登录接口
将用户输入的用户名和密码进行验证，查询不为空，存到session中

    /**
     * 登录方法
     */
    @PostMapping("login")
    public String login(User user, HttpSession session){
        User userDB = userService.login(user);
        if(userDB!=null){
            session.setAttribute("user",userDB);
            return "redirect:/file/showAll";
        }else{
            return "redirect:/index";
        }
    }

登录进来用存在session中的值查id展示所有数据

    /**
     * 展示所有文件信息
     */
    @GetMapping("showAll")
    public String findAll(HttpSession session, Model model) {
        //在登录的session中获取用户的id
        User user = (User) session.getAttribute("user");

        //根据用户id查询有的文件信息
        List<UserFile> userFiles = userFileService.findByUserId(user.getId());
        //存入作用域中
        model.addAttribute("files", userFiles);
        return "showAll";
    }

UserService

package com.baizhi.service;

import com.baizhi.entity.User;

public interface UserService {

    User login(User user);
}

UserServciceImpl

package com.baizhi.service;

import com.baizhi.dao.UserDaO;
import com.baizhi.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

@Service
@Transactional
public class UserServciceImpl  implements  UserService{

    @Autowired
    private UserDao userDao;

    @Override
    @Transactional(propagation = Propagation.SUPPORTS)
    public User login(User user) {
        return userDao.login(user);
    }
}

UserDao

package com.baizhi.dao;

import com.baizhi.entity.User;

public interface UserDao {

    User login(User user);
}

UserDaoMapper.xml

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.baizhi.dao.UserDAO">

    <!--login-->
    <select id="login" parameterType="User" resultType="User">
        select id,username,password
        from t_user
        where username=#{username}
        and password = #{password}
    </select>

</mapper>