Consider defining a bean of type 'com.yxf.demo.dao.IUserMapperDao' in your configuration.

Java报错：

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-07-14 01:11:16.132 ERROR 4216 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

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

Description:

Field userMapper in com.yxf.demo.service.impl.UserServiceImpl required a bean of type 'com.yxf.demo.dao.IUserMapperDao' 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.yxf.demo.dao.IUserMapperDao' in your configuration.


Process finished with exit code 1

原因;注入bean失败。Mybatis的映射配置文件(com.yxf.demo.UserMapper.xml)必须和dao的包结构相同（com.yxf.demo.IUserDao.java）

三种解决方法：

1.调整目录结构

2.加@Mapper注解

import com.yxf.demo.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

@Repository
@Mapper
public interface IUserMapperDao {
    int addUserInfo(User user);
}

3.DemoApplication启动类加@MapperScan(value = "com.yxf.demo.dao")

package com.yxf.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan(value = "com.yxf.demo.dao")
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

}

注意：必要时可两者一起用，等程序运行过一次后，再调试了、看去掉哪个程序可正常运行