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开始尝试从0写一个项目--后端（二）

news 2025/6/23 16:57:15

实现学生管理

新增学生

接口设计

请求路径：/admin/student

请求方法：POST

请求参数：请求头：Headers："Content-Type": "application/json"

请求体：Body：

id 学生id

idNumber 学生身份证

name 名字

phone 电话号码

sex 性别

username 用户名

返回数据：Result

student表设计

字段名	数据类型	说明	备注
id	bigint	主键	自增
name	varchar(32)	姓名
username	varchar(32)	用户名	唯一
password	varchar(64)	密码
phone	varchar(11)	手机号
sex	varchar(2)	性别
id_number	varchar(18)	身份证号
status	Int	账号状态	1正常 0锁定
create_time	Datetime	创建时间
update_time	datetime	最后修改时间
create_user	bigint	创建人id
update_user	bigint	最后修改人id

代码开发

设计DTO类接收前端传来的参数

sems-pojo/src/main/java/com/ljc/dto/StudentDTO.java

package com.ljc.dto;import lombok.Data;import java.io.Serializable;@Data
public class StudentDTO implements Serializable {//学生idprivate Long id;//用户名private String username;//姓名private String name;//电话private String phone;//性别private String sex;//身份证号private String idNumber;}

controller层

sems-server/src/main/java/com/ljc/controller/student/StudentController.java

package com.ljc.controller.student;import com.ljc.constant.JwtClaimsConstant;
import com.ljc.dto.StudentDTO;
import com.ljc.dto.StudentLoginDTO;
import com.ljc.entity.Student;
import com.ljc.properties.JwtProperties;
import com.ljc.result.Result;
import com.ljc.service.StudentService;
import com.ljc.utils.JwtUtil;
import com.ljc.vo.StudentLoginVO;import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.HashMap;
import java.util.Map;@RestController
@RequestMapping("/admin/student")
@Slf4j
public class StudentController {@Autowiredprivate StudentService studentService;@Autowiredprivate JwtProperties jwtProperties;/*** 登录** @param studentLoginDTO* @return*/@ApiOperation("用户登录")@PostMapping("/login")public Result<StudentLoginVO> login(@RequestBody StudentLoginDTO studentLoginDTO) {log.info("学生登录：{}", studentLoginDTO);Student student = studentService.login(studentLoginDTO);//登录成功后，生成jwt令牌Map<String, Object> claims = new HashMap<>();claims.put(JwtClaimsConstant.EMP_ID, student.getId());String token = JwtUtil.createJWT(jwtProperties.getAdminSecretKey(),jwtProperties.getAdminTtl(),claims);StudentLoginVO studentLoginVO = StudentLoginVO.builder().id(student.getId()).userName(student.getUsername()).name(student.getName()).token(token).build();return Result.success(studentLoginVO);}/*** 退出** @return*/@ApiOperation("用户退出")@PostMapping("/logout")public Result<String> logout() {return Result.success();}/*** 新增学生* @param studentDTO* @return*/@PostMapping@ApiOperation("新增学生")public Result save(@RequestBody StudentDTO studentDTO){//日志，现在进行的是新增学生功能log.info("新增学生：{}", studentDTO);//调用service层（处理层）的方法进行新增studentService.save(studentDTO);return Result.success();}}

Service层

sems-server/src/main/java/com/ljc/service/StudentService.java

package com.ljc.service;import com.ljc.dto.StudentDTO;
import com.ljc.dto.StudentLoginDTO;
import com.ljc.entity.Student;public interface StudentService {/*** 学生登录* @param studentLoginDTO* @return*/Student login(StudentLoginDTO studentLoginDTO);/*** 新增学生* @param studentDTO*/void save(StudentDTO studentDTO);
}

ServiceImpl层

sems-server/src/main/java/com/ljc/service/impl/StudentServiceImpl.java

package com.ljc.service.impl;import com.ljc.constant.MessageConstant;
import com.ljc.constant.PasswordConstant;
import com.ljc.constant.StatusConstant;
import com.ljc.context.BaseContext;
import com.ljc.dto.StudentDTO;
import com.ljc.dto.StudentLoginDTO;
import com.ljc.entity.Student;
import com.ljc.exception.AccountLockedException;
import com.ljc.exception.AccountNotFoundException;
import com.ljc.exception.PasswordErrorException;
import com.ljc.mapper.StudentMapper;
import com.ljc.service.StudentService;import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.DigestUtils;import java.time.LocalDateTime;@Service
public class StudentServiceImpl implements StudentService {@Autowiredprivate StudentMapper studentMapper;/*** 学生登录** @param studentLoginDTO* @return*/public Student login(StudentLoginDTO studentLoginDTO) {String username = studentLoginDTO.getUsername();String password = studentLoginDTO.getPassword();//1、根据用户名查询数据库中的数据Student student = studentMapper.getByUsername(username);//2、处理各种异常情况（用户名不存在、密码不对、账号被锁定）if (student == null) {//账号不存在throw new AccountNotFoundException(MessageConstant.ACCOUNT_NOT_FOUND);}//密码比对// 进行md5加密，然后再进行比对password = DigestUtils.md5DigestAsHex(password.getBytes());if (!password.equals(student.getPassword())) {//密码错误throw new PasswordErrorException(MessageConstant.PASSWORD_ERROR);}if (student.getStatus() == StatusConstant.DISABLE) {//账号被锁定throw new AccountLockedException(MessageConstant.ACCOUNT_LOCKED);}//3、返回实体对象return student;}/**** 新增学生* @param studentDTO*/@Overridepublic void save(StudentDTO studentDTO) {//1. 创建一个学生对象Student student = new Student();//2. 将前端传后来的参数，即就是封装在DTO里面的数据转移到学生对象中//调用对象属性拷贝，括号里面参数，前面的是需要传递的数据，后面的是接收的数据BeanUtils.copyProperties(studentDTO,student);//3. 补充student里面的数据，前端没有传递回来的//3.1 前端没有传递账号状态，现在给设置账号状态:默认为正常，正常为1，异常为0；//由于1太不美观了，创建一个常量类/*student.setStatus(1);*/student.setStatus(StatusConstant.ENABLE);//3.2 设置密码:默认为123456，进行MD5加密//密码也设置一个常量：PasswordConstant.DEFAULT_PASSWORD/*student.setPassword(DigestUtils.md5DigestAsHex("123456".getBytes()));*/student.setPassword(DigestUtils.md5DigestAsHex(PasswordConstant.DEFAULT_PASSWORD.getBytes()));//3.3 设置创建时间和修改时间: 为当前时间student.setCreateTime(LocalDateTime.now());student.setUpdateTime(LocalDateTime.now());//3.4 设置创建人的idstudent.setCreateUser(BaseContext.getCurrentId());student.setUpdateUser(BaseContext.getCurrentId());//4 调用mapper层数据，连接数据库，对数据库进行操作studentMapper.insert(student);}}

