1. 配置文件的错误

今天在项目启动类中，加上这行代码@MapperScan("com.**.mapper")后，报出了如下错误：

com.superjson.superjsonmanager.SuperJsonManagerApplication
Connected to the target VM, address: '127.0.0.1:49879', transport: 'socket'.   ____          _            __ _ _/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/  ___)| |_)| | | | | || (_| |  ) ) ) )'  |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot ::                (v2.7.1)2022-08-05 16:37:27.699  INFO 152900 --- [           main] c.s.s.SuperJsonManagerApplication        : Starting SuperJsonManagerApplication using Java 1.8.0_102 on DESKTOP-UVTEHFR with PID 152900 (D:\project\1myProject\superjson\superjsonmanager\target\classes started by zby in D:\project\1myProject\superjson\superjsonmanager)
2022-08-05 16:37:27.702  INFO 152900 --- [           main] c.s.s.SuperJsonManagerApplication        : No active profile set, falling back to 1 default profile: "default"
2022-08-05 16:37:28.166  WARN 152900 --- [           main] o.m.s.mapper.ClassPathMapperScanner      : No MyBatis mapper was found in '[com.**.mapper]' package. Please check your configuration.
2022-08-05 16:37:28.408  INFO 152900 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8088 (http)
2022-08-05 16:37:28.414  INFO 152900 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2022-08-05 16:37:28.414  INFO 152900 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.64]
2022-08-05 16:37:28.504  INFO 152900 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2022-08-05 16:37:28.505  INFO 152900 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 772 ms
2022-08-05 16:37:28.719  WARN 152900 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.boot.context.properties.ConfigurationPropertiesBindException: Error creating bean with name 'mybatis-org.mybatis.spring.boot.autoconfigure.MybatisProperties': Could not bind properties to 'MybatisProperties' : prefix=mybatis, ignoreInvalidFields=false, ignoreUnknownFields=true; nested exception is org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under 'mybatis.configuration' to org.apache.ibatis.session.Configuration
2022-08-05 16:37:28.721  INFO 152900 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2022-08-05 16:37:28.729  INFO 152900 --- [           main] ConditionEvaluationReportLoggingListener : Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-08-05 16:37:28.740 ERROR 152900 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : ***************************
APPLICATION FAILED TO START
***************************Description:Failed to bind properties under 'mybatis.configuration' to org.apache.ibatis.session.Configuration:Reason: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [@org.springframework.boot.context.properties.NestedConfigurationProperty org.apache.ibatis.session.Configuration]Action:Update your application's configurationDisconnected from the target VM, address: '127.0.0.1:49879', transport: 'socket'Process finished with exit code 1

通过分析代码后，发现配置文件出现了问题，如下图所示：

字段configuration给到了空值，导致spring boot无法获取到对应的值，报出上面的错误。只要把该字段删除即可启动spring boot。

这个错误存在多种情况，如果以上解决方案无法解决你的问题，可以继续查看如下的解决方案，大概能解决你的实际问题。

2. 编译的错误

仔细看报出的问题，有没有具体报错信息，如上图所示，这种情况进行如下操作：

clean清理一下
然后install重新编译一下

也可以用这个命令，重新编译一下

此时，清除缓存后重新启动，如下图所示：

如果还报同样的错误，打开如下图位置，看是否有编译的文件，如mapper.xml文件，application.yml或者application.properties文件，以及一些配置文件等

这里发现真的没有mapper和配置文件，只有main下面的.jar文件，该怎么办呢？

pom.xml文件中给加入要编译的文件位置依赖，如下：(这是我的文件位置，你根据你的进行调整)

<!--引入本地资源-->
<resources><!--加载lib文件，特殊情况下会有lib，但大部分都靠依赖下载了--><resource><directory>lib</directory><targetPath>BOOT-INF/lib/</targetPath><includes><include>**/*.jar</include></includes></resource><!--打jar包--><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes></resource><!--将properties和xml文件编译--><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>false</filtering></resource>
</resources>

如是，清理 ->打包 -> 启动 -> 运行即可。

3. 定义请求接口重复的错误

日志说明是路径问题，你可以思考下：是不是写的接口名字重复了，或者只有一个斜杠或没斜杠的情况：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'indexController' method
com.superjson.superjsonmanager.controller.IndexController#heart()
to {GET [/heart]}: There is already 'indexController' bean method
com.superjson.superjsonmanager.controller.IndexController#heartbeat() mapped.at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1804) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:955) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.21.jar:5.3.21]at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.21.jar:5.3.21]at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.1.jar:2.7.1]at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734) [spring-boot-2.7.1.jar:2.7.1]at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) [spring-boot-2.7.1.jar:2.7.1]at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) [spring-boot-2.7.1.jar:2.7.1]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) [spring-boot-2.7.1.jar:2.7.1]at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295) [spring-boot-2.7.1.jar:2.7.1]at com.superjson.superjsonmanager.SuperJsonManagerApplication.main(SuperJsonManagerApplication.java:43) [classes/:na]
Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'indexController' method
com.superjson.superjsonmanager.controller.IndexController#heart()
to {GET [/heart]}: There is already 'indexController' bean method
com.superjson.superjsonmanager.controller.IndexController#heartbeat() mapped.at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.validateMethodMapping(AbstractHandlerMethodMapping.java:669) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:635) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:332) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.registerHandlerMethod(RequestMappingHandlerMapping.java:420) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.registerHandlerMethod(RequestMappingHandlerMapping.java:76) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lambda$detectHandlerMethods$2(AbstractHandlerMethodMapping.java:299) ~[spring-webmvc-5.3.21.jar:5.3.21]at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_102]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:297) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.processCandidateBean(AbstractHandlerMethodMapping.java:266) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:225) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:213) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:205) ~[spring-webmvc-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863) ~[spring-beans-5.3.21.jar:5.3.21]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800) ~[spring-beans-5.3.21.jar:5.3.21]... 16 common frames omitted