Jena 本体推理

一，使用Jena对OWL本体进行查询推理

前面在"使用jena持久化OWL本体到MySQL(http://bbs.w3china.org/dispbbs.asp?boardID=2&ID=60494)"中说到了把OWL本体在MySQL中的存取，现在终于能做些简单推理了。要主要规则和查询语句的语法。

 使用sparql对本体进行查询

1）InfModel是对常规Model的扩展，支持任何相关的推理能力

2）QueryExecution 执行sparql查询

3）ResultSetFormatter 获取查询结果集

4）实例中使用了本体文件Experts.owl

二，下面是一个简单的例子：

 public class ReasonerImpl implements IReasoner {

     private InfModel inf = null;

     /**
      * 获取一个推理接口
      * @param path
      * @return
      * @throws RulesetNotFoundException
      */
     private GenericRuleReasoner getReasoner(String path) throws RulesetNotFoundException {

         List<Rule> rules = Rule.rulesFromURL(path);  //"file:./family/family.rules"
         GenericRuleReasoner reasoner = new GenericRuleReasoner(rules);
         reasoner.setOWLTranslation(true);
         reasoner.setDerivationLogging(true);
         reasoner.setTransitiveClosureCaching(true);
         return reasoner;

     }

     /**
      * 获取推理的本体
      * @param path
      * @return
      */
     private OntModel getOntModel(String path) {

         Model model = ModelFactory.createDefaultModel();
         model.read(path);  //"file:./family/family.owl"
         OntModel ont = ModelFactory.createOntologyModel(OntModelSpec.OWL_DL_MEM_RDFS_INF,
                 model);
         Resource configuration = ont.createResource(); //a new anonymous resource linked to this model
         configuration.addProperty(ReasonerVocabulary.PROPruleMode
                 , "hybrid");
         return ont;

     }

     /**
      * InfModel是对常规Model的扩展，支持任何相关的推理能力
      * @param ontPath
      * @param rulePath
      * @return
      */
     public InfModel getInfModel(String rulePath, String ontPath) {

         this.inf = ModelFactory.createInfModel(getReasoner(rulePath), getOntModel(ontPath));
         return this.inf;

     }

     /**
      * InfModel是对常规Model的扩展，支持任何相关的推理能力
      * @param model
      * @param rulePath
      * @return
      */
     public InfModel getInfModel(String rulePath, OntModel model) {
         this.inf = ModelFactory.createInfModel(getReasoner(rulePath), model);
         return this.inf;
     }

     /**
      * 打印推理结果
      * @param a
      * @param b
      */
     public void printInferResult(Resource a, Resource b) {

         StmtIterator stmtIter = this.inf.listStatements(a, null, b);
         if (!stmtIter.hasNext()) {
             System.out.println("there is no relation between "
                       + a.getLocalName() + " and " + b.getLocalName());
             System.out.println("\n-------------------\n");
         }
         while (stmtIter.hasNext()) {
             Statement s = stmtIter.nextStatement();
             System.out.println("Relation between " + a.getLocalName() + " and "
                       + b.getLocalName() + " is :");
             System.out.println(a.getLocalName() + " "
                       + s.getPredicate().getLocalName() + " " + b.getLocalName());
             System.out.println("\n-------------------\n");
         }

     }

     public void searchOnto(String queryString) {

         Query query = QueryFactory.create(queryString);
         QueryExecution qe = QueryExecutionFactory.create(query, this.inf);
         ResultSet results = qe.execSelect();

         ResultSetFormatter.out(System.out, results, query);
         qe.close();

     }

 }

执行查询语句

 public static void testQuery() {
         String ruleFile = "file:./expert/Expert.rules";
         String ontoFile = "file:./expert/Expert.owl";
         String queryString = "PREFIX Expert:<http://www.owl-ontologies.com/Expert.owl#> " +
             "SELECT ?expert ?subject " +
             "WHERE {?expert Expert:familiar_with ?subject} ";

         IReasoner famRea = ReasonerFactory.createFamilyReasoner();
         famRea.getInfModel(ruleFile, ontoFile);
         famRea.searchOnto(queryString);
     }

查询结果为：

 ------------------------------------------------------------
 | expert             | subject                             |
 ============================================================
 | Expert:ChenJianer  | Expert:Computer_Software_and_Theory |
 | Expert:ZhaoHongJie | Expert:Computer_Applied_Technology  |
 ------------------------------------------------------------

源代码下载：http://download.csdn.net/detail/welcome000yy/4770085