java.lang.IllegalStateException: Cannot load driver class: com.mysql.jdbc.Driver

问题：

Caused by: java.lang.IllegalStateException: Cannot load driver class: com.mysql.jdbc.Driver
	at org.springframework.util.Assert.state(Assert.java:94) ~[spring-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.determineDriverClassName(DataSourceProperties.java:224) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.initializeDataSourceBuilder(DataSourceProperties.java:176) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration.createDataSource(DataSourceConfiguration.java:44) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari.dataSource(DataSourceConfiguration.java:88) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari$$EnhancerBySpringCGLIB$$82c91fcd.CGLIB$dataSource$0(<generated>) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari$$EnhancerBySpringCGLIB$$82c91fcd$$FastClassBySpringCGLIB$$1af385d7.invoke(<generated>) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari$$EnhancerBySpringCGLIB$$82c91fcd.dataSource(<generated>) ~[spring-boot-autoconfigure-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	... 69 common frames omitted

原因：mysql驱动未加载，pom文件忘记添加mysql驱动包的坐标

解决方案：添加mysql驱动包的坐标

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <scope>runtime</scope>
</dependency>

启动项目，OK。