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上一篇介绍了C语言写的JSON解析库cJSON的使用：使用cJSON库解析和构建JSON字符串
本篇文章介绍，Qt开发环境下QJson库的使用示例，JSON解析配合API接口，就可以实现一些有趣的工具了，如全国油价查询工具，全国天气查询，空气质量查询，黄历查询，生活指数等等实用工具的开发。
分享几个免费的API提供平台：
示例代码包含简单和复杂JSON字符串的解析和构建，Qt工程已经开源在Github和Gitee代码托管平台。
开发平台基于Qt 5.8 Windows。
示例的JSON字符串和上一篇使用的是一样的。
JSON解析示例包括：
JSON的构建：
JSON的解析要对照JSON字符串来理解，关于JSON字符串的介绍，可以参考JSON简介
首先，解析和构建都要包含如下头文件：
#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>这个JSON字符串中HeWeather6键的值是一个数组，数组内只有1个JSON对象，这个对象里又嵌套了几个JSON对象。
{
"HeWeather6": [{
"basic": {
"cid": "CN101010700",
"location": "昌平",
"parent_city": "北京",
"admin_area": "北京",
"cnty": "中国",
"lat": "40.21808624",
"lon": "116.23590851",
"tz": "+8.00"
},
"update": {
"loc": "2019-07-20 10:21",
"utc": "2019-07-20 02:21"
},
"status": "ok",
"now": {
"cloud": "96",
"cond_code": "104",
"cond_txt": "阴",
"fl": "28",
"hum": "86",
"pcpn": "0.0",
"pres": "995",
"tmp": "25",
"vis": "4",
"wind_deg": "100",
"wind_dir": "东风",
"wind_sc": "1",
"wind_spd": "4"
}
}]
}字符串1解析函数
主要是JSON的多层嵌套的解析。
int Parse_HeWeather_Now_Json(void)
{
QJsonParseError err_rpt;
QJsonDocument root_Doc = QJsonDocument::fromJson(he_now_json, &err_rpt);//字符串格式化为JSON
if(err_rpt.error != QJsonParseError::NoError)
{
qDebug() << "JSON格式错误";
return -1;
}
else //JSON格式正确
{
// qDebug() << "JSON格式正确：\n" << root_Doc;
QJsonObject root_Obj = root_Doc.object();
QJsonValue weather_Value = root_Obj.value("HeWeather6"); //HeWeather6键的值，是一个数组
if(weather_Value.isArray()) //可省略
{
QJsonObject weather_Obj = weather_Value.toArray().at(0).toObject(); //HeWeather6数组就含有一个元素0
/* basic键信息 */
QJsonObject basic_Obj = weather_Obj.value("basic").toObject();
QString cid = basic_Obj.value("cid").toString();
QString location = basic_Obj.value("location").toString();
QString parent_city = basic_Obj.value("parent_city").toString();
QString cnty = basic_Obj.value("cnty").toString();
QString lat = basic_Obj.value("lat").toString();
QString lon = basic_Obj.value("lon").toString();
QString basic_info = cid + " " + parent_city + " " + cnty + " " + lat + " " + lon;
qDebug() << basic_info;
/* update键信息 */
QJsonObject update_Obj = weather_Obj.value("update").toObject();
QString loc = "当地时间:" + update_Obj.value("loc").toString(); //当地时间
QString utc = "UTC时间:" + update_Obj.value("utc").toString(); //UTC时间
QString status = "解析状态:" + weather_Obj.value("status").toString(); //"ok"
qDebug() << loc + " " + utc + " " + status;
/* now键信息*/
QJsonObject now_Obj = weather_Obj.value("now").toObject();
QString cond_txt = "白天天气:" + now_Obj.value("cond_txt").toString();
QString hum = "湿度:" + now_Obj.value("hum").toString();
QString tmp = "温度:" + now_Obj.value("tmp").toString();
QString wind_dir = "风向:" + now_Obj.value("wind_dir").toString();
QString wind_sc = "风级:" + now_Obj.value("wind_sc").toString();
qDebug() << cond_txt + " " + hum + " " + tmp + " " + wind_dir + " " + wind_sc;
}
qDebug() << "解析完成!";
}
return 0;
}这个字符串和上面那个一样，都是数组元素是JSON对象，对象的值又是一个JSON对象。
{
"results": [{
"location": {
"id": "WX4FBXXFKE4F",
"name": "北京",
