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qt6 通过http查询天气的实现_qt6 天气预报

作者：一键难忘520 | 2024-07-28 10:51:38

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qt6 天气预报

步骤如下： 

  1. cmakelist 当中，增加如下配置
  2.  引入包
  3.  访问远端api
  4.  解析返回的数据

  1. cmakelist 当中，增加如下配置，作用是引入Network库。
    2.  引入包

 3、访问远端api

  1. void Form1::on_pushButton_clicked()
  2. {
  3.     //根据URL(http://t.weather.itboy.net/api/weather/city/101010100)http请求查询温度信息
  4.     QNetworkAccessManager *manager = new QNetworkAccessManager(this);   //网络管理器
  5.     QNetworkRequest request;   //请求
  6.     request.setUrl(QUrl("http://t.weather.itboy.net/api/weather/city/101010100"));   //设置url
  7.     QNetworkReply *reply = manager->get(request); //发送get请求
  8.     connect(reply, &QNetworkReply::finished, [=](){   //请求完成后的处理
  9.         if(reply->error() == QNetworkReply::NoError)  
  10.         {
  11.             QByteArray data = reply->readAll();
  12.             QJsonParseError json_error;
  13.             QJsonDocument doc = QJsonDocument::fromJson(data, &json_error);  //解析json数据
  14.             if(json_error.error == QJsonParseError::NoError)  
  15.             {
  16.                 if(doc.isObject())  
  17.                 {
  18.                     QJsonObject obj = doc.object();  //获取json对象
  19.                     if(obj.contains("data"))  //判断是否包含data
  20.                     {
  21.                         QJsonValue value = obj.value("data");  //获取data数据
  22.                         if(value.isObject())
  23.                         {
  24.                             QJsonObject data = value.toObject();  //获取data对象
  25.                             if(data.contains("wendu"))   //判断是否包含wendu
  26.                             {
  27.                                 QJsonValue wendu = data.value("wendu");   //获取温度
  28.                                 ui->label->setText("温度：" + wendu.toString());  //显示温度
  29.                             }
  30.                         }
  31.                     }
  32.                 }
  33.             }
  34.         }
  35.         reply->deleteLater();  //释放资源  这个很重要！！！
  36.     });
  37.  
  38.  
  39. }

这段代码是在Qt框架中，特别是使用Qt Network模块，来实现一个HTTP GET请求以查询指定城市的天气温度信息。这里详细解释每一步的作用和目的：

  1. 创建QNetworkAccessManager实例：

  2. QNetworkAccessManager *manager = new QNetworkAccessManager(this);

    QNetworkAccessManager是Qt中用于发送网络请求的类。这里创建了一个QNetworkAccessManager的实例，并将this（假设是某个QWidget或QObject的子类，如Form1）作为父对象。这样做可以确保当Form1被销毁时，QNetworkAccessManager也会被正确地销毁。

  3. 设置请求：

    1. QNetworkRequest request; 
    2. request.setUrl(QUrl("http://t.weather.itboy.net/api/weather/city/101010100"));

    创建一个QNetworkRequest对象并设置其URL为需要查询的天气API的URL。这里假设URL是正确的，并且服务器会返回JSON格式的天气数据。

  5. 发送GET请求：

  6. QNetworkReply *reply = manager->get(request);

    通过QNetworkAccessManager的get方法发送GET请求。这个方法返回一个QNetworkReply对象的指针，该对象将用于后续处理HTTP响应。

  7. 处理响应：
    使用connect函数将QNetworkReply的finished信号连接到一个lambda表达式，该表达式在请求完成时执行。

    • 检查错误：首先检查响应中是否有错误。如果没有错误（QNetworkReply::NoError），则继续处理数据。
    • 读取并解析JSON数据：使用readAll方法读取响应数据，然后尝试使用QJsonDocument::fromJson方法解析这些数据为QJsonDocument对象。解析过程中，QJsonParseError对象用于捕获任何可能的解析错误。
    • 遍历JSON对象：解析成功后，检查JSON文档是否是一个对象，并遍历它以查找包含温度信息的data字段。如果找到data字段，并且它是一个对象，则进一步查找wendu（温度）字段。
    • 显示温度：如果找到wendu字段，将其值转换为字符串，并设置到UI的某个标签（假设为ui->label）上。

  8. 资源释放：

  9. reply->deleteLater();

    在lambda表达式的末尾调用deleteLater方法。这是为了确保在lambda表达式执行完毕后，QNetworkReply对象能够被正确地删除。这是因为QNetworkReply对象在响应完成后仍然占用内存，直接删除可能会导致问题，而deleteLater会将其放入事件循环中稍后删除。

