ClassNotFoundException 我没有捕获成功

Question

我在java中阅读了很多关于try/catch/finally过程的页面，但我没有成功在我的代码中捕捉到ClassNotFoundException。我使用 for 循环 打开并以 rdfxml 格式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() 并且循环继续处理下一个文件。

问题是我的脚本工作得很好，但是当 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，我收到此消息：

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.run(URLClassLoader.java:372)
    at java.net.URLClassLoader.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，我什么也没收到，代码继续处理下一个文件。我以为我不清楚 try/catch 和 throw 方法是如何工作的。

提前致谢

Answer 1

您只能捕获在 catch(...) 中列出的异常。堆栈跟踪显示 main 方法中的异常是 NoClassDefFoundError。

要解决它，请替换

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

通过（此处捕获所有异常）

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

或通过

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。

查看以下堆栈跟踪片段 - 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 投掷 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 获取 NoClassDefFoundError。从那里你可以得到 getCause 给你包装器 ClassNotFoundException.

ClassNotFoundException 我没有捕获成功

ClassNotFoundException I didn't succeed to catch

java

exception

try-catch-finally