《重学Java设计模式》之原型模式

原型模式主要解决的问题就是创建重复对象，而这部分对象内容本身比较复杂，生成过程可能从库或者RPC接口中获取数据的耗时较长，因此采用克隆的方式节省时间。

案例：上机考试抽题，要求打乱题目、答案数据

工厂结构

选择题实体类

public class ChoiceQuestion {private String name;                 // 题目private Map<String, String> option;  // 选项；A、B、C、Dprivate String key;                  // 答案；B
}

简答题实体类

public class AnswerQuestion {private String name;  // 问题private String key;   // 答案
}

选项重排工具类

public class TopicRandomUtil {/*** 乱序Map元素，记录对应答案key* @param option 题目* @param key    答案* @return Topic 乱序后 {A=c., B=d., C=a., D=b.}*/static public Topic random(Map<String, String> option, String key) {Set<String> keySet = option.keySet();ArrayList<String> keyList = new ArrayList<String>(keySet);Collections.shuffle(keyList);HashMap<String, String> optionNew = new HashMap<String, String>();int idx = 0;String keyNew = "";for (String next : keySet) {String randomKey = keyList.get(idx++);if (key.equals(next)) {keyNew = randomKey;}optionNew.put(randomKey, option.get(next));}return new Topic(optionNew, keyNew);}
}

克隆对象处理类

public class QuestionBank implements Cloneable{private String candidate; // 考生private String number;    // 考号private ArrayList<ChoiceQuestion> choiceQuestionList = new ArrayList<ChoiceQuestion>();private ArrayList<AnswerQuestion> answerQuestionList = new ArrayList<AnswerQuestion>();public QuestionBank append(ChoiceQuestion choiceQuestion) {choiceQuestionList.add(choiceQuestion);return this;}public QuestionBank append(AnswerQuestion answerQuestion) {answerQuestionList.add(answerQuestion);return this;}@Overridepublic Object clone() throws CloneNotSupportedException {QuestionBank questionBank = (QuestionBank) super.clone();questionBank.choiceQuestionList = (ArrayList<ChoiceQuestion>) choiceQuestionList.clone();questionBank.answerQuestionList = (ArrayList<AnswerQuestion>) answerQuestionList.clone();// 题目乱序Collections.shuffle(questionBank.choiceQuestionList);Collections.shuffle(questionBank.answerQuestionList);// 答案乱序ArrayList<ChoiceQuestion> choiceQuestionList = questionBank.choiceQuestionList;for (ChoiceQuestion question : choiceQuestionList) {Topic random = TopicRandomUtil.random(question.getOption(), question.getKey());question.setOption(random.getOption());question.setKey(random.getKey());}return questionBank;}public void setCandidate(String candidate) {this.candidate = candidate;}public void setNumber(String number) {this.number = number;}@Overridepublic String toString() {StringBuilder detail = new StringBuilder("考生：" + candidate + "\r\n" +"考号：" + number + "\r\n" +"--------------------------------------------\r\n" +"一、选择题" + "\r\n\n");for (int idx = 0; idx < choiceQuestionList.size(); idx++) {detail.append("第").append(idx + 1).append("题：").append(choiceQuestionList.get(idx).getName()).append("\r\n");Map<String, String> option = choiceQuestionList.get(idx).getOption();for (String key : option.keySet()) {detail.append(key).append("：").append(option.get(key)).append("\r\n");;}detail.append("答案：").append(choiceQuestionList.get(idx).getKey()).append("\r\n\n");}detail.append("二、问答题" + "\r\n\n");for (int idx = 0; idx < answerQuestionList.size(); idx++) {detail.append("第").append(idx + 1).append("题：").append(answerQuestionList.get(idx).getName()).append("\r\n");detail.append("答案：").append(answerQuestionList.get(idx).getKey()).append("\r\n\n");}return detail.toString();}}

初始化试题试卷

public class QuestionBankController {private QuestionBank questionBank = new QuestionBank();public QuestionBankController() {Map<String, String> map01 = new HashMap<String, String>();map01.put("A", "JAVA2 EE");map01.put("B", "JAVA2 Card");map01.put("C", "JAVA2 ME");map01.put("D", "JAVA2 HE");map01.put("E", "JAVA2 SE");Map<String, String> map02 = new HashMap<String, String>();map02.put("A", "JAVA程序的main方法必须写在类里面");map02.put("B", "JAVA程序中可以有多个main方法");map02.put("C", "JAVA程序中类名必须与文件名一样");map02.put("D", "JAVA程序的main方法中如果只有一条语句，可以不用{}(大括号)括起来");Map<String, String> map03 = new HashMap<String, String>();map03.put("A", "变量由字母、下划线、数字、$符号随意组成；");map03.put("B", "变量不能以数字作为开头；");map03.put("C", "A和a在java中是同一个变量；");map03.put("D", "不同类型的变量，可以起相同的名字；");Map<String, String> map04 = new HashMap<String, String>();map04.put("A", "STRING");map04.put("B", "x3x;");map04.put("C", "void");map04.put("D", "de$f");Map<String, String> map05 = new HashMap<String, String>();map05.put("A", "31");map05.put("B", "0");map05.put("C", "1");map05.put("D", "2");questionBank.append(new ChoiceQuestion("JAVA所定义的版本中不包括", map01, "D")).append(new ChoiceQuestion("下列说法正确的是", map02, "A")).append(new ChoiceQuestion("变量命名规范说法正确的是", map03, "B")).append(new ChoiceQuestion("以下()不是合法的标识符",map04, "C")).append(new ChoiceQuestion("表达式(11+3*8)/4%3的值是", map05, "D")).append(new AnswerQuestion("小红马和小黑马生的小马几条腿", "4条腿")).append(new AnswerQuestion("铁棒打头疼还是木棒打头疼", "头最疼")).append(new AnswerQuestion("什么床不能睡觉", "牙床")).append(new AnswerQuestion("为什么好马不吃回头草", "后面的草没了"));}public String createPaper(String candidate, String number) throws CloneNotSupportedException {QuestionBank questionBankClone = (QuestionBank) questionBank.clone();questionBankClone.setCandidate(candidate);questionBankClone.setNumber(number);return questionBankClone.toString();}
}

测试

    @GetMapping("/questionBank")public String questionBank() throws CloneNotSupportedException {QuestionBankController questionBankController = new QuestionBankController();System.out.println(questionBankController.createPaper("花花", "1000001921032"));System.out.println(questionBankController.createPaper("豆豆", "1000001921051"));System.out.println(questionBankController.createPaper("大宝", "1000001921987"));return "奖品发放成功!";}