"country": "CN",
"path": "北京,北京,中国",
"timezone": "Asia/Shanghai",
"timezone_offset": "+08:00"
},
"now": {
"text": "晴",
"code": "1",
"temperature": "-7"
},
"last_update": "2018-12-06T22:05:00+08:00"
}]
}字符串2解析函数
int Parse_Seniverse_Now_Json(void)
{
QJsonParseError err_rpt;
QJsonDocument root_Doc = QJsonDocument::fromJson(seniverse_now_json, &err_rpt);//字符串格式化为JSON
if(err_rpt.error != QJsonParseError::NoError)
{
qDebug() << "JSON格式错误";
return -1;
}
else //JSON格式正确
{
// qDebug() << "JSON格式正确：\n" << root_Doc;
QJsonObject root_Obj = root_Doc.object();
QJsonValue result_Value = root_Obj.value("results");
if(result_Value.isArray())
{
QJsonObject result_Obj = result_Value.toArray().at(0).toObject();
QString last_update = result_Obj.value("last_update").toString();
qDebug() << last_update;
/* location键的值 */
QJsonObject location_Obj = result_Obj.value("location").toObject();
QString id = location_Obj.value("id").toString();
QString name = location_Obj.value("name").toString();
QString timezone = location_Obj.value("timezone").toString();
QString path = location_Obj.value("path").toString();
QString loc_str = id + " " + name + " " + timezone + " " + path ;
qDebug() << loc_str;
/* now键 */
QJsonObject now_Obj = result_Obj.value("now").toObject();
QString code = "天气代码: " + now_Obj.value("code").toString();
QString temperature = "当前温度：" + now_Obj.value("temperature").toString();
QString text = "天气：" + now_Obj.value("text").toString();
qDebug() << code << temperature << text;
}
}
return 0;
}{
"results": [{
"location": {
"id": "WS10730EM8EV",
"name": "深圳",
"country": "CN",
"path": "深圳,深圳,广东,中国",
"timezone": "Asia/Shanghai",
"timezone_offset": "+08:00"
},
"daily": [{
"date": "2018-12-06",
"text_day": "阴",
"code_day": "9",
"text_night": "阴",
"code_night": "9",
"high": "25",
"low": "16",
"precip": "",
"wind_direction": "无持续风向",
"wind_direction_degree": "",
"wind_speed": "10",
"wind_scale": "2"
}, {
"date": "2018-12-07",
"text_day": "阴",
"code_day": "9",
"text_night": "小雨",
"code_night": "13",
"high": "20",
"low": "15",
"precip": "",
"wind_direction": "北",
"wind_direction_degree": "0",
"wind_speed": "15",
"wind_scale": "3"
}, {
"date": "2018-12-08",
"text_day": "小雨",
"code_day": "13",
"text_night": "小雨",
"code_night": "13",
"high": "17",
"low": "12",
"precip": "",
"wind_direction": "东北",
"wind_direction_degree": "45",
"wind_speed": "15",
"wind_scale": "3"
}],
"last_update": "2018-12-06T18:00:00+08:00"
}]
}字符串3解析函数
int Parse_Seniverse_Forecast_Json(void)
{
QJsonParseError err_rpt;
QJsonDocument root_Doc = QJsonDocument::fromJson(seniverse_forcast_json, &err_rpt);//字符串格式化为JSON
if(err_rpt.error != QJsonParseError::NoError)
{
qDebug() << "JSON格式错误";
return -1;
}
else //JSON格式正确
{
// qDebug() << "JSON格式正确：\n" << root_Doc;
QJsonObject root_Obj = root_Doc.object();
QJsonValue result_Value = root_Obj.value("results");
if(result_Value.isArray())
{
QJsonObject result_Obj = result_Value.toArray().at(0).toObject();
QString last_update = result_Obj.value("last_update").toString();
