idea 找到多个名为log4j的片段。这是不合法的相对排序。
13-Aug-2020 16:29:58.965 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.tomcat.util.modeler.BaseModelMBean.invoke 调用方法[manageApp]时发生异常
java.lang.IllegalStateException: 启动子级时出错
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:720)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1727)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:288)
at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:809)
at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:456)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:405)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:288)
at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:809)
at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at java.management/com.sun.jmx.remote.security.MBeanServerAccessController.invoke(MBeanServerAccessController.java:468)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1466)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1307)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1406)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:827)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:359)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:562)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:796)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:677)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:676)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: org.apache.catalina.LifecycleException: 无法启动组件[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/yue_project_war_exploded]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:717)
... 42 more
Caused by: java.lang.IllegalArgumentException: 找到多个名为log4j的片段。这是不合法的相对排序。有关详细信息，请参阅Servlet规范的第8.2.2 2c节。考虑使用绝对排序。
at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2260)
at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2218)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1342)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:983)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:302)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5044)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 43 more
13-Aug-2020 16:29:58.968 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.tomcat.util.modeler.BaseModelMBean.invoke 调用方法[createStandardContext]时发生异常
javax.management.RuntimeOperationsException: 调用方法[manageApp]时发生异常
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:297)
at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:809)
at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:456)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:405)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:288)
at java.management/com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:809)
at java.management/com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at java.management/com.sun.jmx.remote.security.MBeanServerAccessController.invoke(MBeanServerAccessController.java:468)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1466)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1307)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1406)
at java.management.rmi/javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:827)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at java.rmi/sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:359)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:200)
at java.rmi/sun.rmi.transport.Transport$1.run(Transport.java:197)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.Transport.serviceCall(Transport.java:196)
at java.rmi/sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:562)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:796)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:677)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.rmi/sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:676)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.IllegalStateException: 启动子级时出错
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:720)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:690)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1727)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:288)
... 34 more
Caused by: org.apache.catalina.LifecycleException: 无法启动组件[StandardEngine[Catalina].StandardHost[localhost].StandardContext[/yue_project_war_exploded]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:717)
... 42 more
Caused by: java.lang.IllegalArgumentException: 找到多个名为log4j的片段。这是不合法的相对排序。有关详细信息，请参阅Servlet规范的第8.2.2 2c节。考虑使用绝对排序。
at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2260)
at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2218)
at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1342)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:983)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:302)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5044)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 43 more
这个是tomcat启动后的错误日志，先检查了一下pom.xml文件，发现没有问题。于是网上搜索了一下解决办法，看到stack overflow上的这个问答。试了一下子Web.xml文件中添加以下代码
但是，我感觉这个只是掩盖了问题，并不是真的解决了问题。 继续面向搜索引擎编程，然后看到这篇文章。
文章里提到项目里出现了多个同一类型的jar包。于是，我打开项目的target文件夹，然后在\项目名\target\tomcat部署名\WEB-INF\lib下发现出现了不同版本的log4j的jar包以及其他类似情形的jar包。那些jar包看版本号，都应该是我之前pom文件引入过的，但不知道为什么改动pom文件后没有被清理掉
然后，我执行idea 集成的maven 的clean命令，再重新启动tomcat后就好了
原因分析：
我再尝试复现bug的过程中发现。如果pom.xml文件出现过依赖冲突，然后这时候没有修复依赖冲突，而是部署项目并启动tomcat。可能会产生不同版本的jar。然后这个时候，哪怕修改pom.xml，重新导入依赖引用，都不会清除已经产生的额外jar包。
只有maven的clean命令 删除整个target文件夹，再重新编译才可以消除