我的 java:17.0.5 应用程序基于 struts2-core:6.3.0.2，我使用 log4j-api:2.17.2 作为依赖项，并且应用程序运行良好。 当 log4j-api 提升到 2.20.0（由 struts 支持）时，我遇到了以下异常。我无法理解。
SEVERE [main] org.apache.catalina.core.StandardContext.filterStart Exception starting filter [Struts2Filter]
java.lang.NoClassDefFoundError: Could not initialize class org.apache.logging.log4j.util.PropertiesUtil
at org.apache.logging.log4j.status.StatusLogger.<clinit>(StatusLogger.java:77)
at org.apache.logging.log4j.LogManager.<clinit>(LogManager.java:61)
at org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter.<clinit>(StrutsPrepareAndExecuteFilter.java:49)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:143)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:242)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:97)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4311)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4940)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:683)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:658)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:661)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1014)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1866)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:123)
at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:816)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:468)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1584)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:312)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:114)
at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:402)
at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:345)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:893)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:794)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1332)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1322)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:866)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:248)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:433)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:925)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:171)
at org.apache.catalina.startup.Catalina.start(Catalina.java:735)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:345)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:473)
Caused by: java.lang.ExceptionInInitializerError: Exception java.lang.IllegalArgumentException: key can't be empty [in thread "main"]
at java.base/java.lang.System.checkKey(System.java:1049)
at java.base/java.lang.System.getProperty(System.java:912)
at org.apache.logging.log4j.util.SystemPropertiesPropertySource.getProperty(SystemPropertiesPropertySource.java:96)
at org.apache.logging.log4j.util.SystemPropertiesPropertySource.containsProperty(SystemPropertiesPropertySource.java:104)
at org.apache.logging.log4j.util.PropertiesUtil$Environment.lambda$null$2(PropertiesUtil.java:498)
at java.base/java.lang.Iterable.forEach(Iterable.java:75)
at org.apache.logging.log4j.util.PropertiesUtil$Environment.lambda$reload$3(PropertiesUtil.java:497)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183)
at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
at java.base/java.util.HashMap$KeySpliterator.forEachRemaining(HashMap.java:1707)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596)
at org.apache.logging.log4j.util.PropertiesUtil$Environment.reload(PropertiesUtil.java:494)
at org.apache.logging.log4j.util.PropertiesUtil$Environment.<init>(PropertiesUtil.java:469)
at org.apache.logging.log4j.util.PropertiesUtil$Environment.<init>(PropertiesUtil.java:444)
at org.apache.logging.log4j.util.PropertiesUtil.<init>(PropertiesUtil.java:88)
at org.apache.logging.log4j.util.PropertiesUtil.<init>(PropertiesUtil.java:80)
at org.apache.logging.log4j.util.PropertiesUtil.<clinit>(PropertiesUtil.java:56)
at org.apache.logging.log4j.util.Constants.<clinit>(Constants.java:30)
at org.apache.logging.log4j.spi.AbstractLogger.createClassForProperty(AbstractLogger.java:203)
at org.apache.logging.log4j.spi.AbstractLogger.<clinit>(AbstractLogger.java:92)
... 51 more
我尝试将 log4j-core:2.20.0 添加到类路径中，但这并没有改变任何事情。
根据票证（https://github.com/apache/logging-log4j2/issues/2414）。
异常原因：PropertiesUtil 由于空白键查找而失败。
修复将在 2.24.0 版本中进行