qDebug() << last_update;
/* location键的值 */
QJsonObject location_Obj = result_Obj.value("location").toObject();
QString id = location_Obj.value("id").toString();
QString name = location_Obj.value("name").toString();
QString timezone = location_Obj.value("timezone").toString();
QString path = location_Obj.value("path").toString();
QString loc_str = id + " " + name + " " + timezone + " " + path ;
qDebug() << loc_str;
/* daily预报天气3天，数组元素3个*/
QJsonValue daily_Vaule = result_Obj.value("daily");
if(daily_Vaule.isArray())
{
for(int idx = 0; idx <= 2; idx++)
{
QJsonObject daily_Obj = daily_Vaule.toArray().at(idx).toObject();
QString date = " 日期：" + daily_Obj.value("date").toString();
QString text_day =" 白天天气：" + daily_Obj.value("text_day").toString();
QString high = " 最高温度：" + daily_Obj.value("high").toString();
QString low = " 最低温度：" + daily_Obj.value("low").toString();
QString wind_direction = " 风向：" + daily_Obj.value("wind_direction").toString();
QString wind_scale = " 风级：" + daily_Obj.value("wind_scale").toString();
qDebug() << date + text_day + high + low + wind_direction + wind_scale;
}
}
}
}
return 0;
}包含10个元素的数组。
{
"status": "0",
"citye": "changchun",
"city": "长春",
"citycode": "101060101",
"aqi": "50",
"data": [{
"add": "长春",
"aqi": "50",
"pm25": "22",
"per": "优",
"lv": "1"
}, {
"add": "食品厂",
"aqi": "54",
"pm25": "18",
"per": "良",
"lv": "2"
}, {
"add": "客车厂",
"aqi": "52",
"pm25": "20",
"per": "良",
"lv": "2"
}, {
"add": "邮电学院",
"aqi": "35",
"pm25": "24",
"per": "优",
"lv": "1"
}, {
"add": "劳动公园",
"aqi": "45",
"pm25": "19",
"per": "优",
"lv": "1"
}, {
"add": "园林处",
"aqi": "45",
"pm25": "21",
"per": "优",
"lv": "1"
}, {
"add": "净月潭",
"aqi": "46",
"pm25": "30",
"per": "优",
"lv": "1"
}, {
"add": "甩湾子",
"aqi": "51",
"pm25": "24",
"per": "良",
"lv": "2"
}, {
"add": "经开区环卫处",
"aqi": "48",
"pm25": "25",
"per": "优",
"lv": "1"
}, {
"add": "高新区管委会",
"aqi": "51",
"pm25": "16",
"per": "良",
"lv": "2"
}, {
"add": "岱山公园",
"aqi": "49",
"pm25": "19",
"per": "优",
"lv": "1"
}]
}字符串4解析函数
int Parse_AQI_Json(void)
{
QJsonParseError err_rpt;
QJsonDocument root_Doc = QJsonDocument::fromJson(AQI_json, &err_rpt);//字符串格式化为JSON
if(err_rpt.error != QJsonParseError::NoError)
{
qDebug() << "JSON格式错误";
return -1;
}
else //JSON格式正确
{
// qDebug() << "JSON格式正确：\n" << root_Doc;
QJsonObject root_Obj = root_Doc.object();
QString city = root_Obj.value("city").toString();
QString citycode = root_Obj.value("citycode").toString();
QString citye = root_Obj.value("citye").toString();
QString status = root_Obj.value("status").toString();
qDebug() << city + " " + citycode + " " + citye + " " + status;
/* data键 */
QJsonValue data_Vaule = root_Obj.value("data");
if(data_Vaule.isArray())
{
for(int idx = 0; idx <= 10; idx++)
{
QJsonObject data_Obj = data_Vaule.toArray().at(idx).toObject();
QString add = "地址：" + data_Obj.value("add").toString();
QString aqi = " AQI：" + data_Obj.value("aqi").toString();
QString lv = " 空气质量等级：" + data_Obj.value("lv").toString();
QString per = " 空气质量：" + data_Obj.value("per").toString();
