由于springboot默认日志组件为logback，当时项目使用的为log4j，在打war包到tomcat启动时报错：LoggerFactory is not a Logback LoggerContext but Logback is on the classpath.

01-Apr-2020 17:30:37.149 严重 [localhost-startStop-3] org.apache.catalina.core.ContainerBase.addChildInternal ContainerBase.addChild: start: 
    org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/scooper-activiti]]
        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:743)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:719)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:705)
        at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:970)
        at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1841)
        at java.util.concurrent.Executors$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)
    Caused by: java.lang.IllegalArgumentException: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation (class org.apache.logging.slf4j.Log4jLoggerFactory loaded from file:/D:/Program%20Files/Tomcat/webapps/scooper-activiti/WEB-INF/lib/log4j-slf4j-impl-2.12.1.jar). If you are using WebLogic you will need to add 'org.slf4j' to prefer-application-packages in WEB-INF/weblogic.xml: org.apache.logging.slf4j.Log4jLoggerFactory
        at org.springframework.util.Assert.instanceCheckFailed(Assert.java:696)
        at org.springframework.util.Assert.isInstanceOf(Assert.java:596)
        at org.springframework.boot.logging.logback.LogbackLoggingSystem.getLoggerContext(LogbackLoggingSystem.java:281)
        at org.springframework.boot.logging.logback.LogbackLoggingSystem.beforeInitialize(LogbackLoggingSystem.java:104)
        at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationStartingEvent(LoggingApplicationListener.java:239)
        at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:220)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
        at org.springframework.boot.context.event.EventPublishingRunListener.starting(EventPublishingRunListener.java:70)
        at org.springframework.boot.SpringApplicationRunListeners.starting(SpringApplicationRunListeners.java:47)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:305)
        at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.run(SpringBootServletInitializer.java:152)
        at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.createRootApplicationContext(SpringBootServletInitializer.java:132)
        at org.springframework.boot.web.servlet.support.SpringBootServletInitializer.onStartup(SpringBootServletInitializer.java:92)
        at org.springframework.web.SpringServletContainerInitializer.onStartup(SpringServletContainerInitializer.java:172)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5156)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
        ... 10 more

原因：log4j日志组件和自带logback日志组件冲突。
解决方法:
将默认日志组件排除。

        <!-- Spring boot web base. -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>