Jena学习笔记(3)——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