mapper层

sems-server/src/main/java/com/ljc/mapper/StudentMapper.java

package com.ljc.mapper;import com.ljc.entity.Student;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;@Mapper
public interface StudentMapper {/*** 根据用户名查询学生* @param username* @return*/@Select("select * from student where username = #{username}")Student getByUsername(String username);/*** 新增学生* @param student*/@Insert("insert into student (name, username, password, phone, sex, id_number, create_time, update_time, create_user, update_user,status) " +"values " +"(#{name},#{username},#{password},#{phone},#{sex},#{idNumber},#{createTime},#{updateTime},#{createUser},#{updateUser},#{status})")void insert(Student student);
}

补充代码

这里面有几个常量值，和一个ThreadLocal来获取jwt令牌里面的用户名

封装了 ThreadLocal 操作的工具类：

sems-common/src/main/java/com/ljc/context/BaseContext.java

package com.ljc.context;public class BaseContext {public static ThreadLocal<Long> threadLocal = new ThreadLocal<>();public static void setCurrentId(Long id) {threadLocal.set(id);}public static Long getCurrentId() {return threadLocal.get();}public static void removeCurrentId() {threadLocal.remove();}}

常量类

密码

sems-common/src/main/java/com/ljc/constant/PasswordConstant.java

package com.ljc.constant;/*** 密码常量*/
public class PasswordConstant {public static final String DEFAULT_PASSWORD = "123456";}

补充用户名重复常量

sems-common/src/main/java/com/ljc/constant/MessageConstant.java

package com.ljc.constant;/*** 信息提示常量类*/
public class MessageConstant {public static final String PASSWORD_ERROR = "密码错误";public static final String ACCOUNT_NOT_FOUND = "账号不存在";public static final String ACCOUNT_LOCKED = "账号被锁定";public static final String UNKNOWN_ERROR = "未知错误";public static final String USER_NOT_LOGIN = "用户未登录";public static final String CATEGORY_BE_RELATED_BY_SETMEAL = "当前分类关联了套餐,不能删除";public static final String CATEGORY_BE_RELATED_BY_DISH = "当前分类关联了菜品,不能删除";public static final String SHOPPING_CART_IS_NULL = "购物车数据为空，不能下单";public static final String ADDRESS_BOOK_IS_NULL = "用户地址为空，不能下单";public static final String LOGIN_FAILED = "登录失败";public static final String UPLOAD_FAILED = "文件上传失败";public static final String SETMEAL_ENABLE_FAILED = "套餐内包含未启售菜品，无法启售";public static final String PASSWORD_EDIT_FAILED = "密码修改失败";public static final String DISH_ON_SALE = "起售中的菜品不能删除";public static final String SETMEAL_ON_SALE = "起售中的套餐不能删除";public static final String DISH_BE_RELATED_BY_SETMEAL = "当前菜品关联了套餐,不能删除";public static final String ORDER_STATUS_ERROR = "订单状态错误";public static final String ORDER_NOT_FOUND = "订单不存在";public static final String ALREADY_EXISTS = "已存在";
}

处理用户名重复的异常

sems-server/src/main/java/com/ljc/handler/GlobalExceptionHandler.java

package com.ljc.handler;import com.ljc.constant.MessageConstant;
import com.ljc.exception.BaseException;
import com.ljc.result.Result;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;import java.sql.SQLIntegrityConstraintViolationException;/*** 全局异常处理器，处理项目中抛出的业务异常*/
@RestControllerAdvice
@Slf4j
public class GlobalExceptionHandler {/*** 捕获业务异常* @param ex* @return*/@ExceptionHandlerpublic Result exceptionHandler(BaseException ex){log.error("异常信息：{}", ex.getMessage());return Result.error(ex.getMessage());}/*** 捕获用户名重复* */@ExceptionHandlerpublic Result exceptionHandler(SQLIntegrityConstraintViolationException ex){//Duplicate entry 'zhangsan' for key 'employee.idx_username'//获取异常信息String massage = ex.getMessage();//以” “分割异常信息；if (massage.contains("Duplicate entry")){String[] split = massage.split(" ");String name = split[2];String msg = name+ MessageConstant.ALREADY_EXISTS;//已存在已有常量，尽量避免字符串return Result.error(msg);}else {return Result.error(MessageConstant.UNKNOWN_ERROR);}}}