注意：

  • 我们图形化界面中 ui->label。
  • 这段代码API返回的数据格式是已知的，
  1. {
  2.     "message": "success感谢又拍云(upyun.com)提供CDN赞助",
  3.     "status": 200,
  4.     "date": "20240703",
  5.     "time": "2024-07-03 19:15:24",
  6.     "cityInfo": {
  7.         "city": "北京市",
  8.         "citykey": "101010100",
  9.         "parent": "北京",
  10.         "updateTime": "15:46"
  11.     },
  12.     "data": {
  13.         "shidu": "51%",
  14.         "pm25": 31.0,
  15.         "pm10": 42.0,
  16.         "quality": "优",
  17.         "wendu": "28.6",
  18.         "ganmao": "各类人群可自由活动",
  19.         "forecast": [
  20.             {
  21.                 "date": "03",
  22.                 "high": "高温 31℃",
  23.                 "low": "低温 17℃",
  24.                 "ymd": "2024-07-03",
  25.                 "week": "星期三",
  26.                 "sunrise": "04:50",
  27.                 "sunset": "19:46",
  28.                 "aqi": 67,
  29.                 "fx": "南风",
  30.                 "fl": "2级",
  31.                 "type": "晴",
  32.                 "notice": "愿你拥有比阳光明媚的心情"
  33.             },
  34.             {
  35.                 "date": "04",
  36.                 "high": "高温 30℃",
  37.                 "low": "低温 21℃",
  38.                 "ymd": "2024-07-04",
  39.                 "week": "星期四",
  40.                 "sunrise": "04:51",
  41.                 "sunset": "19:46",
  42.                 "aqi": 85,
  43.                 "fx": "东南风",
  44.                 "fl": "2级",
  45.                 "type": "小雨",
  46.                 "notice": "雨虽小，注意保暖别感冒"
  47.             },
  48.             {
  49.                 "date": "05",
  50.                 "high": "高温 32℃",
  51.                 "low": "低温 22℃",
  52.                 "ymd": "2024-07-05",
  53.                 "week": "星期五",
  54.                 "sunrise": "04:51",
  55.                 "sunset": "19:46",
  56.                 "aqi": 94,
  57.                 "fx": "西南风",
  58.                 "fl": "2级",
  59.                 "type": "多云",
  60.                 "notice": "阴晴之间，谨防紫外线侵扰"
  61.             },
  62.             {
  63.                 "date": "06",
  64.                 "high": "高温 29℃",
  65.                 "low": "低温 23℃",
  66.                 "ymd": "2024-07-06",
  67.                 "week": "星期六",
  68.                 "sunrise": "04:52",
  69.                 "sunset": "19:45",
  70.                 "aqi": 84,
  71.                 "fx": "东北风",
  72.                 "fl": "2级",
  73.                 "type": "小雨",
  74.                 "notice": "雨虽小，注意保暖别感冒"
  75.             },
  76.             {
  77.                 "date": "07",
  78.                 "high": "高温 32℃",
  79.                 "low": "低温 23℃",
  80.                 "ymd": "2024-07-07",
  81.                 "week": "星期日",
  82.                 "sunrise": "04:53",
  83.                 "sunset": "19:45",
  84.                 "aqi": 84,
  85.                 "fx": "南风",
  86.                 "fl": "2级",
  87.                 "type": "阴",
  88.                 "notice": "不要被阴云遮挡住好心情"
  89.             },
  90.             {
  91.                 "date": "08",
  92.                 "high": "高温 35℃",
  93.                 "low": "低温 23℃",
  94.                 "ymd": "2024-07-08",
  95.                 "week": "星期一",
  96.                 "sunrise": "04:53",
  97.                 "sunset": "19:45",
  98.                 "aqi": 77,
  99.                 "fx": "西南风",
  100.                 "fl": "2级",
  101.                 "type": "晴",
  102.                 "notice": "愿你拥有比阳光明媚的心情"
  103.             },
  104.             {
  105.                 "date": "09",
  106.                 "high": "高温 34℃",
  107.                 "low": "低温 24℃",
  108.                 "ymd": "2024-07-09",
  109.                 "week": "星期二",
  110.                 "sunrise": "04:54",
  111.                 "sunset": "19:44",
  112.                 "aqi": 62,
  113.                 "fx": "东南风",
  114.                 "fl": "1级",
  115.                 "type": "大雨",
  116.                 "notice": "出门最好穿雨衣，勿挡视线"
  117.             },
  118.             {
  119.                 "date": "10",
  120.                 "high": "高温 34℃",
  121.                 "low": "低温 25℃",
  122.                 "ymd": "2024-07-10",
  123.                 "week": "星期三",
  124.                 "sunrise": "04:55",
  125.                 "sunset": "19:44",
