基于 AI 辅助的在线考试系统全流程开发实战

设计亮点：AI 生成的 SQL 不仅注释完整，符合企业规范，还针对业务特点做了优化。比如 idx_user_paper 唯一索引有效防止重复考试，cheat_count 字段为防作弊机制预留空间，时间戳字段便于数据追踪。

后端架构：实体、DAO 与 Service 层

实体类设计

基于数据库表结构，AI 自动生成了对应的实体类，采用 Lombok 简化代码：

@Data
@TableName("t_question")
public class Question implements Serializable {
    private static final long serialVersionUID = 1L;

    /** 题目 ID */
    @TableId(type = IdType.AUTO)
    private Long id;

    /** 题目类型 ID */
    @TableField("question_type_id")
    @NotNull(message = "题目类型不能为空")
    private Long questionTypeId;

    /** 科目 ID */
    @TableField("subject_id")
    @NotNull(message = "科目不能为空")
    private Long subjectId;

    /** 题目内容 */
    @TableField("content")
    @NotBlank(message = "题目内容不能为空")
    private String content;

    // ... 其他字段省略
}

这里可以看到 @Data 注解自动生成了 getter/setter，@TableField 处理字段映射，同时集成了 javax.validation 进行参数校验。扩展字段使用 @TableField(exist = false) 定义，避免污染数据库模型。

DAO 层封装

数据访问层采用 MyBatis-Plus，AI 生成的代码不仅包含基础 CRUD，还实现了复杂查询：

public interface QuestionMapper extends BaseMapper<Question> {
    /**
     * 按条件分页查询题目
     * 支持多条件组合查询，包含题目类型、科目、难度、关键词
     */
    @Select("<script>" +
        "SELECT q.*,qt.name as question_type_name,s.name as subject_name " +
        "FROM t_question q " +
        "LEFT JOIN t_question_type qt ON q.question_type_id = qt.id " +
        "LEFT JOIN t_subject s ON q.subject_id = s.id " +
        "<where>" +
        "<if test='questionTypeId != null'>AND q.question_type_id = #{questionTypeId}</if>" +
        "<if test='subjectId != null'>AND q.subject_id = #{subjectId}</if>" +
        "<if test='difficulty != null'>AND q.difficulty = #{difficulty}</if>" +
        "<if test='keyword != null'>AND q.content LIKE CONCAT('%',#{keyword},'%')</if>" +
        "</where>" +
        "ORDER BY q.create_time DESC" +
        "</script>")
    IPage<Question> selectPage(
        @Param("page") Page<Question> page,
        @Param("questionTypeId") Long questionTypeId,
        @Param("subjectId") Long subjectId,
        @Param("difficulty") Integer difficulty,
        @Param("keyword") String keyword);

    /**
     * 随机抽取题目（组卷核心方法）
     */
    @Select("<script>" +
        "SELECT * FROM t_question " +
        "<where>" +
        "subject_id = #{subjectId} " +
        "AND question_type_id = #{questionTypeId} " +
        "AND difficulty = #{difficulty} " +
        "</where> " +
        "ORDER BY RAND() LIMIT #{count}" +
        "</script>")
    List<Question> selectRandomQuestions(
        @Param("subjectId") Long subjectId,
        @Param("questionTypeId") Long questionTypeId,
        @Param("difficulty") Integer difficulty,
        @Param("count") Integer count);
}

动态 SQL 的使用让多条件查询变得灵活，selectRandomQuestions 方法直接支持智能组卷，减少了 N+1 查询问题。

Service 层业务逻辑

Service 层是核心，包含了事务控制和复杂的计分规则：

@Service
@Slf4j
public class ExamServiceImpl implements ExamService {
    @Autowired
    private ExamRecordMapper examRecordMapper;
    @Autowired
    private RedisTemplate<String, Object> redisTemplate;

