Qt使用http协议请求数据

一、添加网络模块​​QT += network​​二、添加头文件

#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QJsonParseError>
#include <QJsonObject>
#include <QTime>

三、http请求有两种方式，一种是阻塞式，另一种是通过信号与槽的方式
a、阻塞式

void MainWindow::on_pushButton_clicked()
{
    int startTime = QTime::currentTime().msec();
    //生成对应的网络请求
    QNetworkRequest request;
    request.setUrl(QUrl("https://blog..net/yang1fei2/article/details/119118974"));

    //发送Get请求
    QNetworkAccessManager manager;
    QNetworkReply *reply = manager.get(request);
    QEventLoop eventLoop;
    QObject::connect(reply, SIGNAL(finished()),&eventLoop, SLOT(quit()));
    eventLoop.exec(QEventLoop::ExcludeUserInputEvents);

    //对请求的返回异常进行处理
    if(reply->error() != QNetworkReply::NoError)
    {
        qDebug()<< reply->error();
        qDebug()<< "reply->error()";
        return;
    }

    //解析返回的Json结果
    QByteArray replyData = reply->readAll();
    qDebug()<<QString(replyData);

    qDebug()<<QTime::currentTime().msec() - startTime;
}

a、信号与槽的方式

void MainWindow::on_pushButton_2_clicked()
{
    //构建一个manager对象
    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    //manager具有异步API，当http请求完成后，会通过finished信号进行通知
    connect(manager,&QNetworkAccessManager::finished,this,
            [=](QNetworkReply *reply)
            {
                if(reply->error()!=QNetworkReply::NoError)
                {
                    //处理中的错误信息
                    qDebug()<<"reply error:"<<reply->errorString();
                }
                else
                {
                    //请求方式
                    qDebug()<<"operation:"<<reply->operation();
                    //状态码
                    qDebug()<<"status code:"<<reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
                    qDebug()<<"url:"<<reply->url();
                    //qDebug()<<"raw header:"<<reply->rawHeaderList();

                    //获取响应信息
                    const QByteArray reply_data=reply->readAll();
                    qDebug()<<"read all:"<<QString(reply_data).toUtf8();

                }
                reply->deleteLater();

            });
    //发送异步get请求
    manager->get(QNetworkRequest(QUrl("https://blog.net/yang1fei2/article/details/119118974")));


}