第一种情况：
整合pom文件时，在未使用通用mapper时启动报错的原因，大多数就是pom文件所使用的版本号不一致，将版本号改为一致即可。
第二种情况：
整合pom文件时，在使用通用mapper时启动报错的原因,错误如下：
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at tk.mybatis.spring.mapper.SpringBootBindUtil$SpringBoot2Bind.bind(SpringBootBindUtil.java:129) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
at tk.mybatis.spring.mapper.SpringBootBindUtil.bind(SpringBootBindUtil.java:58) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
at tk.mybatis.spring.mapper.ClassPathMapperScanner.setMapperProperties(ClassPathMapperScanner.java:48) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
at tk.mybatis.spring.annotation.MapperScannerRegistrar.registerBeanDefinitions(MapperScannerRegistrar.java:33) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.lambda$loadBeanDefinitionsFromRegistrars$1(ConfigurationClassBeanDefinitionReader.java:364) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_191]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsFromRegistrars(ConfigurationClassBeanDefinitionReader.java:363) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:145) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:117) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:327) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:232) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:705) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:531) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) [spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) [spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) [spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) [spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at com.atguigu.gmall.user.GmallUserApplication.main(GmallUserApplication.java:13) [classes/:na]
Caused by: java.lang.reflect.InvocationTargetException: null
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
at tk.mybatis.spring.mapper.SpringBootBindUtil$SpringBoot2Bind.bind(SpringBootBindUtil.java:127) ~[mapper-spring-boot-autoconfigure-1.2.3.jar:na]
... 21 common frames omitted
Caused by: java.util.NoSuchElementException: No value bound
at org.springframework.boot.context.properties.bind.BindResult.get(BindResult.java:56) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
... 26 common frames omitted这种情况下并不是版本的问题了，只需在application.properties 配置文件中加一行mapper.identity=MYSQL就解决了。