JSON转换的实现

String转成JSON
这个依赖很重要，我们将围绕fastjson中的JSONObject这个类来谈转换 

1 <dependency>
2 <groupId>com.alibaba</groupId>
3 <artifactId>fastjson</artifactId>
4 <version>1.2.15</version>
5 </dependency>

String转成JSON

1 String json = "{"abc":"1","hahah":"2"}";
2 JSONObject jsonObject = JSONObject.parseObject(content);

一句话就能解决，非常便捷。
想要取出值，可以对`jsonObject`进行操作：
jsonObject.getString("abc");
结果为：`1`

将String转为list后转为JSON

1 List<String> list = new ArrayList<String>(); 
2 list.add("username"); 
3 list.add("age"); 
4 list.add("sex"); 
5 JSONArray array = new JSONArray(); 
6 array.add(list);

将String转为map后转为JSON

1 Map<String, String> map = new HashMap<String, String>();
2 map.put("abc", "abc");
3 map.put("def", "efg");
4 JSONArray array_test = new JSONArray();
5 array_test.add(map);
6 JSONObject jsonObject = JSONObject.fromObject(map);

特别注意:从JSONObject中取值，碰到了数字为key的时候，如

{
"userAnswer": {
"28568": {
"28552": {
"qId": "28552",
"order": "1",
"userScore": {
"score": 100
},
"answer": {
"28554": "28554"
},
"qScore": "100.0",
"qtype": "SingleChoice",
"sId": "28568"
}
}
},
"paperType": "1",
"paperOid": "28567",
"instanceId": 30823,
"remainingTime": -1,
"examOid": "28570"
}

获取“userAnswer”的value,再转成JSON,可仿照如下形式：
JSONObject userJson = JSONObject.parseObject(jsonObject.getString("userAnswer"));
但是想获取key"28568"就没这么容易了。直接像上述的写法，会报错。
我们浏览fastjson中的源码，总结下，应该如下写：
JSONObject question = (JSONObject) JSONObject.parseObject(section.getString("28568"), Object.class);
整体代码：

dao代码很容易，就不贴出来了。

 1 package com.xiamenair.training.business.service;
 2 import com.alibaba.fastjson.JSONObject;
 3 import com.xiamenair.training.business.dao.elearningdao.ELearningExamInstanceDao;
 4 import com.xiamenair.training.business.dao.masterdao.ELearningChoiceRecordDao;
 5 import com.xiamenair.training.business.model.LasChoiceRecord;
 6 import com.xiamenair.training.business.model.entity.elearning.LasExamInstance;
 7 import org.springframework.beans.factory.annotation.Autowired;
 8 import org.springframework.scheduling.annotation.Scheduled;
 9 import org.springframework.stereotype.Service;
10 import java.math.BigDecimal;
11 import java.sql.Blob;
12 import java.sql.SQLException;
13 import java.text.SimpleDateFormat;
14 import java.util.*;
15 @Service
16 public class ChoiceRecordService {
17 //查询数据Dao
18 @Autowired
19 private ELearningChoiceRecordDao eLearningChoiceRecordDao;
20 //转储数据Dao
21 @Autowired
22 private ELearningExamInstanceDao eLearningExamInstanceDao;
23 private ChoiceRecordService() {
24 }
25 private static class SingletonRecordInstance {
26 private static final LasChoiceRecord choiceRecord = new LasChoiceRecord();
27 }
28 public static LasChoiceRecord getMapInstance() {
29 return SingletonRecordInstance.choiceRecord;
30 }
31 private static SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
32 /**
33 * 定时任务，每天定时将E学网考试数据分析并转储
34 *
35 * @param : instanceIdList
36 * @return : void
37 * @author : 28370·皮育才
38 * @date : 2018/11/20
39 **/
40 @Scheduled(cron = "00 00 01 * * ?")
41 public void analysisChoiceRecord() {
42 //获取前一天的时间
43 Date date = new Date();
44 Calendar calendar = Calendar.getInstance();
45 calendar.setTime(date);
46 calendar.add(calendar.DATE, -1);
47 date = calendar.getTime();
48 String dateString = simpleDateFormat.format(date);
49 List<BigDecimal> instanceIdList = eLearningExamInstanceDao.findInstanceIdByFinishTime(dateString);
50 if(0 != instanceIdList.size()){
51 LasChoiceRecord lasChoiceRecord = getMapInstance();
52 instanceIdList.stream().forEach(instanceId -> {
53 Blob answerBlob = eLearningExamInstanceDao.findUserAnswer(instanceId);
54 Long userId = eLearningExamInstanceDao.findUserId(instanceId);
55 String content = null;
56 try {
57 content = new String(answerBlob.getBytes((long) 1, (int) answerBlob.length()));
58 } catch (SQLException e) {
59 e.printStackTrace();
60 System.out.println("SQLEXCEPTION:" + e);
61 }
62 JSONObject jsonObject = JSONObject.parseObject(content);
63 //针对本section的"公共"属性直接设置
64 lasChoiceRecord.setUserId(userId);
65 lasChoiceRecord.setPaperType(jsonObject.getString("paperType"));
66 lasChoiceRecord.setPaperId(jsonObject.getString("paperOid"));
67 lasChoiceRecord.setExamInstanceId(jsonObject.getString("instanceId"));
68 lasChoiceRecord.setRemainingTime(jsonObject.getString("remainingTime"));
69 lasChoiceRecord.setExamId(jsonObject.getString("examOid"));
70 //针对section中的题目进行细化循环拆分
71 JSONObject userJson = JSONObject.parseObject(jsonObject.getString("userAnswer"));
72 Set sectionSet = userJson.keySet();
73 Iterator<String> setIt = sectionSet.iterator();
74 analyzeAnswer(lasChoiceRecord, userJson, setIt);
75 });
76 }
77 }
78 private void analyzeAnswer(LasChoiceRecord lasChoiceRecord, JSONObject userJson, Iterator<String> setIt) {
79 while (setIt.hasNext()) {
80 //对每个question进行再次拆分出题目
81 JSONObject section = (JSONObject) JSONObject.parseObject(userJson.getString(setIt.next()), Object.class);
82 Set questionSet = section.keySet();
83 Iterator<String> queIt = questionSet.iterator();
84 while (queIt.hasNext()) {
85 JSONObject question = (JSONObject) JSONObject.parseObject(section.getString(queIt.next()), Object.class);
86 String userAnswer = question.getString("answer");
87 String userScore = question.getString("userScore");
88 lasChoiceRecord.setQuestionId(question.getString("qId"));
89 lasChoiceRecord.setRecordId(UUID.randomUUID().toString());
90 eLearningChoiceRecordDao.save(lasChoiceRecord);
91 }
92 }
93 }
94 }