在Glassfish4 Java EE应用程序中使用ServiceLoader时出现ClassNo
发布时间：2020-12-15 02:19:18 所属栏目：Java 来源：网络整理
导读：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： ServiceLoaderWorkflowStepSPI loader = ServiceLoader.load(WorkflowStepSPI
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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) 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. （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |