报错类型：找不到Mapper的bean，No qualifying bean of type 'com.aiit.mapper.XXX'

org.springframework.beans.factory.UnsatisfiedDependencyException:
 Error creating bean with name 'com.aiit.MybatisplueApplicationTests': 
Unsatisfied dependency expressed through field 'bookMapper':
 No qualifying bean of type 'com.aiit.mapper.BookMapper' available:
 expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: 
{@org.springframework.beans.factory.annotation.Autowired(required=true)}

他意思就是说你的Mapper没有被注入到容器中，找不到容器中的bean

总共就检查两点：

1.看你的Mapper文件中是否写了注解@Mapper

如何你注解也写了，发现不起作用，那么你尝试一下第二种方法：

2.修改mybatis-plus的依赖版本

 <dependency>

            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.3</version>

 </dependency>

注意：springboot3以上整合Mybatisplus时，mybatisplus版本必须高于3.5.3以上