SpringBoot一个小案例

pojo

public class User {
    private int userid;
    public User(int userid) {this.userid = userid;}
    public User() {}
    public int getUserid() {return userid;}
    public void setUserid(int userid) {this.userid = userid;}
}

controller

@Controller
@RequestMapping
@ResponseBody
public class FindByIdController {
    @Autowired
    private FindByIdService findByIdService;

    @GetMapping("/practice/{userid}")
    public List<User> findById(@PathVariable int userid) {
        List<User> userids = findByIdService.findById(userid);
        return userids;
    }
}

service

public interface FindByIdService {
    List<User> findById(int userid);
}

serviceImpl

package com.example.demo.service.impl;

import com.example.demo.mapper.FindByIdMapper;
import com.example.demo.pojo.User;
import com.example.demo.service.FindByIdService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;


@Service
public class FindByIdImpl implements FindByIdService {

    @Autowired
    private FindByIdMapper findByIdMapper;

    @Override
    public List<User> findById(int userid) {
        List<Integer> userIds = findByIdMapper.findById(userid);

        List<User> users = new ArrayList<>();

        for (Integer userId : userIds) {
            User user = new User();
            user.setUserid(userId);
            users.add(user);
        }

        return users;
    }
}

mapper

@Mapper
public interface FindByIdMapper {
    @Select("select userid from orguser where departmentid = #{userid}")
    List<Integer> findById(@Param("userid") int userid);
}