分层解耦

三层架构
1）Controller：控制层。接收前端发送的请求，对请求进行处理，并响应数据。
2）Service：业务逻辑层。处理具体的业务逻辑。
3）Dao：数据访问层(Data Access Object)，也称为持久层。负责数据访问操作，包括数据的增、删、改、查。
UserController类

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package com.itheima.controller;import cn.hutool.core.io.IoUtil;
import com.itheima.pojo.User;
//import com.itheima.service.UserService;
//import com.itheima.service.impl.UserServiceImpl;
import com.itheima.service.UserService;
import com.itheima.service.impl.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.List;@RestController
public class UserController {
@Autowiredprivate UserService userService ;@RequestMapping("/list")public List<User> list(){//1.调用ServiceList<User> userList = userService.findAll();//2.响应数据return userList;}//    @RequestMapping("/list")
//    public List<User> list() throws Exception{
//        //1.加载并读取文件
//        InputStream in = this.getClass().getClassLoader().getResourceAsStream("user.txt");
//        ArrayList<String> lines = IoUtil.readLines(in, StandardCharsets.UTF_8, new ArrayList<>());
//
//        //2.解析数据，封装成对象 --> 集合
//        List<User> userList = lines.stream().map(line -> {
//            String[] parts = line.split(",");
//            Integer id = Integer.parseInt(parts[0]);
//            String username = parts[1];
//            String password = parts[2];
//            String name = parts[3];
//            Integer age = Integer.parseInt(parts[4]);
//            LocalDateTime updateTime = LocalDateTime.parse(parts[5], DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
//
//            return new User(id, username, password, name, age, updateTime);
//        }).toList();
//
//        //3.响应数据
//        //return JSONUtil.toJsonStr(userList, JSONConfig.create().setDateFormat("yyyy-MM-dd HH:mm:ss"));
//        return userList;
//    }}

UserSerivce接口

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package com.itheima.service;import com.itheima.pojo.User;
import java.util.List;public interface UserService {public List<User> findAll();}

UserSerivceImpl

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package com.itheima.service.impl;import com.itheima.dao.UserDao;
import com.itheima.dao.impl.UserDaoImpl;
import com.itheima.pojo.User;
import com.itheima.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.List;
import java.util.stream.Collectors;
@Service
public class UserServiceImpl implements UserService {
@Autowiredprivate UserDao userDao ;@Overridepublic List<User> findAll() {List<String> lines = userDao.findAll();List<User> userList = lines.stream().map(line -> {String[] parts = line.split(",");Integer id = Integer.parseInt(parts[0]);String username = parts[1];String password = parts[2];String name = parts[3];Integer age = Integer.parseInt(parts[4]);LocalDateTime updateTime = LocalDateTime.parse(parts[5], DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));return new User(id, username, password, name, age, updateTime);}).collect(Collectors.toList());return userList;}
}

UserDao接口

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package com.itheima.dao;import java.util.List;public interface UserDao {public List<String> findAll();}

UserDaoImpl

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package com.itheima.dao.impl;import cn.hutool.core.io.IoUtil;
import com.itheima.dao.UserDao;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
@Repository
public class UserDaoImpl implements UserDao {@Overridepublic List<String> findAll() {InputStream in = this.getClass().getClassLoader().getResourceAsStream("user.txt");ArrayList<String> lines = IoUtil.readLines(in, StandardCharsets.UTF_8, new ArrayList<>());return lines;}
}