【发布时间】：2014-12-09 16:39:59
【问题描述】：
我有一组从基于 AngularJS 的应用程序异步访问的 JAX-RS 端点。
关于项目...
- Apache CXF JAX-RS，非 Spring Servlet 实现：2.7.7
- 休眠 JPA：4.3.5.Final
- EclipseLink Moxy：2.5.1
- 春季：4.2.1.RELEASE
- 雄猫 7
MOXy 当前是通过注册
org.eclipse.persistence.jaxb.rs.MOXyJsonProvider类到 JAX-RS 应用程序，在 JPA 实体中包含jaxb.properties文件 课程包；文件内容：javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
如果我自己访问端点，一切都会按预期运行。
如果我通过基于 Windows 的本地主机上的浏览器访问 Angular 客户端，一切都会按预期运行。
但是，当我在基于 Linux 的测试环境中测试应用程序时，有时会出现异常，例如：
10:57:38.390 [tomcat-http--27] WARN o.a.c.j.i.WebApplicationExceptionMapper - javax.ws.rs.WebApplicationException: javax.xml.bind.MarshalException
- with linked exception:
[java.lang.NullPointerException]
at org.eclipse.persistence.jaxb.rs.MOXyJsonProvider.writeTo(MOXyJsonProvider.java:842)
at org.apache.cxf.jaxrs.utils.JAXRSUtils.writeMessageBody(JAXRSUtils.java:1317)
at org.apache.cxf.jaxrs.interceptor.JAXRSOutInterceptor.serializeMessage(JAXRSOutInterceptor.java:282)
at org.apache.cxf.jaxrs.interceptor.JAXRSOutInterceptor.processResponse(JAXRSOutInterceptor.java:155)
at org.apache.cxf.jaxrs.interceptor.JAXRSOutInterceptor.handleMessage(JAXRSOutInterceptor.java:86)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:272)
at org.apache.cxf.interceptor.OutgoingChainInterceptor.handleMessage(OutgoingChainInterceptor.java:77)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:272)
at org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)
at org.apache.cxf.transport.http.AbstractHTTPDestination.invoke(AbstractHTTPDestination.java:239)
at org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:248)
at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:222)
at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:153)
at org.apache.cxf.transport.servlet.CXFNonSpringServlet.invoke(CXFNonSpringServlet.java:167)
at org.apache.cxf.transport.servlet.AbstractHTTPServlet.handleRequest(AbstractHTTPServlet.java:286)
at org.apache.cxf.transport.servlet.AbstractHTTPServlet.doGet(AbstractHTTPServlet.java:211)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at org.apache.cxf.transport.servlet.AbstractHTTPServlet.service(AbstractHTTPServlet.java:262)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Caused by: javax.xml.bind.MarshalException
- with linked exception:
[java.lang.NullPointerException]
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:457)
at org.eclipse.persistence.jaxb.rs.MOXyJsonProvider.writeTo(MOXyJsonProvider.java:840)
... 33 more
Caused by: java.lang.NullPointerException
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:145)
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:102)
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:59)
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:401)
at org.eclipse.persistence.internal.oxm.XPathObjectBuilder.buildRow(XPathObjectBuilder.java:240)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:118)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:1)
at org.eclipse.persistence.internal.oxm.XMLCompositeCollectionMappingNodeValue.marshalSingleValue(XMLCompositeCollectionMappingNodeValue.java:328)
at org.eclipse.persistence.internal.oxm.XMLCompositeCollectionMappingNodeValue.marshal(XMLCompositeCollectionMappingNodeValue.java:108)
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:149)
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:102)
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:59)
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:401)
at org.eclipse.persistence.internal.oxm.XPathObjectBuilder.buildRow(XPathObjectBuilder.java:240)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:118)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:1)
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshalSingleValue(XMLCompositeObjectMappingNodeValue.java:249)
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:150)
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:102)
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:59)
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:401)
at org.eclipse.persistence.internal.oxm.XPathObjectBuilder.buildRow(XPathObjectBuilder.java:240)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:118)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:1)
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshalSingleValue(XMLCompositeObjectMappingNodeValue.java:249)
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:150)
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:102)
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:59)
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:401)
at org.eclipse.persistence.internal.oxm.XPathObjectBuilder.buildRow(XPathObjectBuilder.java:240)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:118)
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:1)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:751)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:571)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshalStreamOrWriter(XMLMarshaller.java:1107)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:919)
at org.eclipse.persistence.internal.oxm.XMLMarshaller.marshal(XMLMarshaller.java:862)
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:455)
... 34 more
我能找到的关于我的问题的唯一相关信息是在这个相关的 StackOverflow 问题/答案中：Null pointer exception only on application startup org.eclipse.persistence.jaxb.JAXBMarshaller.marshal
直到我将项目迁移到使用 Spring 进行 Hibernate JPA EntityManager 事务管理之前，这种情况才开始发生。
我完全不知所措。我可以将我的客户端重构为仅发出同步调用，但即便如此，当多个用户尝试同时使用该应用程序时，仍然会出现此问题。为什么 MOXy 会以这种方式行为不端？在多次刷新 Angular 客户端后，这种情况似乎不太常见，因此“启动”系统的概念似乎在某种程度上准确地解释了正在发生的事情。然而，即便如此，这种行为并不一致！似乎没有办法可靠地预测何时会发生这种异常情况。
既然 Spring 正在管理事务，我还需要做些什么，以便在从并发线程快速连续调用时让 MOXy 正确初始化？
总结：
- 访问单个 JAX-RS RESTful 端点时永远不会发生（无论服务器环境如何）
- 永远不会在基于 Windows 的本地主机上发生
- 有时会发生在基于 Linux 的测试服务器上，并且仅在同时访问多个端点时发生
- 有时根本不会发生，即使在这些条件下也是如此
- 仅在从手动/自定义应用程序管理的 Hibernate EntityManager 事务管理迁移到基于 Spring 的事务管理之后才开始发生
【问题讨论】：
-
花了很多 Google-fu 来制作正确的搜索词集，但我发现了这个问题的另一个实例，截至 2.5.1 尚未修复。如果我想要修复，我将不得不使用 MOXy 的 SNAPSHOT 版本。 eclipse.org/forums/index.php/t/667901
-
SNAPSHOT 版本不是必需的。自从我上次检查 MOXy 版本以来，发布了 2.5.2 版。 2.5.2 版（最新的 2.5.x 版本）为我解决了这个问题。我正在添加答案并关闭问题。
标签： spring hibernate jakarta-ee cxf moxy