1 JSON数据简介
JSON(JavaScript Object Notation, JS 对象简谱) 是一种轻量级的数据交换格式。它基于 ECMAScript (欧洲计算机协会制定的js规范)的一个子集，采用完全独立于编程语言的文本格式来存储和表示数据。简洁和清晰的层次结构使得 JSON 成为理想的数据交换语言。 易于人阅读和编写，同时也易于机器解析和生成，并有效地提升网络传输效率。
JSON解析一定要掌握的两条规则：
1.如果看到是{ }–>使用JSONObject
2.如果看到的[ ]–>使用JSONArray解析
2 Qt中的JSON操作
3 DEMO
以和风天气的常规天气数据集合为例来解析JSON数据，原始的JSON数据显示到textEdit中
可以将原始的JSON数据复制到 http://www.bejson.com/ 进行解析，解析的结果如下:
{"HeWeather6":[{"basic":{"cid":"CN101050116","location":"道外","parent_city":"哈尔滨","admin_area":"黑龙江","cnty":"中国","lat":"45.78453827","lon":"126.64883423","tz":"+8.00"},"update":{"loc":"2018-09-26 15:45","utc":"2018-09-26 07:45"},"status":"ok","now":{"cloud":"25","cond_code":"100","cond_txt":"晴","fl":"18","hum":"52","pcpn":"0.0","pres":"1022","tmp":"19","vis":"10","wind_deg":"122","wind_dir":"东南风","wind_sc":"1","wind_spd":"5"},"daily_forecast":[{"cond_code_d":"100","cond_code_n":"100","cond_txt_d":"晴","cond_txt_n":"晴","date":"2018-09-26","hum":"61","mr":"18:18","ms":"06:07","pcpn":"0.0","pop":"2","pres":"1024","sr":"05:26","ss":"17:21","tmp_max":"20","tmp_min":"6","uv_index":"6","vis":"20","wind_deg":"193","wind_dir":"西南风","wind_sc":"3-4","wind_spd":"20"},{"cond_code_d":"101","cond_code_n":"100","cond_txt_d":"多云","cond_txt_n":"晴","date":"2018-09-27","hum":"61","mr":"18:44","ms":"07:13","pcpn":"0.0","pop":"25","pres":"1023","sr":"05:27","ss":"17:19","tmp_max":"20","tmp_min":"8","uv_index":"3","vis":"20","wind_deg":"170","wind_dir":"南风","wind_sc":"3-4","wind_spd":"12"},{"cond_code_d":"305","cond_code_n":"101","cond_txt_d":"小雨","cond_txt_n":"多云","date":"2018-09-28","hum":"70","mr":"19:14","ms":"08:20","pcpn":"6.0","pop":"80","pres":"1018","sr":"05:29","ss":"17:17","tmp_max":"18","tmp_min":"10","uv_index":"2","vis":"20","wind_deg":"160","wind_dir":"东南风","wind_sc":"3-4","wind_spd":"12"}],"lifestyle":[{"type":"comf","brf":"舒适","txt":"白天不太热也不太冷，风力不大，相信您在这样的天气条件下，应会感到比较清爽和舒适。"},{"type":"drsg","brf":"较舒适","txt":"建议着薄外套、开衫牛仔衫裤等服装。年老体弱者应适当添加衣物，宜着夹克衫、薄毛衣等。"},{"type":"flu","brf":"较易发","txt":"天气较凉，较易发生感冒，请适当增加衣服。体质较弱的朋友尤其应该注意防护。"},{"type":"sport","brf":"较适宜","txt":"天气较好，但因风力稍强，户外可选择对风力要求不高的运动，推荐您进行室内运动。"},{"type":"trav","brf":"适宜","txt":"天气较好，风稍大，但温度适宜，是个好天气哦。适宜旅游，您可以尽情地享受大自然的无限风光。"},{"type":"uv","brf":"中等","txt":"属中等强度紫外线辐射天气，外出时建议涂擦SPF高于15、PA+的防晒护肤品，戴帽子、太阳镜。"},{"type":"cw","brf":"较适宜","txt":"较适宜洗车，未来一天无雨，风力较小，擦洗一新的汽车至少能保持一天。"},{"type":"air","brf":"良","txt":"气象条件有利于空气污染物稀释、扩散和清除，可在室外正常活动。"}]}]}代码如下
.pro文件
#-------------------------------------------------## Project created by QtCreator 2018-09-21T21:19:38##-------------------------------------------------QT ??????+= core guiQT ??????+= networkgreaterThan(QT_MAJOR_VERSION, 4): QT += widgetsTARGET = myHTTPTEMPLATE = appSOURCES += main.cpp ???????mainwindow.cppHEADERS ?+= mainwindow.hFORMS ???+= mainwindow.uimainwindow.h
#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QMainWindow>#include <QNetworkReply>#include <QNetworkAccessManager>#include <QNetworkAccessManager>#include <QJsonParseError>#include <QJsonObject>#include <QJsonValue>#include <QDebug>#include <QJsonArray>namespace Ui {class MainWindow;}class MainWindow : public QMainWindow{ ???Q_OBJECTpublic: ???explicit MainWindow(QWidget *parent = 0); ???~MainWindow(); ???void DecodeJson(QString JsonData); //解析Json数据 ???QString cid; ???QString location; ???QString parent_city; ???QString loc; ???QString status; ???QString cond_code_d; ???QString cond_txt_d; ???QString cmf; ???QString air;private: ???QNetworkAccessManager *manager; ???Ui::MainWindow *ui;private slots: ???void replyFinished(QNetworkReply *);};#endif // MAINWINDOW_H mainwindow.h中声明了几个变量，一个用来解析Json数据的函数，一个槽函数，仅此而已。
mainwindow.cpp