    /**
     * 开始考试（带事务控制）
     */
    @Override
    @Transactional(rollbackFor = Exception.class)
    public ExamStartVO startExam(Long paperId, Long userId) {
        // 1. 验证试卷状态
        Paper paper = paperMapper.selectById(paperId);
        if (paper == null || paper.getStatus() != 1) {
            throw new BusinessException("试卷未发布或已过期");
        }

        // 2. 检查是否已参加过考试
        QueryWrapper<ExamRecord> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("user_id", userId).eq("paper_id", paperId).in("status", 1, 2);
        ExamRecord existRecord = examRecordMapper.selectOne(queryWrapper);
        if (existRecord != null) {
            throw new BusinessException("您已参加过该考试，不能重复考试");
        }

        // 3. 创建考试记录并缓存至 Redis
        ExamRecord examRecord = new ExamRecord();
        examRecord.setPaperId(paperId);
        examRecord.setUserId(userId);
        examRecord.setStartTime(LocalDateTime.now());
        examRecord.setStatus(1);
        examRecordMapper.insert(examRecord);

        String examKey = "exam:record:" + examRecord.getId();
        redisTemplate.opsForValue().set(examKey, examRecord, paper.getDuration() + 5, TimeUnit.MINUTES);

        return new ExamStartVO(examRecord.getId(), paper.getName(), questions);
    }

    /**
     * 提交答案并自动判分
     */
    @Override
    @Transactional(rollbackFor = Exception.class)
    public ExamResultVO submitAnswer(Long examId, Long userId, List<AnswerDTO> answerList) {
        // 1. 验证考试状态
        ExamRecord examRecord = examRecordMapper.selectById(examId);
        if (examRecord == null || !examRecord.getUserId().equals(userId)) {
            throw new BusinessException("无权操作他人考试记录");
        }

        // 2. 计算得分
        BigDecimal totalScore = BigDecimal.ZERO;
        for (AnswerDTO dto : answerList) {
            Question question = questionMapper.selectById(dto.getQuestionId());
            BigDecimal score = calculateScore(question, dto.getUserAnswer());
            totalScore = totalScore.add(score);
        }

        // 3. 更新记录
        examRecord.setEndTime(LocalDateTime.now());
        examRecord.setStatus(2);
        examRecord.setScore(totalScore);
        examRecordMapper.updateById(examRecord);

        return new ExamResultVO(examId, totalScore, true);
    }

    private BigDecimal calculateScore(Question question, String userAnswer) {
        // 判断题逻辑
        if (question.getQuestionTypeId() == 3) {
            return Objects.equals(userAnswer, question.getAnswer()) 
                ? BigDecimal.valueOf(question.getScore()) : BigDecimal.ZERO;
        }
        // 多选题逻辑（按比例得分）
        if (question.getQuestionTypeId() == 2) {
            String[] correctAnswers = question.getAnswer().split(",");
            String[] userAnswers = userAnswer.split(",");
            int correctCount = 0;
            for (String ans : userAnswers) {
                if (Arrays.asList(correctAnswers).contains(ans)) correctCount++;
                else break; // 错选不得分
            }
            if (correctCount == correctAnswers.length) {
                return BigDecimal.valueOf(question.getScore());
            } else if (correctCount > 0) {
                return BigDecimal.valueOf(question.getScore())
                    .multiply(BigDecimal.valueOf(correctCount))
                    .divide(BigDecimal.valueOf(correctAnswers.length), 1, RoundingMode.HALF_UP);
            }
        }
        return BigDecimal.ZERO;
    }
}

这段代码体现了企业级应用的核心特性：事务一致性保证、Redis 缓存控制考试状态、以及复杂的多选题计分规则。特别是 calculateScore 方法，清晰分离了不同题型的判分逻辑。

Controller 层与 API 设计

控制器层实现了 RESTful 风格的 API 设计，统一响应格式：

@RestController
@RequestMapping("/api/exam")
public class ExamController {
    @PostMapping("/start")
    public Result<ExamStartVO> startExam(@Valid @RequestBody ExamStartDTO dto) {
        try {
            Long userId = SecurityUtils.getCurrentUserId();
            return Result.success(examService.startExam(dto.getPaperId(), userId));
        } catch (BusinessException e) {
            return Result.fail(e.getMessage());
        }
    }

