SpringBoot+MyBatis-Plus项目启动报错：找不到UserMapper Bean依赖

报错信息 #

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'helloController': Unsatisfied dependency expressed through field 'userService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userServiceImpl': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.wms.wms.mapper.UserMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}...
Process finished with exit code 1

问题根源及解决步骤 #

1. 补充MyBatis-Plus核心依赖 #

你的pom.xml仅引入了MyBatis-Plus代码生成器依赖，缺少核心运行依赖，导致Spring无法识别Mapper接口。在<dependencies>节点中添加：

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.1</version> <!-- 与已引入的generator版本保持一致 -->
</dependency>

2. 修正MySQL驱动类 #

MySQL 8.0+版本的驱动类为com.mysql.cj.jdbc.Driver，替换application.yml中的旧驱动类：

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver

3. 修复实体类与数据库字段映射 #

数据库表字段role_id、isValid与实体类roleId、isvalid存在命名规则不匹配，可二选一处理：

• 方式一：开启自动驼峰映射，在application.yml中添加：

  mybatis-plus:
    configuration:
      map-underscore-to-camel-case: true
  

• 方式二：给实体类字段添加注解指定映射关系：

  @TableField("role_id")
  private int roleId;
  @TableField("isValid")
  private String isvalid;
  

4. 确保Mapper接口被Spring扫描（可选但稳妥） #

在启动类WmsApplication上添加@MapperScan注解，明确指定Mapper所在包，避免扫描遗漏：

@SpringBootApplication
@MapperScan("com.wms.wms.mapper")
public class WmsApplication {
    public static void main(String[] args) {
        SpringApplication.run(WmsApplication.class, args);
    }
}

5. 刷新依赖并重启项目 #

执行Maven的clean+compile命令刷新依赖，再重启项目即可。

内容的提问来源于stack exchange，提问作者Cody Qi