QString pm25 = " PM2.5等级：" + data_Obj.value("pm25").toString();
qDebug() << add + aqi + lv + per + pm25;
}
}
}
return 0;
}比较简单一个JSON对象
{
"success": "1",
"result": {
"timestamp": "1542456793",
"datetime_1": "2018-11-17 20:13:13",
"datetime_2": "2018年11月17日 20时13分13秒",
"week_1": "6",
"week_2": "星期六",
"week_3": "周六",
"week_4": "Saturday"
}
}字符串5解析函数
int Parse_BJTime_Json(void)
{
QJsonParseError err_rpt;
QJsonDocument root_Doc = QJsonDocument::fromJson(bj_time_json, &err_rpt);//字符串格式化为JSON
if(err_rpt.error != QJsonParseError::NoError)
{
qDebug() << "JSON格式错误";
return -1;
}
else //JSON格式正确
{
// qDebug() << "JSON格式正确：\n" << root_Doc;
QJsonObject root_Obj = root_Doc.object();
QString success = root_Obj.value("success").toString();
/* result键 */
QJsonObject result_Obj = root_Obj.value("result").toObject();
QString datetime_1 = result_Obj.value("datetime_1").toString();
QString datetime_2 = result_Obj.value("datetime_2").toString();
QString timestamp = result_Obj.value("timestamp").toString();
QString week_1 = result_Obj.value("week_1").toString();
QString week_2 = result_Obj.value("week_2").toString();
QString week_3 = result_Obj.value("week_3").toString();
QString week_4 = result_Obj.value("week_4").toString();
qDebug() << datetime_1 << datetime_2;
qDebug() << week_1 << week_2 << week_3 << week_4;
}
return 0;
}这种格式的字符串也是标准的JSON字符串，[]表示数组，这个数组内包含了5个字符串：
["北京", "6.78", "7.21", "8.19", "6.45"]但是这种不是，{}表示对象：
{"北京", "6.78", "7.21", "8.19", "6.45"}一个数组内包含5个元素，每个元素又是一个数组，每个数组又包含5个字符串，属于数组的嵌套：
{
"status": "0",
"msg": "全国各省份汽柴油价格信息",
"update": "2019-07-21",
"data": [
["地区", "92号", "95号", "98号", "0号柴油"],
["北京", "6.78", "7.21", "8.19", "6.45"],
["上海", "6.74", "7.17", "7.87", "6.39"],
["江苏", "6.75", "7.18", "8.06", "6.37"],
["天津", "6.77", "7.15", "8.07", "6.41"]
],
"About": "wcc",
"Home": "www.wangchaochao.top"
}字符串6解析函数
//解析数组嵌套的JSON字符串
int Parse_Oil_Price_Json(void)
{
QJsonParseError err_rpt;
QJsonDocument root_Doc = QJsonDocument::fromJson(oil_price_json, &err_rpt);//字符串格式化为JSON
if(err_rpt.error != QJsonParseError::NoError)
{
qDebug() << "JSON格式错误";
return -1;
}
else //JSON格式正确
{
// qDebug() << "JSON格式正确：\n" << root_Doc;
QJsonObject root_Obj = root_Doc.object();
QString msg = root_Obj.value("msg").toString();
QString update = root_Obj.value("update").toString();
QString status = root_Obj.value("status").toString();
QString About = root_Obj.value("About").toString();
QString Home = root_Obj.value("Home").toString();
qDebug() << msg << update << status << About << Home;
/* data键解析 */
QJsonValue data_Value = root_Obj.value("data");
if(data_Value.isArray()) //数组中包含5个数组，每个数组5个字符串元素
{
for(int idx = 0; idx <= 4; idx++)
{
QJsonValue price_Obj = data_Value.toArray().at(idx);
if(price_Obj.isArray())
{
QString str1 = price_Obj.toArray().at(0).toString();// 每个元素是一个字符串
QString str2 = price_Obj.toArray().at(1).toString();
QString str3 = price_Obj.toArray().at(2).toString();
QString str4 = price_Obj.toArray().at(3).toString();
QString str5 = price_Obj.toArray().at(4).toString();