#include "mainwindow.h"#include "ui_mainwindow.h"#define WEATHER_URL "https://free-api.heweather.com/s6/weather?location=CN101050116&key=0db7704826964aabafc351a52384225b"MainWindow::MainWindow(QWidget *parent) : ???QMainWindow(parent), ???ui(new Ui::MainWindow){ ???ui->setupUi(this); ???manager=new QNetworkAccessManager(this); ???connect(manager,SIGNAL(finished(QNetworkReply*)), ???????????this,SLOT(replyFinished(QNetworkReply*))); ???manager->get(QNetworkRequest(QUrl(WEATHER_URL)));}void MainWindow::replyFinished(QNetworkReply *reply){ ???QString all=reply->readAll(); ?//all数据只用来显示 ???ui->textEdit->setText(all); ???DecodeJson(all); ???reply->deleteLater();}//用来解析Jsong数据void MainWindow::DecodeJson(QString JsonData){ ???QJsonParseError json_error; ???QByteArray byteArray = JsonData.toUtf8(); ???//转换为JsonDoucument文档 ???QJsonDocument json_doucment = QJsonDocument::fromJson(byteArray, &json_error); ???if(json_error.error != QJsonParseError::NoError) ???{ ???????qDebug()<<"解析数据错误"<<endl; ???????return ; ???} ???QJsonArray json_array; ???if(json_doucment.object().contains("HeWeather6")) ???{ ???????qDebug()<<"HeWeather6"<<endl; ???????json_array=json_doucment.object().value("HeWeather6").toArray(); ???} ???QJsonObject main_json_data=json_array.at(0).toObject(); ???if(main_json_data.contains("basic")) ???{ ???????QJsonObject basc_json_data=main_json_data.value("basic").toObject(); ???????cid=basc_json_data.value("cid").toString(); ???????location=basc_json_data.value("location").toString(); ???????parent_city=basc_json_data.value("parent_city").toString(); ???????qDebug()<<cid<<endl; ???????qDebug()<<parent_city<<endl; ???} ???if(main_json_data.contains("update")) ???{ ???????QJsonObject update_json_data=main_json_data.value("update").toObject(); ???????loc=update_json_data.value("loc").toString(); ???????qDebug()<<loc<<endl; ???} ???if(main_json_data.contains("status")) ???{ ???????status=main_json_data.value("status").toString(); ???????qDebug()<<status<<endl; ???} ???if(main_json_data.contains("now")) ???{ ???} ???if(main_json_data.contains("daily_forecast")) ???{ ???????qDebug()<<"daily_forecast"<<endl; ???????QJsonArray daily_forecast_array=main_json_data.value("daily_forecast").toArray(); ???????//Today天气 ???????QJsonObject today_forecast=daily_forecast_array.at(0).toObject(); ???????cond_code_d=today_forecast.value("cond_code_d").toString(); ???????cond_txt_d=today_forecast.value("cond_txt_d").toString(); ???????qDebug()<<cond_code_d<<endl; ???????qDebug()<<"cond_txt_d="<<cond_txt_d<<endl; ???????//Tomorrow天气 ???????QJsonObject tomorrow_forecast=daily_forecast_array.at(1).toObject(); ???????cond_code_d=tomorrow_forecast.value("cond_code_d").toString(); ???????cond_txt_d=tomorrow_forecast.value("cond_txt_d").toString(); ???????qDebug()<<cond_code_d<<endl; ???????qDebug()<<"cond_txt_d="<<cond_txt_d<<endl; ???} ???if(main_json_data.contains("lifestyle")) ???{ ???????QJsonArray lifestyle_json_array=main_json_data.value("lifestyle").toArray(); ???????QJsonObject comf_josn_object=lifestyle_json_array.at(0).toObject(); ???????cmf=comf_josn_object.value("txt").toString(); ???????qDebug()<<cmf<<endl; ???????QJsonObject air_josn_object=lifestyle_json_array.at(7).toObject(); ???????air=air_josn_object.value("txt").toString(); ???????qDebug()<<air<<endl; ???}}MainWindow::~MainWindow(){ ???delete ui;}mian.cpp
/* * 程序说明： * ????以和风天气的常规天气数据集合为例，解析Json数据*/#include "mainwindow.h"#include <QtNetwork>#include <QApplication>int main(int argc, char *argv[]){ ???QApplication a(argc, argv); ???MainWindow w; ???w.show(); ???return a.exec();} 解析出来的数据用qDebug()打印出来，可以和刚才的数据比较一下，看解析的是否正确
参考资料
和风天气 https://www.heweather.com/documents/api/s6/weather
Qt中的JSON操作 https://blog.csdn.net/Amnes1a/article/details/68957112
JSON的三种解析方式 https://www.cnblogs.com/zhujiabin/p/5498272.html
这一篇文章写的很好 https://blog.csdn.net/miaozhenzhong/article/details/52585726
JSON数据在线解析 http://www.bejson.com/
偷懒不想写了2018/9/26
Qt解析Json数据
原文地址：https://www.cnblogs.com/Manual-Linux/p/9693308.html