报错信息如下：

Description:

Field userDao in com.test.springmvc.service.impl.UserServiceImpl required a bean of type 'com.test.springmvc.dao.UserDao' 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 'com.test.springmvc.dao.UserDao' in your configuration.

截图：

项目目录结构：

SpringBootApplication启动类和controller、service、dao包同一级才能扫描到
在保证目录结构没问题的情况下：

1.检查自己的依赖MyBatis相关依赖是否齐全

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.test</groupId>
    <artifactId>springmvc</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springmvc</name>
    <description>SpringMVCPractice</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <!--MyBatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.13</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.6.0</version>
        </dependency>
    </dependencies>

</project>

2.配置文件是否配置了jdbc信息和MyBatis的别名和包扫描

#端口
server.port=8080

#jdbc配置
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/testdb09?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=root

#MyBatis
mybatis.mapper-locations=classpath:com/test/dao/*.xml
mybatis.type-aliases-package=com.test.domain

并检查对应的Mapper文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.test.springmvc.dao.UserDao">

    <select id="findALL" resultType="com.test.springmvc.domain.User">
      select *
      from user
  </select>

    <select id="findById" resultType="com.test.springmvc.domain.User">
        select *
        from user
        where id=#{id}
    </select>

    <insert id="addUser">
        insert into user (name,age)
        values (#{name},#{age})
    </insert>

    <delete id="delUserById">
        delete
        from  user
        where id=#{id}
    </delete>

    <update id="updateUser">
        update user
        set name=#{name},age=#{age}
        where id=#{id}
    </update>

</mapper>

3.最后查看controller、service和dao是否添加了对用的注解。尤其是dao接口上的注解，要加上@Mapper这个ibatis的注解

package com.test.springmvc.dao;

import com.test.springmvc.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
@Mapper
public interface UserDao {

    /**
     * 查询全部User
     *
     * @return
     */
    List<User> findALL();

    /**
     * 根据id查询User
     *
     * @param id
     * @return
     */
    User findById(int id);

    /**
     * 新增User
     *
     * @param user
     * @return
     */
    Integer addUser(User user);

    /**
     * 根据id删除
     *
     * @param id
     * @return
     */
    Integer delUserById(int id);

    /**
     * 修改User
     *
     * @param user
     * @return
     */
    Integer updateUser(User user);

}