qDebug() << str1 << str2 << str3 << str4 << str5 ;
}
}
}
}
return 0;
}void Create_Simple_JSON(void)
{
//创建JSON对象
QJsonObject root_Obj;
//添加键值对，值的类型自动识别，顺序不可自定义
root_Obj.insert("CSDN", "https://blog.csdn.net/whik1194");
root_Obj.insert("cnblogs", "https://home.cnblogs.com/u/whik/");
root_Obj.insert("Github", "https://github.com/whik/");
root_Obj.insert("Blog", "https://www.wangchaochao.top/");
root_Obj.insert("status", 1);
root_Obj.insert("enable", true);
root_Obj.insert("update_time", "20190723");
//创建Json文档
QJsonDocument root_Doc;
root_Doc.setObject(root_Obj);
QByteArray root_str = root_Doc.toJson(QJsonDocument::Compact); //紧凑格式
// QByteArray root_str = root_Doc.toJson(QJsonDocument::Indented); //标准JSON格式 QString strJson(root_str);
QString strJson(root_str);
qDebug() << strJson;
}输出结果
{
"Blog": "https://www.wangchaochao.top/",
"CSDN": "https://blog.csdn.net/whik1194",
"Github": "https://github.com/whik/",
"cnblogs": "https://home.cnblogs.com/u/whik/",
"enable": true,
"status": 1,
"update_time": "20190723"
}void Create_BJTime_JSON(void)
{
QJsonObject result_Obj;
result_Obj.insert("timestamp", "ok");
result_Obj.insert("datetime_1", "2019-07-21 10:46:57");
result_Obj.insert("datetime_2", "2019年07月21日 10时46分57秒");
result_Obj.insert("week_1", "0");
result_Obj.insert("week_2", "星期日");
result_Obj.insert("week_3", "周日");
result_Obj.insert("week_4", "Sunday");
QJsonObject root_Obj;
//添加键值对，值的类型自动识别，顺序不可自定义
root_Obj.insert("status", "success");
root_Obj.insert("Blog", "www.wangchaochao.top");
root_Obj.insert("result", result_Obj);
//创建Json文档
QJsonDocument root_Doc;
root_Doc.setObject(root_Obj);
QByteArray root_str = root_Doc.toJson(QJsonDocument::Compact); //紧凑格式
// QByteArray root_str = root_Doc.toJson(QJsonDocument::Indented); //标准JSON格式
// qDebug() << root_str; //中文输出乱码
QString strJson(root_str);
qDebug() << strJson;
}输出结果
{
"status": "success",
"result": {
"timestamp": "ok",
"datetime_1": "2019-07-21 10:46:57",
"datetime_2": "2019年07月21日 10时46分57秒",
"week_1": "0",
"week_2": "星期日",
"week_3": "周日",
"week_4": "Sunday"
},
"Blog": "www.wangchaochao.top"
}void Create_Array_Str_JSON(void)
{
QJsonArray root_Arr;
root_Arr.insert(0, "Sunday");
root_Arr.insert(1, "Monday");
root_Arr.insert(2, "Tuesday");
root_Arr.insert(3, "Wednesday");
root_Arr.insert(4, "Thursday");
root_Arr.insert(5, "Friday");
root_Arr.insert(6, "Saturday");
//创建Json文档
QJsonDocument root_Doc;
root_Doc.setArray(root_Arr);
QByteArray root_str = root_Doc.toJson(QJsonDocument::Compact); //紧凑格式
// QByteArray root_str = root_Doc.toJson(QJsonDocument::Indented); //标准JSON格式
// qDebug() << root_str; //中文输出乱码
QString strJson(root_str);
qDebug() << strJson;
}输出结果
["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]void Create_Array_JSON(void)
{
QJsonObject day0_Obj;
QJsonObject day1_Obj;
QJsonObject day2_Obj;
day0_Obj.insert("date", "2019-07-21");
day0_Obj.insert("cond_txt", "多云");
day0_Obj.insert("cond_code", "101");
day0_Obj.insert("hum", "23");
day0_Obj.insert("tmp_H", "31");
day0_Obj.insert("tmp_L", "25");