  126.                 "aqi": 61,
  127.                 "fx": "东北风",
  128.                 "fl": "2级",
  129.                 "type": "小雨",
  130.                 "notice": "雨虽小，注意保暖别感冒"
  131.             },
  132.             {
  133.                 "date": "11",
  134.                 "high": "高温 34℃",
  135.                 "low": "低温 26℃",
  136.                 "ymd": "2024-07-11",
  137.                 "week": "星期四",
  138.                 "sunrise": "04:55",
  139.                 "sunset": "19:44",
  140.                 "aqi": 58,
  141.                 "fx": "东南风",
  142.                 "fl": "2级",
  143.                 "type": "多云",
  144.                 "notice": "阴晴之间，谨防紫外线侵扰"
  145.             },
  146.             {
  147.                 "date": "12",
  148.                 "high": "高温 30℃",
  149.                 "low": "低温 25℃",
  150.                 "ymd": "2024-07-12",
  151.                 "week": "星期五",
  152.                 "sunrise": "04:56",
  153.                 "sunset": "19:43",
  154.                 "aqi": 63,
  155.                 "fx": "东南风",
  156.                 "fl": "2级",
  157.                 "type": "阴",
  158.                 "notice": "不要被阴云遮挡住好心情"
  159.             },
  160.             {
  161.                 "date": "13",
  162.                 "high": "高温 35℃",
  163.                 "low": "低温 25℃",
  164.                 "ymd": "2024-07-13",
  165.                 "week": "星期六",
  166.                 "sunrise": "04:57",
  167.                 "sunset": "19:43",
  168.                 "aqi": 47,
  169.                 "fx": "东南风",
  170.                 "fl": "2级",
  171.                 "type": "阴",
  172.                 "notice": "不要被阴云遮挡住好心情"
  173.             },
  174.             {
  175.                 "date": "14",
  176.                 "high": "高温 35℃",
  177.                 "low": "低温 25℃",
  178.                 "ymd": "2024-07-14",
  179.                 "week": "星期日",
  180.                 "sunrise": "04:57",
  181.                 "sunset": "19:42",
  182.                 "aqi": 66,
  183.                 "fx": "东南风",
  184.                 "fl": "2级",
  185.                 "type": "多云",
  186.                 "notice": "阴晴之间，谨防紫外线侵扰"
  187.             },
  188.             {
  189.                 "date": "15",
  190.                 "high": "高温 32℃",
  191.                 "low": "低温 23℃",
  192.                 "ymd": "2024-07-15",
  193.                 "week": "星期一",
  194.                 "sunrise": "04:58",
  195.                 "sunset": "19:42",
  196.                 "aqi": 61,
  197.                 "fx": "东风",
  198.                 "fl": "2级",
  199.                 "type": "中雨",
  200.                 "notice": "记得随身携带雨伞哦"
  201.             },
  202.             {
  203.                 "date": "16",
  204.                 "high": "高温 30℃",
  205.                 "low": "低温 21℃",
  206.                 "ymd": "2024-07-16",
  207.                 "week": "星期二",
  208.                 "sunrise": "04:59",
  209.                 "sunset": "19:41",
  210.                 "aqi": 54,
  211.                 "fx": "东风",
  212.                 "fl": "2级",
  213.                 "type": "中雨",
  214.                 "notice": "记得随身携带雨伞哦"
  215.             },
  216.             {
  217.                 "date": "17",
  218.                 "high": "高温 35℃",
  219.                 "low": "低温 23℃",
  220.                 "ymd": "2024-07-17",
  221.                 "week": "星期三",
  222.                 "sunrise": "05:00",
  223.                 "sunset": "19:40",
  224.                 "aqi": 46,
  225.                 "fx": "西南风",
  226.                 "fl": "2级",
  227.                 "type": "多云",
  228.                 "notice": "阴晴之间，谨防紫外线侵扰"
  229.             }
  230.         ],
  231.         "yesterday": {
  232.             "date": "02",
  233.             "high": "高温 25℃",
  234.             "low": "低温 17℃",
  235.             "ymd": "2024-07-02",
  236.             "week": "星期二",
  237.             "sunrise": "04:50",
  238.             "sunset": "19:46",
  239.             "aqi": 25,
  240.             "fx": "北风",
  241.             "fl": "2级",
  242.             "type": "小雨",
  243.             "notice": "雨虽小，注意保暖别感冒"
  244.         }
  245.     }
  246. }
  • 由于网络请求是异步的，用户界面不会阻塞，这提供了更好的用户体验。槽函数在这里功不可没！另外 感谢哈工程大学通讯专业的同学，上面代码不是我写的：)

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