QT's http get request to get weather information

I. Introduction

• Qt usually obtains weather information by calling the interface of the weather server, and the interface can be searched online by itself.
• The interface for obtaining weather information in this article is: http://wthrcdn.etouch.cn/weather_mini, and the request parameter name is city (to obtain weather information of a city). The request method is get request.

2. Realize the effect

Select a city from the drop-down box to get weather information 

 

 3. Implementation steps

1. Add network class

Add a network class that uses the weather interface to the Qt pro file to request data through http.

QT       += network

2. Add related header files

//添加网络相关头文件
#include <QtNetwork/QNetworkReply>
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkRequest>

//添加JSON解析相关的头文件，因为从该服务器请求的天气数据是以json的形式回复的
#include <QJsonArray>
#include <QJsonDocument>
#include <QJsonObject>

3. Create a network request object, connect signals and slots

After defining the relevant variables, connect the signal and slot in the constructor

    manager = new QNetworkAccessManager(this);  //新建QNetworkAccessManager对象
    //当收到http请求回复的数据，便会调用replyDone槽函数。
    //关联信号和槽
connect(manager,SIGNAL(finished(QNetworkReply*)),this,SLOT(replyDone(QNetworkReply*)));

4. Request and get weather related data

void myLockWindow::btn_getdata_clicked(const QString &)
{
    //获得需要查询天气的城市名称

    QString local_city = QString(city_combx->currentText());   .trimmed()
    char quest_array[256]="http://wthrcdn.etouch.cn/weather_mini?city=";
    QNetworkRequest quest;
    sprintf(quest_array,"%s%s",quest_array,local_city.toUtf8().data());
    quest.setUrl(QUrl(quest_array));
    quest.setHeader(QNetworkRequest::UserAgentHeader,"RT-Thread ART");
    //发送get网络请求
    manager->get(quest);


}

5. Processing reply data - slot function

void myLockWindow::replyDone(QNetworkReply *reply)
{

    QString all = reply->readAll();
    //        ui->textEdit->setText(all); //将接收到的数据显示出来
    qDebug()<<"recv weather data!!"<<all;
    QJsonParseError err;
    QJsonDocument json_recv = QJsonDocument::fromJson(all.toUtf8(),&err);//解析json对象
    qDebug() << err.error;
    if(!json_recv.isNull())
    {
        QJsonObject object = json_recv.object();

        if(object.contains("data"))
        {
            QJsonValue value = object.value("data");  // 获取指定 key 对应的 value
            if(value.isObject())
            {
                QJsonObject object_data = value.toObject();
                if(object_data.contains("forecast"))
                {
                    QJsonValue value = object_data.value("forecast");
                    if(value.isArray())
                    {
                        QJsonObject today_weather = value.toArray().at(0).toObject();
                        weather_type = today_weather.value("type").toString();

                        QString low = today_weather.value("low").toString();
                        QString high = today_weather.value("high").toString();
                        //                        QString ganmao = today_weather.value("ganmao").toString();//感冒提示
                        temperature= low.mid(low.length()-3,4) +"~"+ high.mid(high.length()-3,4);
                        QString strength = today_weather.value("fengli").toString();
                        strength.remove(0,8);
                        strength.remove(strength.length()-2,2);
                        wind_power= today_weather.value("fengxiang").toString() + strength;
                        this->lab_type->setText(weather_type); //显示天气类型
                        this->lab_temperature->setText(temperature);   //显示温度
                        this->lab_wind_power->setText(wind_power); //显示风力
                        //                        this->lab_ganmao->setText(ganmao);
                    }
                }
            }
        }

    }
    else
    {
        qDebug()<<"请求数据失败";
    }
    reply->deleteLater(); //销毁请求对象


}