    @PostMapping("/submit")
    public Result<ExamResultVO> submitAnswer(@Valid @RequestBody ExamSubmitDTO dto) {
        try {
            Long userId = SecurityUtils.getCurrentUserId();
            return Result.success(examService.submitAnswer(dto.getExamId(), userId, dto.getAnswerList()));
        } catch (BusinessException e) {
            return Result.fail(e.getMessage());
        }
    }
}

统一的 Result 对象封装了状态码和消息，结合 @Valid 注解实现请求参数校验，异常处理区分业务异常和系统异常，日志分级记录便于排查。

前端交互：Vue 组件与实时功能

前端基于 Vue 和 Element UI，实现了丰富的交互功能：

<template>
  <div class="exam-container">
    <!-- 考试头部信息 -->
    <el-card>
      <h2>{{ paperName }}</h2>
      <p>剩余时间：<span :class="{ warning: remainingTime < 300 }">{{ formatTime(remainingTime) }}</span></p>
      <el-button type="primary" @click="handleSubmit" :loading="submitting">交卷</el-button>
    </el-card>

    <!-- 题目区域 -->
    <el-card>
      <div v-if="currentQuestion">
        <h3>{{ currentQuestionIndex + 1 }}. {{ currentQuestion.content }}</h3>
        <el-radio-group v-if="currentQuestion.questionTypeId === 1" v-model="currentAnswer">
          <el-radio label="A">A. {{ currentQuestion.optionA }}</el-radio>
          <el-radio label="B">B. {{ currentQuestion.optionB }}</el-radio>
        </el-radio-group>
        <el-checkbox-group v-if="currentQuestion.questionTypeId === 2" v-model="currentAnswer">
          <el-checkbox label="A">A. {{ currentQuestion.optionA }}</el-checkbox>
          <el-checkbox label="B">B. {{ currentQuestion.optionB }}</el-checkbox>
        </el-checkbox-group>
      </div>
    </el-card>
  </div>
</template>

<script>
export default {
  data() {
    return {
      remainingTime: 0,
      timer: null,
      cheatWarningCount: 0
    };
  },
  created() {
    this.loadExamData();
    // 监听页面可见性变化（防作弊）
    document.addEventListener('visibilitychange', this.handleVisibilityChange);
  },
  methods: {
    async loadExamData() {
      const res = await this.$api.exam.getExamDetail(this.examId);
      if (res.success) {
        this.questions = res.data.questions;
        this.remainingTime = this.duration * 60;
        this.startTimer();
      }
    },
    startTimer() {
      this.timer = setInterval(() => {
        this.remainingTime--;
        if (this.remainingTime <= 0) this.handleSubmit(true);
      }, 1000);
    },
    handleVisibilityChange() {
      if (document.hidden) {
        this.cheatWarningCount++;
        if (this.cheatWarningCount >= 3) {
          this.$message.warning('检测到多次切换页面，将自动交卷！');
          setTimeout(() => this.handleSubmit(true), 5000);
        }
      }
    }
  }
};
</script>

前端实现了倒计时、自动保存、防作弊监控（页面切换检测）等功能。特别是 handleVisibilityChange 方法，通过监听浏览器焦点变化来记录作弊行为，增强了考试的公平性。

开发效率对比与总结

通过 AI 辅助开发，整体效率提升显著：

质量对比：AI 生成的代码内置了完整的事务管理、异常处理和缓存策略，避免了人工编码时的疏漏。代码遵循统一规范，注释完整，架构清晰。

总结：本次实践展示了 AI 在快速构建企业级应用方面的潜力。它不仅是一个代码生成工具，更是一个全流程的开发助手。对于开发者而言，研究 AI 生成的高质量代码是学习最佳实践的捷径；对于企业，这种模式将大幅降低开发成本，缩短项目周期。未来的软件开发，必将是'人类定义需求，AI 实现细节'的协作模式。