QT QLabel load the network picture

1. Simple loading method:

void widget::on_pushButton_clicked(){

    QString szUrl="https://XXX9a74.jpg";

    Qurl url (szUrl);

    QNetworkAccessManager manager;

    QEventLoop loop;

    // qDebug() << "Reading picture form " << url;

    QNetworkReply *reply = manager.get(QNetworkRequest(url));

    // request and the end of the download is complete, exit the sub-cycle events

    QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));

    // event loop opener

    loop.exec();

    QByteArray jpegData = reply->readAll();

    QPixmap pixmap;

    pixmap.loadFromData(jpegData);

    ui-> label-> setPixmap (pixmap); // you display pictures in QLabel

}

2. Save the file to a local

void widget::downloadFileFromUrl(QString strUrl, QString strFilePath){

    qDebug() << strUrl << "    " << strFilePath;

    QFile file;

    file.setFileName(strFilePath);

    if(file.open(QIODevice::WriteOnly))

    {

        QByteArray byte = InitGetRequest(strUrl, "downImgFromUrl");

        file.write(byte);

        file.close();

    }

}

//get

QByteArray widget::InitGetRequest(QString url, QString obj)

{

    //循环拼接

    QString baseUrl =url;

    //构造请求

    QNetworkRequest request;

    request.setUrl(QUrl(baseUrl));

    QNetworkAccessManager *manager = new QNetworkAccessManager();

    // 发送请求

    QNetworkReply *pReplay = manager->get(request);

    //开启一个局部的事件循环，等待响应结束，退出

    QEventLoop eventLoop;

    QObject::connect(pReplay,SIGNAL(finished()), &eventLoop, SLOT(quit()));

 

    //add timeout deal

    QTimer *tmpTimer = new QTimer();

    connect(tmpTimer,SIGNAL(timeout()),&eventLoop, SLOT(quit()));

    tmpTimer->setSingleShot(true);

    tmpTimer->start(5000);

    eventLoop.exec();

    tmpTimer->stop();

 

    if (pReplay->error() == QNetworkReply::NoError)

    {

        qInfo() << QString("request %1 NoError").arg(obj);

    }

    else

    {

        qWarning()<<QString("request %1 handle errors here").arg(obj);

        QVariant statusCodeV = pReplay->attribute(QNetworkRequest::HttpStatusCodeAttribute);

        //statusCodeV是HTTP服务器的相应码，reply->error()是Qt定义的错误码，可以参考QT的文档

        qWarning()<<QString("request %1 found error ....code: %2 %3").arg(obj).arg(statusCodeV.toInt()).arg((int)pReplay->error());

        qWarning(qPrintable(pReplay->errorString()));

    }

    //获取响应信息

    QByteArray bytes = pReplay->readAll();

    return bytes;}