【发布时间】：2014-04-03 18:32:44
【问题描述】：
我尝试使用以下 java 代码来获取本体并返回狮子类的实例，但是当我尝试运行该文件时，我在第 16 行遇到错误。所以我正在等待请帮忙！
import com.hp.hpl.jena.rdf.model.*;
import com.hp.hpl.jena.util.FileManager;
import com.hp.hpl.jena.vocabulary.RDF;
import com.hp.hpl.jena.sparql.util.IndentedWriter;
import com.hp.hpl.jena.query.*;
public class Jungle1
{
public static final String jungle_file = "jungle.n3";
public static final String NL = System.getProperty("line.separator") ;
public static void main( String[] args ) {
// create the simplest model there is
//
Model m = ModelFactory.createDefaultModel();
// use the file manager to read an RDF document into the model
FileManager.get().readModel( m, jungle_file );
log.debug( "We have loaded a model with no. statements = " + m.size() );
String jungle ="http://www.lirmm.fr/jungle#";
String prolog1 = "PREFIX jungle: <"+jungle+">" ;
String prolog2 = "PREFIX rdf: <"+RDF.getURI()+">" ;
// Query string.
String queryString = prolog1 + NL + prolog2 + NL +
"SELECT ?individu WHERE {?individu rdf:type jungle:Lion }" ;
Query query = QueryFactory.create(queryString) ;
// Print with line numbers
query.serialize(new IndentedWriter(System.out,true)) ;
System.out.println() ;
// Create a single execution of this query, apply to a model
// which is wrapped up as a Dataset
QueryExecution qexec = QueryExecutionFactory.create(query, m) ;
// Or QueryExecutionFactory.create(queryString, model) ;
System.out.println("Les Lions : ") ;
try {
// Assumption: it’s a SELECT query.
ResultSet rs = qexec.execSelect() ;
// The order of results is undefined.
for ( ; rs.hasNext() ; )
{
QuerySolution rb = rs.nextSolution() ;
// Get title - variable names do not include the ’?’
RDFNode y = rb.get("individu");
System.out.print("uri : "+y+"--- ");
Resource z = (Resource) rb.getResource("individu");
System.out.println("plus simplement "+z.getLocalName());
}
}
finally
{
// QueryExecution objects should be closed to free any system resources
qexec.close() ;
}
}
}
这是 N3 文件：
# Base: http://www.lirmm.fr/jungle#
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix default: <http://www.lirmm.fr/jungle#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
default:Carnivore
a owl:Class ;
rdfs:subClassOf default:Animal ;
owl:equivalentClass
[ a owl:Restriction ;
owl:allValuesFrom default:Animal ;
owl:onProperty default:eats
] .
default:Lea
a default:Carnivore ;
default:hasScientificName
"Panthera leo"^^xsd:string .
default:Animal
a owl:Class ;
rdfs:subClassOf owl:Thing ;
rdfs:subClassOf
[ a owl:Restriction ;
owl:cardinality "1"^^xsd:int ;
owl:onProperty default:hasScientificName
] .
default:Lion
a owl:Class ;
rdfs:subClassOf default:Carnivore ;
owl:equivalentClass
[ a owl:Restriction ;
owl:hasValue "Panthera leo"^^xsd:string ;
owl:onProperty default:hasScientificName
] .
default:eats
a owl:ObjectProperty ;
rdfs:domain default:Animal ;
owl:inverseOf default:eaten_by .
default:Cleo
a default:Lion .
default:Leo
a default:Lion .
<http://www.lirmm.fr/jungle>
a owl:Ontology .
default:Clea
a default:Animal ;
default:hasScientificName
"Panthera leo"^^xsd:string .
default:eaten_by
a owl:ObjectProperty ;
rdfs:range default:Animal ;
owl:inverseOf default:eats .
default:Herbivore
a owl:Class ;
rdfs:subClassOf default:Animal .
default:gigi
a default:Giraffe ;
default:hasScientificName
"Giraffa camelopardalis"^^xsd:string .
default:Plant
a owl:Class .
default:hasScientificName
a owl:DatatypeProperty ;
rdfs:range xsd:string .
default:Giraffe
a owl:Class ;
rdfs:subClassOf default:Herbivore .
错误如下：
log4j:WARN No appenders could be found for logger (org.apache.jena.riot.stream.JenaIOEnvironment).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Exception in thread "main" org.apache.jena.riot.RiotNotFoundException: Not found: jungle.n3
at org.apache.jena.riot.RDFDataMgr.open(RDFDataMgr.java:831)
at org.apache.jena.riot.RDFDataMgr.open(RDFDataMgr.java:813)
at org.apache.jena.riot.RDFDataMgr.parse(RDFDataMgr.java:684)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:208)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:141)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:130)
at org.apache.jena.riot.adapters.AdapterFileManager.readModelWorker(AdapterFileManager.java:291)
at com.hp.hpl.jena.util.FileManager.readModel(FileManager.java:369)
at com.hp.hpl.jena.util.FileManager.readModel(FileManager.java:353)
at Jungle1.main(Jungle1.java:28)
【问题讨论】：
-
究竟是什么错误？你能提供一个堆栈跟踪吗？
-
错误如下：线程“main”中的异常java.lang.Error：未解决的编译问题：无法解析日志IndentedWriter无法解析为Jungle1.main的类型（Jungle1.java： 16)
-
什么是堆栈跟踪？我是java新手
-
您会在运行时获得未捕获异常的堆栈跟踪。在你的情况下，你的代码甚至没有编译，所以你没有堆栈跟踪。