SpringBoot启动服务器失败，详细的报错日志如下：
java.lang.IllegalStateException: Failed to introspect Class [org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration] from ClassLoader [sun.misc.Launcher$AppClassLoader@4e0e2f2a] at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:481) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:358) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.util.ReflectionUtils.getUniqueDeclaredMethods(ReflectionUtils.java:414) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.lambda$getTypeForFactoryMethod$2(AbstractAutowireCapableBeanFactory.java:743) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(Unknown Source) ~[na:1.8.0_66] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod(AbstractAutowireCapableBeanFactory.java:742) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:681) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:649) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1605) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:523) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:494) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:99) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE] at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:140) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE] at com.test.TestMain.main(TestMain.java:31) [main/:na] Caused by: java.lang.NoClassDefFoundError: org/springframework/transaction/ReactiveTransactionManager at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_66] at java.lang.Class.privateGetDeclaredMethods(Unknown Source) ~[na:1.8.0_66] at java.lang.Class.getDeclaredMethods(Unknown Source) ~[na:1.8.0_66] at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:463) ~[spring-core-5.2.5.RELEASE.jar:5.2.5.RELEASE] ... 19 common frames omitted Caused by: java.lang.ClassNotFoundException: org.springframework.transaction.ReactiveTransactionManager at java.net.URLClassLoader.findClass(Unknown Source) ~[na:1.8.0_66] at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.8.0_66] at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) ~[na:1.8.0_66] at java.lang.ClassLoader.loadClass(Unknown Source) ~[na:1.8.0_66] ... 23 common frames omitted
报错时使用的 spring-boot-starter版本2.2.6.RELEASE，mybatis-spring-boot-starter版本1.3.2。
之前 spring-boot-starter使用版本2.0.1.RELEASE时，不会出现这个异常。 尝试将 mybatis-spring-boot-starter 版本升级到 2.1.2，问题解决。
补充：
mybatis-spring-boot-starter 版本升级到 2.1.2后，服务器能够正常运行，但是启动时会打印警告日志：
Loading class `com.mysql.jdbc.Driver‘. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver‘. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
改成
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
问题解决。