JAXBContext.newInstance()中的NullPointerException

Question

Java开发人员.我正在使用JAXB来创建绑定对象.当我尝试创建JAXBContext这样的:

JAXBContext.newInstance("com.mycompany.jaxb.pkg1:com.mycompany.jaxb.pkg2");

我得到一个NullPointerException:

Exception in thread "main" java.lang.NullPointerException
    at com.sun.xml.bind.v2.model.impl.PropertyInfoImpl.calcXmlName(PropertyInfoImpl.java:287)
    at com.sun.xml.bind.v2.model.impl.PropertyInfoImpl.calcXmlName(PropertyInfoImpl.java:260)
    at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl.getTypes(ElementPropertyInfoImpl.java:100)
    at com.sun.xml.bind.v2.model.impl.RuntimeElementPropertyInfoImpl.getTypes(RuntimeElementPropertyInfoImpl.java:50)
    at com.sun.xml.bind.v2.model.impl.ElementPropertyInfoImpl$1.size(ElementPropertyInfoImpl.java:42)
    at java.util.AbstractList$Itr.hasNext(AbstractList.java:416)
    at com.sun.xml.bind.v2.model.impl.ModelBuilder.getClassInfo(ModelBuilder.java:139)
    at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:49)
    at com.sun.xml.bind.v2.model.impl.RuntimeModelBuilder.getClassInfo(RuntimeModelBuilder.java:41)
    at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:189)
    at com.sun.xml.bind.v2.model.impl.RegistryInfoImpl.<init>(RegistryInfoImpl.java:63)
    at com.sun.xml.bind.v2.model.impl.ModelBuilder.addRegistry(ModelBuilder.java:232)
    at com.sun.xml.bind.v2.model.impl.ModelBuilder.getTypeInfo(ModelBuilder.java:201)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl$3.run(JAXBContextImpl.java:357)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl$3.run(JAXBContextImpl.java:351)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getTypeInfoSet(JAXBContextImpl.java:350)
    at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:216)
    at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:76)
    at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:55)
    at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:124)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:592)
    at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:132)
    at javax.xml.bind.ContextFinder.find(ContextFinder.java:286)
    at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:372)
    at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:337)
    at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:244)
    at com.mycompany.jaxb.JAXBContextFactory.initIfNeeded(JAXBContextFactory.java:66)

谷歌搜索相关的关键字导致我几个讨论线程说这是一个已知的错误,我应该升级到2.0.3版本.但这是我的maven POM文件:

<dependency>
  <groupId>com.sun.xml.bind</groupId>
  <artifactId>jaxb-impl</artifactId>
  <version>2.2.1</version>
</dependency>
<dependency>
  <groupId>javax.xml.bind</groupId>
  <artifactId>jaxb-api</artifactId>
  <version>2.1</version>
</dependency>

......正如你所看到的,我已经超越了2.0.3版.(是的,我尝试回滚到旧版本;它没有帮助.)

有没有人看到这个因为2.0.2或更高版本以外的原因,或者是否有人指出如何追查问题？

Answer 1

好吧，记录一下：我找到了解决方案。

正如多个线程所建议的，此错误的根源是使用早于 2.0.2 的 JAXB 版本。我的错误是我的 maven POM 文件被另一个正在导入旧版本库的 POM 文件覆盖。

感谢斯卡夫曼和其他看过的人。