鸿蒙掌上驾考宝典应用开发14：考试引擎设计——ExamManager 与 ExamService 架构

​第14篇考试引擎设计——ExamManager 与 ExamService 架构一、引言考试引擎是整个驾考应用的核心负责试题管理、答题记录、分数统计等核心功能。DriverLicenseExam 项目通过ExamManager和ExamService两个核心类实现了完整的考试引擎。本文将深入解析其架构设计。二、ExamService 数据服务2.1 单例模式ExamService 采用单例模式确保整个应用只有一个数据服务实例// commons/datasource/src/main/ets/ExamService.etsObservedV2exportclassExamService{privatestatic_instance:ExamService;privateexamDetails:ExamDetail[] [];TracemockExamCount:number0;TracemockExamScore:number[] [];staticcontext:Context;constructor() {this.examDetailsthis.generateExamDetail(); }publicstaticinstance(context: Context) {ExamService.context context;if(!ExamService._instance) {ExamService._instancenewExamService(); }returnExamService._instance; } }2.2 核心数据统计方法// 获取总题数publicgetTotalCount(): number {returnthis.examDetails.length; }// 获取已做题数publicgetDidCount(): number {returnthis.examDetails.filter(item item.isCorrect ! undefined).length; }// 获取正确题数publicgetCorrectCount(): number {returnthis.examDetails.filter(item item.isCorrect true).length; }// 获取错题数publicgetErrorCount(): number {returnthis.examDetails.filter(item item.isCorrect false).length; }// 计算正确率publiccalAccuracyRate(): number {constrightCount this.getCorrectCount();consttotalCount this.getTotalCount();if(rightCount 0)return0;returnMath.ceil(rightCount / totalCount *100); }// 计算平均分publiccalculateAverageScore(): number {if(this.mockExamCount 0)return0;returnMath.ceil(this.mockExamScore.reduce((pre, next) pre next) /this.mockExamCount); }三、ExamManager 试卷管理器3.1 试卷数据结构//ExamManager 管理一份试卷 export class ExamManager { name: string | Resource;//试卷名称 examDetails: ExamDetail[];//试题列表 currentQuestionId: number;//当前题目索引 correctNumber: number;//正确数 errorNumber: number;//错误数 timeLimit: number;//限时0表示不限时 }3.2 试卷获取策略// 根据名称和类型获取试卷getManagerByName(name:string|Resource,type:EXAM_MANAGER_TYPE,currentQuestionId:number0,chapterName:string, wrongOrCollect?:WRONG_COLLECT):ExamManager{letexamManager this.examManagerList.find(itemitem.name name);if(examManager undefined|| wrongOrCollect !undefined) {constexamList this.getExamQuestionList(type, chapterName, nameasstring, wrongOrCollect);constcorrectCount this.getCorrectCountByManger(examList);consterrorCount this.getErrorCountByManger(examList); examManager newExamManager(name, examList, currentQuestionId, correctCount, errorCount);// 需要缓存的场景才缓存NEED_NEW_LIST.indexOf(type) -1this.examManagerList.push(examManager); }returnexamManager; }// 模拟考试每次获取新试卷getMockExamManager(name:string| Resource) {letexamManager newExamManager(name,this.generateExamDetail()); examManager.timeLimit1;// 限时1分钟returnexamManager; }四、试题数据模型4.1 ExamDetail 数据结构exportclassExamDetail{ question:string;// 题目文本image?:string;// 题目图片options:string[];// 选项列表correctAnswer:string[];// 正确答案questionType: QuestionTypeEnum;// 题型classificationType: ClassificationTypeEnum;// 难度analysis:string;// 解析chapterName:string;// 章节名称videoUrl:string;// 相关视频isCorrect?:boolean;// 是否答对isCollect:boolean;// 是否收藏selected:string[];// 已选答案}4.2 题型枚举export enum QuestionTypeEnum { RADIO 1,//单选题 CHECK_BOX 2,//多选题 JUDGE 3,//判断题 } export enum ClassificationTypeEnum { EASY 1,//容易 SIMPLE 2,//简单 MIDDLE 3,//一般 EASY_MISTAKE 4,//易错 HARD 5,//困难 }五、总结ExamService ExamManager 构成了完整的考试引擎实现了数据管理试题的增删改查统计计算正确率、平均分等统计指标试卷管理多种试卷类型的获取和缓存数据持久化答题记录和进度的持久化关键源码文件commons/datasource/src/main/ets/ExamService.ets— 考试服务commons/datasource/src/main/ets/Model.ets— 数据模型components/exam/src/main/ets/model/QuestionAnswerRecord.ets— 答题记录​