问题

启动报错

java.lang.NoClassDefFoundError: io/netty/util/concurrent/DefaultPromise$2    at io.netty.util.concurrent.DefaultPromise.notifyListeners(DefaultPromise.java:589)    at io.netty.util.concurrent.DefaultPromise.setSuccess(DefaultPromise.java:397)    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:155)    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)    at java.lang.Thread.run(Unknown Source)

这个不是真正的谬误，真正的谬误是其余谬误。因为日志不全，所以看不到，解决办法？增加日志文件。具体方法：
https://juejin.im/post/686596...

真正的谬误

INFO: No Spring WebApplicationInitializer types detected on classpathSep 10, 2020 3:00:20 PM org.apache.catalina.core.StandardContext listenerStartSEVERE: Exception sending context initialized event to listener instance of class kalvan.log.logback.web.LogbackConfigListenerjava.lang.ClassCastException: org.slf4j.impl.Log4jLoggerFactory cannot be cast to ch.qos.logback.classic.LoggerContext //转换异样 at kalvan.log.logback.web.LogbackConfigListener.contextInitialized(LogbackConfigListener.java:103) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4994) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5492) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649) at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1081) at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1877) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)Sep 10, 2020 3:00:20 PM org.apache.catalina.core.ApplicationContext logSLF4J: Class path contains multiple SLF4J bindings. //这里才是真正的谬误起因，即同一个类，有多个jar蕴含SLF4J: Found binding in [jar:file:/Users/gongzhihao/IdeaProjects-ys/qrcode/qrcode-server-pool/target/qrcode-server-pool-1.0.0-SNAPSHOT/WEB-INF/lib/activemq-all-5.8.0.jar!/org/slf4j/impl/StaticLoggerBinder.class] //排除这个jarSLF4J: Found binding in [jar:file:/Users/gongzhihao/IdeaProjects-ys/qrcode/qrcode-server-pool/target/qrcode-server-pool-1.0.0-SNAPSHOT/WEB-INF/lib/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class] //只保留这个jarSLF4J: Found binding in [jar:file:/Users/gongzhihao/IdeaProjects-ys/qrcode/qrcode-server-pool/target/qrcode-server-pool-1.0.0-SNAPSHOT/WEB-INF/lib/slf4j-jdk14-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class] //排除这个jarSLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory] //有3个，最终用这个

解决办法：排除其余的，只留下一个。

怎么晓得要排除哪一个jar？

比拟失常的我的项目和异样的我的项目

失常我的项目

异样我的项目 //多了一个jdk14的日志jar，多的jar刚好能够和报错信息匹配

解决办法

排除jar

<exclusions>        <exclusion>          <artifactId>slf4j-jdk14</artifactId>          <groupId>paylib.log</groupId>        </exclusion>        <exclusion>          <artifactId>activemq-all</artifactId>          <groupId>paylib.mq.activemq</groupId>        </exclusion>        <exclusion>          <artifactId>activemq-pool</artifactId>          <groupId>paylib.mq.activemq</groupId>        </exclusion>      </exclusions>