《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、D
private 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;
}
@Override
public 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;
}
@Override
public 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!";
}
