com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph 不能轉換為 org.mindswap.pellet.jena.PelletInfGraph

Question

我使用https://www.jarfire.org/pellet.html

運行一個例子，得到錯誤

java.lang.ClassCastException: com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph 無法在 tutorial.HelloWorld.main(HelloWorld.java:178) 中轉換為 org.mindswap.pellet.jena.PelletInfGraph

Model schema = FileManager.get().loadModel("C:/Users/vincent/Downloads/owlDemoSchema.owl");
            Model data = FileManager.get().loadModel("C:/Users/vincent/Downloads/owlDemoData.rdf");
            System.out.println("creating OntModel ");
            OntModel Infmodel = ModelFactory.createOntologyModel(PelletReasonerFactory.THE_SPEC, schema);
                                  //dataset.getNamedModel(this.URL));
            // create an inferencing model using Pellet reasoner
            //InfModel model = ModelFactory.createInfModel(r, schema);
            Reasoner reasoner = ReasonerRegistry.getOWLReasoner();
            InfModel model = ModelFactory.createInfModel(reasoner, data);
            // get the underlying Pellet graph
            PelletInfGraph pellet = (PelletInfGraph) model.getGraph();
            // check for inconsistency
            boolean consistent = pellet.isConsistent();
            if(consistent == true) 
                System.out.println("consistent");
            else
                System.out.println("not consistent");

Answer 1

Reasoner reasoner = ReasonerRegistry.getOWLReasoner();

當您這樣做時，您將獲得來自 Jena 的任何默認 OWL 推理器。 這是一個基於 Jena 基於規則的推理的推理器。 它不是 Pellet 推理機。

這意味着當您創建推理模型時，其推理器是基於規則的推理圖，而不是 Pellet 推理圖，因此此代碼失敗：

InfModel model = ModelFactory.createInfModel(reasoner, data);
// get the underlying Pellet graph
PelletInfGraph pellet = (PelletInfGraph) model.getGraph();

但是，您創建的原始推理模型（包含以下行）背后確實有一個 Pellet 推理器，您可以從中獲得 Pellet 推理圖。

OntModel Infmodel = ModelFactory.createOntologyModel(PelletReasonerFactory.THE_SPEC, schema);

也就是說，你應該使用更像這樣的東西：

OntModel infmodel = ModelFactory.createOntologyModel(PelletReasonerFactory.THE_SPEC);
// load data into the model
PelletInfGraph pellet = (PelletInfGraph) infModel.getGraph();