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在Glassfish4 Java EE应用程序中使用ServiceLoader时出现ClassNotFoundException

2019-07-10 21:02:22  阅读：196  来源： 互联网

标签：java java-ee glassfish serviceloader


在Java EE应用程序中,我正在尝试使用Java的ServiceLoader加载服务.我正在尝试加载的.jar文件在测试Java SE应用程序中工作,所以我认为它是正确的.但是,以下代码在itr.next失败：

ServiceLoader<WorkflowStepSPI> loader = ServiceLoader.load(WorkflowStepSPI.class, Thread.currentThread().getContextClassLoader());
        loader.reload();
        List<String> names = new LinkedList<>();
        Iterator<WorkflowStepSPI> itr = loader.iterator();
        while ( itr.hasNext() ) {
            WorkflowStepSPI wss = itr.next();
            logger.log(Level.INFO, "Found WorkflowStepProvider: {0}", wss.getClass().getCanonicalName());
            names.add(wss.toString());
        }

ClassNotFoundException抛出异常,抱怨无法找到WorkflowStepSPI,这显然存在(否则代码无法编译).在另一个测试中,我验证了Class.forName返回此类.

我已经尝试按照建议here创建我自己的URLClassLoader实例,并按照建议here直接加载类,但无济于事.

有任何想法吗？

*更新*

根据要求,这是堆栈跟踪：

Warning:   Class not found: edu/harvard/iq/dataverse/workflow/WorkflowStepSPI
java.lang.NoClassDefFoundError: edu/harvard/iq/dataverse/workflow/WorkflowStepSPI
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:411)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1730)
at org.glassfish.web.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1633)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at java.util.ServiceLoader$LazyIterator.nextService(ServiceLoader.java:370)
at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:404)
at java.util.ServiceLoader$1.next(ServiceLoader.java:480)
at edu.harvard.iq.dataverse.api.WorkflowsAdmin.testSpi(WorkflowsAdmin.java:215)
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:498)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:151)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:171)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:152)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:104)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:387)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:331)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:103)
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:297)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:254)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1028)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:372)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:381)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:344)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:221)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:344)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.ocpsoft.rewrite.servlet.RewriteFilter.doFilter(RewriteFilter.java:205)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at edu.harvard.iq.dataverse.api.ApiBlockingFilter$3.doBlock(ApiBlockingFilter.java:65)
at edu.harvard.iq.dataverse.api.ApiBlockingFilter.doFilter(ApiBlockingFilter.java:157)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at edu.harvard.iq.dataverse.api.ApiRouter.doFilter(ApiRouter.java:30)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:873)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:739)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:575)
at org.apache.catalina.core.ApplicationDispatcher.doDispatch(ApplicationDispatcher.java:546)
at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:428)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:378)
at edu.harvard.iq.dataverse.api.ApiRouter.doFilter(ApiRouter.java:34)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:316)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: edu.harvard.iq.dataverse.workflow.WorkflowStepSPI
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 94 more

解决方法:

通常,当静态编译的类在运行时不可用时会发生NoClassDefError(而不是ClassNotFoundException)(当您尝试通过不存在的反射获取类时发生ClassNotFoundException,例如使用Class.forName()) .

发生的事情是,当您编译代码时,类存在于类路径中.但是,由于各种原因(如果没有看到您的配置无法确定),该类在服务器上不可用.可能的原因是：

>它是您交叉编译项目的另一个项目的一部分(生成.class文件),而其他项目不包含在WAR中(例如,因为它有一个不同的输出目录,其内容未复制到WEB- INF /班)
>它被包含在库中,由于某些原因,它不与WAR一起发货
>您的WAR格式错误且不包含正确的结构(类文件应该放在WEB-INF / classes中,库应该放在WEB-INF / lib中)
>您在不同于编译代码的Java发行版上运行服务器(由于类的包,显然不是这里的情况,但只是想指出它的完整性)

通常,依赖特定于应用程序的WAR与服务器捆绑在一起(在某些服务器特定的文件夹中)是不好的做法.此外,由于应用程序服务器上的某些类加载器分离问题,它会产生细微的错误.相反,您的WAR应包含打包的必需罐子.

标签：java,java-ee,glassfish,serviceloader
来源： https://codeday.me/bug/20190710/1427849.html

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