day1_Obj.insert("date", "2019-07-21");
day1_Obj.insert("cond_txt", "阵雨");
day1_Obj.insert("cond_code", "107");
day1_Obj.insert("hum", "44");
day1_Obj.insert("tmp_H", "30");
day1_Obj.insert("tmp_L", "26");
day2_Obj.insert("date", "2019-07-22");
day2_Obj.insert("cond_txt", "晴");
day2_Obj.insert("cond_code", "100");
day2_Obj.insert("hum", "20");
day2_Obj.insert("tmp_H", "33");
day2_Obj.insert("tmp_L", "26");
QJsonArray weather_Arr;
weather_Arr.insert(0, day0_Obj);
weather_Arr.insert(1, day1_Obj);
weather_Arr.insert(2, day2_Obj);
QJsonObject root_Obj;
root_Obj.insert("status", "ok");
root_Obj.insert("update", "2019-07-21 11:00");
root_Obj.insert("Blog", "www.wangchaochao.top");
root_Obj.insert("weather", weather_Arr); //数组作为weather键的值
//创建Json文档
QJsonDocument root_Doc;
root_Doc.setObject(root_Obj);
QByteArray root_str = root_Doc.toJson(QJsonDocument::Compact); //紧凑格式
// QByteArray root_str = root_Doc.toJson(QJsonDocument::Indented); //标准JSON格式
// qDebug() << root_str; //中文输出乱码
QString strJson(root_str);
qDebug() << strJson;
}输出结果
{
"status": "ok",
"weather": [{
"date": "2019-07-21",
"cond_txt": "多云",
"cond_code": "101",
"hum": "23",
"tmp_H": "31",
"tmp_L": "25"
}, {
"date": "2019-07-22",
"cond_txt": "晴",
"cond_code": "100",
"hum": "20",
"tmp_H": "33",
"tmp_L": "26"
}, {
"date": "2019-07-23",
"cond_txt": "阵雨",
"cond_code": "107",
"hum": "45",
"tmp_H": "32",
"tmp_L": "25"
}],
"update": "2019-07-21 11:00",
"Blog": "www.wangchaochao.top"
}void Create_Array_Nest_JSON(void)
{
QJsonArray table_Arr = {"地区", "92号汽油", "95号汽油", "98号汽油", "0号柴油"};
QJsonArray bj_Arr = {"北京", "6.78", "7.21", "8.19", "6.45"};
QJsonArray sh_Arr = {"上海", "6.74", "7.17", "7.87", "6.39"};
QJsonArray js_Arr = {"江苏", "6.75", "7.18", "8.06", "6.37"};
QJsonArray tj_Arr = {"天津", "6.77", "7.15", "8.07", "6.41"};
QJsonArray data_Arr; //数组内嵌套了5个数组
data_Arr.insert(0, table_Arr);
data_Arr.insert(1, bj_Arr);
data_Arr.insert(2, sh_Arr);
data_Arr.insert(3, js_Arr);
data_Arr.insert(4, tj_Arr);
QJsonObject root_Obj;
root_Obj.insert("status", "ok");
root_Obj.insert("msg", "全国各省份汽柴油价格信息");
root_Obj.insert("update", "2019-07-21");
root_Obj.insert("About", "wcc");
root_Obj.insert("Blog", "www.wangchaochao.top");
root_Obj.insert("data", data_Arr); //数组作为键的值
//创建Json文档
QJsonDocument root_Doc;
root_Doc.setObject(root_Obj);
QByteArray root_str = root_Doc.toJson(QJsonDocument::Compact); //紧凑格式
// QByteArray root_str = root_Doc.toJson(QJsonDocument::Indented); //标准JSON格式
// qDebug() << root_str; //中文输出乱码
QString strJson(root_str);
qDebug() << strJson;
}输出结果
{
"status": "ok",
"msg": "全国各省份汽柴油价格信息",
"update": "2019-07-21",
"data": [
["地区", "92号汽油", "95号汽油", "98号汽油", "0号柴油"],
["北京", "6.78", "7.21", "8.19", "6.45"],
["上海", "6.74", "7.17", "7.87", "6.39"],
["江苏", "6.75", "7.18", "8.06", "6.37"],
["天津", "6.77", "7.15", "8.07", "6.41"]
],
"About": "wcc",
"Blog": "www.wangchaochao.top"
}欢迎关注我的个人博客：www.wangchaochao.top
或微信扫码关注我的公众号
标签：mes 简单 参考 sda for scale 聚合数据 str1 仓库
原文地址：https://www.cnblogs.com/whik/p/11234889.html
