错误代码如下：
java.lang.IllegalArgumentException: At least one base package must be specified
at org.springframework.util.Assert.notEmpty(Assert.java:361) \~[spring-core-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:272) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.mybatis.spring.mapper.ClassPathMapperScanner.doScan(ClassPathMapperScanner.java:163) \~[mybatis-spring-1.3.1.jar:1.3.1]
at org.mybatis.spring.annotation.MapperScannerRegistrar.registerBeanDefinitions(MapperScannerRegistrar.java:104) \~[mybatis-spring-1.3.1.jar:1.3.1]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.lambda$loadBeanDefinitionsFromRegistrars$1(ConfigurationClassBeanDefinitionReader.java:358) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) \~[na:1.8.0_161]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsFromRegistrars(ConfigurationClassBeanDefinitionReader.java:357) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:145) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:117) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:328) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:233) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:273) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:93) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:694) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532) \~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) \~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE]
at com.example.demo.DemoApplication.main(DemoApplication.java:13) [classes/:na]
2018-06-13 13:58:11.520 INFO 5960 — [ main] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@78e94dcf: startup date [Wed Jun 13 13:58:11 CST 2018]; root of context hierarchy
Process finished with exit code 1
错误原因：没有在主函数的类中对Mapper层进行扫描
解决：在主函数上加上对mapper层的扫描MapperScan注解
原文链接: https://onlyou.blog.csdn.net//article/details/80678141