MabatisPlus注入Mapper接口失败的解决方案

缺乏、安全感 2022-11-08 14:07 166阅读 0赞

Field tCarDao in xxx.xxx.XXX required a bean of type ‘xxx.xxx.XXX’ that could not be found.

The injection point has the following annotations:  
\- @org.springframework.beans.factory.annotation.Autowired(required=true)

##### pom依赖 #####

springboot要下面这个依赖

<dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.3.1.tmp</version>
    </dependency>

--------------------

##### yml配置文件 #####

spring:
      datasource:
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://yumbo.top:3306/sunusedcar?useSSL=false&serverTimezone=GMT%2B8
        username: root
        password: abc123456.
    mybatis-plus:
      configuration:
        map-underscore-to-camel-case: true # 开启驼峰命名

##### mapper接口的定义 #####

需要加上下面两个注解，`@Component`是为了去除注入的下划线，  
`@Mapper`是为了后面注入，启动的时候需要扫描这个`@Mapper`组件

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
    import org.apache.ibatis.annotations.Mapper;
    import org.springframework.stereotype.Component;
    import top.yumbo.entity.User;
    
    @Mapper
    @Component
    public interface UserDao extends BaseMapper<User> { 
    
    }

##### 启动类 #####

需要加上`@MapperScan`扫描UserDao所在的包。

import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.boot.SpringApplication;
    
    @SpringBootApplication
    @MapperScan("top.yumbo.dao")
    public class UserApplication { 
        public static void main(String[] args) { 
            SpringApplication.run(UserApplication.class,args);
        }
    }

其中后面两点缺一不可，也就是解决Mapper注入失败导致springboot无法启动

少了MapperScan会报类似下面的异常，看下面报的异常信息  
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