某日新创建spring boot项目后启动项目报错：
Description:
Field studentsMapper in site.longkui.app.service.StudentsService required a bean of type 'site.longkui.app.mapper.StudentsMapper' that could not be found.
The injection point has the following annotations:
- @org.springframework.beans.factory.annotation.Autowired(required=true)
Action:
Consider defining a bean of type 'site.longkui.app.mapper.StudentsMapper' in your configuration.
这个错误是因为我们没有加上MapperScan注解。
我们找到启动类，在前面加上@MapperScan注解，并加入需要扫描是包路径。比如下面这样：
@SpringBootApplication
@MapperScan("site.longkui.**.mapper")
public class AppApplication {
public static void main(String[] args) {
SpringApplication.run(AppApplication.class, args);
}
}其中，**表示模糊匹配，方便后期项目进行扩展。然后重新启动项目就正常了。