ClassNotFoundException 我没有成功捕获

Question

我读了很多关于java中try/catch/finally过程的页面，但是我没有成功捕获我代码中的ClassNotFoundException。我使用for循环以rdfxml格式打开并保存我作为参数给出的目录中的每个文件。我想要的是，当我执行代码时，我得到e.getmessage()，循环继续处理下一个文件。

问题是我的脚本工作得很好，但当ClassNotFoundException发生时，我没有收到e.getmessage()

@SuppressWarnings("finally")
public static void main(String[] args) {
    File dir = new File(args[0]);
    File[] directoryListing = dir.listFiles();
    if (directoryListing != null) {
        for (File owlFile : directoryListing){
            String name = owlFile.getName();
                    try {
                        translateOwlToRdfXml(owlFile,name);
                    }
                    catch (OWLOntologyCreationException|OWLOntologyStorageException|ClassNotFoundException e) {
                        System.out.println(name + " has not been saved into RDF/XML;");
                        System.out.println(e.getMessage());
                        }
                    finally {
                        continue;
                    }
                }
            }
        }

    static void translateOwlToRdfXml(File owlFile, String name) throws OWLOntologyCreationException, OWLOntologyStorageException, ClassNotFoundException {
            OWLOntologyManager manager = OWLManager.createOWLOntologyManager();
        System.out.println("Loaded ontology: " + name);
        OWLOntology ontology;
        ontology = manager.loadOntologyFromOntologyDocument(owlFile);
        RDFXMLOntologyFormat rdfxmlFormat = new RDFXMLOntologyFormat();
            manager.saveOntology(ontology, rdfxmlFormat, IRI.create(owlFile));
        System.out.println("Saved ontology in RDF/OWL: " + name);
    }
}

当我不写"finally"块时，我收到这个消息:

Exception in thread "main" java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:58)
Caused by: java.lang.NoClassDefFoundError: com/github/jsonldjava/core/JsonLdError
    at org.openrdf.rio.jsonld.JSONLDParserFactory.getParser(JSONLDParserFactory.java:37)
    at org.openrdf.rio.Rio.createParser(Rio.java:195)
    at org.semanticweb.owlapi.rio.RioParserImpl.parseDocumentSource(RioParserImpl.java:241)
    at org.semanticweb.owlapi.rio.RioParserImpl.parse(RioParserImpl.java:191)
    at uk.ac.manchester.cs.owl.owlapi.ParsableOWLOntologyFactory.loadOWLOntology(ParsableOWLOntologyFactory.java:161)
    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntology(OWLOntologyManagerImpl.java:975)
    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:913)
    at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:928)
    at owl2rdf.owl2rdf.translateOwlToRdfXml(owl2rdf.java:57)
    at owl2rdf.owl2rdf.main(owl2rdf.java:32)
    ... 5 more
Caused by: java.lang.ClassNotFoundException: com.github.jsonldjava.core.JsonLdError
    at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 15 more

但是当我写"finally"时，我什么也没有收到，代码继续处理下一个文件。我想我不太明白try/catch和throw方法是如何工作的。

Thanks in advance

Answer 1

只能捕获在catch(…)中列出的异常。堆栈跟踪显示主方法中的异常是NoClassDefFoundError。

替换

catch (OWLOntologyCreationException|OWLOntologyStorageException|ClassNotFoundException e) {
      System.out.println(name + " has not been saved into RDF/XML;");
      System.out.println(e.getMessage());
}

By(这里捕获所有异常)

catch (Exception e) {
         System.out.println(name + " has not been saved into RDF/XML;");
         System.out.println(e.getMessage());
}

或

catch (OWLOntologyCreationException|OWLOntologyStorageException
|ClassNotFoundException|NoClassDefFoundErrore) {
             System.out.println(name + " has not been saved into RDF/XML;");
             System.out.println(e.getMessage());
}

Answer 2

尝试捕捉NoClassDefFoundError而不是ClassNotFoundException。后者被前者包裹。

请参阅下面的堆栈跟踪片段-这意味着该方法抛出NoClassDefFoundError:

Caused by: java.lang.NoClassDefFoundError: com/github/jsonldjava/core/JsonLdError
at org.openrdf.rio.jsonld.JSONLDParserFactory.getParser(JSONLDParserFactory.java:37)
at org.openrdf.rio.Rio.createParser(Rio.java:195)
at org.semanticweb.owlapi.rio.RioParserImpl.parseDocumentSource(RioParserImpl.java:241)
at org.semanticweb.owlapi.rio.RioParserImpl.parse(RioParserImpl.java:191)
at uk.ac.manchester.cs.owl.owlapi.ParsableOWLOntologyFactory.loadOWLOntology(ParsableOWLOntologyFactory.java:161)
at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntology(OWLOntologyManagerImpl.java:975)
at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:913)
at uk.ac.manchester.cs.owl.owlapi.OWLOntologyManagerImpl.loadOntologyFromOntologyDocument(OWLOntologyManagerImpl.java:928)
at owl2rdf.owl2rdf.translateOwlToRdfXml(owl2rdf.java:57)

Answer 3

translateOwlToRdfXml扔InvocationTargetException。

InvocationTargetException is a checked exception that wraps
an exception thrown by an invoked method or constructor.

您需要捕获此异常，然后使用getTargetException来获取NoClassDefFoundError。从那里你可以得到getCause给你的包装ClassNotFoundException。