

      //create an output print writer for the results
      try 
      {
         writer = new PrintWriter(outputFileName);
      } catch (FileNotFoundException e) {
         System.err.println("'" + outputFileName 
            + "' is an invalid output file.");
         return;
      }

      //create the appropriate jena model
      OntModel model = null;
      if("none".equals(reasoningLevel.toLowerCase()))
      {
         /*
          * "none" is jena model with OWL_DL
          * ontologies loaded and no inference enabled
          */
         model = ModelFactory.createOntologyModel(
            OntModelSpec.OWL_DL_MEM);
      }
      else if("rdfs".equals(reasoningLevel.toLowerCase()))
      {
         /*
          * "rdfs" is jena model with OWL_DL
          * ontologies loaded and RDFS inference enabled 
          */
         model = ModelFactory.createOntologyModel(
            OntModelSpec.OWL_DL_MEM_RDFS_INF); 
      }
      else if("owl".equals(reasoningLevel.toLowerCase()))
      {
         /*
          * "owl" is jena model with OWL_DL ontologies
          * wrapped around a pellet-based inference model
          */
         Reasoner reasoner = 
            PelletReasonerFactory.theInstance().create();
         Model infModel = ModelFactory.createInfModel(
            reasoner, ModelFactory.createDefaultModel());
         model = ModelFactory.createOntologyModel(
            OntModelSpec.OWL_DL_MEM, infModel);
      }
      else
      {
         //invalid inference setting
         System.err.println("Invalid inference setting, "
            + "choose one of <none|rdfs|owl>.");
         return;
      }

      //load the facts into the model
      model.read(inputStream, null, inputFileFormat);

      //validate the file
      ValidityReport validityReport = model.validate();
      if(validityReport != null && !validityReport.isValid())
      {
         Iterator i = validityReport.getReports();
         while(i.hasNext())
         {
            System.err.println(
               ((ValidityReport.Report)i.next()).getDescription());
         }
         return;
      }

      //Iterate over the individuals, print statements about them
      ExtendedIterator iIndividuals = model.listIndividuals();
      while(iIndividuals.hasNext())
      {
         Individual i = (Individual)iIndividuals.next();
         printIndividual(i, writer);
      }
      iIndividuals.close();

      writer.close();
      model.close();
   }

   /**
    * Print information about the individual
    * @param i The individual to output
    * @param writer The writer to which to output
    */
   public static void printIndividual(
      Individual i, PrintWriter writer)
   {
      //print the local name of the individual (to keep it terse)
      writer.println("Individual: " + i.getLocalName());

      //print the statements about this individual
      StmtIterator iProperties = i.listProperties();
      while(iProperties.hasNext())
      {
         Statement s = (Statement)iProperties.next();
         writer.println("  " + s.getPredicate().getLocalName() 
            + " : " + s.getObject().toString());
      }
      iProperties.close();
      writer.println();
   }
}

Answer 1

OWL可以序列化为RDF，而RDF可以序列化为多种不同的格式。 Jena 是一个基于 RDF 的工具，您需要对本体进行 RDF 序列化，以便 Jena 能够读取它。

幸运的是，以

.owl

结尾的文件通常（尽管并非总是）是 OWL 本体 RDF 编码的 RDF/XML 序列化。您还没有向我们展示您的本体，所以我们还不能确定，但最有可能的是，如果您改变

String inputFileFormat = "owl";

到

String inputFileFormat = "RDF/XML";

你会没事的。 （假设您的

.owl

文件是 RDF/XML。）

Answer 2

要解析 OWL/XML 格式的文档（也具有扩展名“.owl”），可以使用 ONT-API。还有 ont-converter - 命令行实用程序。