spring boot包扫描不到controller层

启动类代码

package com.maven.demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@SpringBootApplication
@EnableAutoConfiguration
@ComponentScan("com.maven.demo")
@MapperScan("com.maven.demo")
@EnableTransactionManagement
public class DemoApplication {

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

发现路径都是对的，但是就是扫描不到controller层

原因是maven多模块项目忘记引入子模块的maven依赖了，启动类是一个子模块，controller的代码是另外一个子模块，低级错误。