springboot+mybatis

controller内容如下

UserController

package com.fengzi.controller;
import com.fengzi.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Map;

@Controller
@ResponseBody
public class UserController {

    @Autowired
    private UserService userService;
    @RequestMapping(value = {"/find","/find/{id}"},method = RequestMethod.GET)
    public List<Map<String,Object>> findById(@PathVariable(value = "id", required = false) String id){
        System.out.println(id);
        if (id != null) {
            return userService.findById(id);
        }
        return userService.findAll();
    }
}

dao层内容如下

UserDao

package com.fengzi.dao;

import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Mapper
@Repository
public interface UserDao {
    @Select("select id,name from user where id=#{id}")
    List<Map<String,Object>> findById(@Param(value = "id") String id);

    @Select("select * from user")
    List<Map<String,Object>> findAll();
}

service内容如下

UserService

package com.fengzi.service;
import java.util.List;
import java.util.Map;

public interface UserService {
    List<Map<String,Object>> findById(String id);
    List<Map<String,Object>> findAll();
}

service实现类内容如下

UserServiceImp

package com.fengzi.service.ServiceImp;

import com.fengzi.dao.UserDao;
import com.fengzi.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

@Service
public class UserServiceImp implements UserService {
    @Autowired
    private UserDao userDao;

    public List<Map<String,Object>> findById(String id) {
        return userDao.findById(id);
    }

    public List<Map<String,Object>> findAll() {
        return userDao.findAll();
    }
}

application.yml内容如下

spring:
  datasource:
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://134.175.85.103:3306/testdb
server:
  port: 7001
logging:
  level:
    com.fengzi.dao: debug //可以显示sql语句

最后文件结构如下