1）、场景还原

1.创建DAO并且给上注解@Mapper

@Mapper
public interface LoginDao {
    //新增用户方案
    public void addUser(PaymentUser paymentUser);
    //查询用户方案
    public PaymentUser selectUserById(@Param("username") String username);
}

2.yml配置

server:
  port: 80
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    # 当前数据源操作类型
    type: com.alibaba.druid.pool.DruidDataSource
    # mysql驱动类
    url: jdbc:mysql://localhost:3306/pro_ord?useSSL=false&serverTimezone=UTC
    username: root
    password: 123456
mybatis:
  mapper-locations: classpath*:mapper / *.xml
  type-aliases-package: fatcats.top.entities

3.启动报错：

...
***************************
APPLICATION FAILED TO START
***************************

Description:

Field loginMapper in fatcats.top.controller.UserLoginController required a bean of type 'fatcats.top.dao.LoginMapper' 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 'fatcats.top.dao.LoginMapper' in your configuration.


Process finished with exit code 1

4.小编尝试换成在主配置类上使用@MapperScan注解，结果爆红没找到

2）、解决措施

小编查询了很多原因，发现原来是坐标版本在作怪

		 <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
        </dependency>

因为小编在父pom文件导入了mybatis starter

 <!--mybatis-->
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>${mybatis.spring.boot.version}</version>
            </dependency>

所以将上面的坐标版本改成1.3版本一下（父pom没导入starter）
删除即可（父pom导入了）