Url -从Qt5下载文件时获取内容长度

#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QUrl>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QNetworkAccessManager manager;
    QUrl url("https://example.com/file.txt");

    QNetworkRequest request(url);
    request.setOperation(QNetworkRequest::HeadOperation); // 发送HEAD请求

    QNetworkReply *reply = manager.head(request);
    QObject::connect(reply, &QNetworkReply::finished, [&]() {
        if (reply->error() == QNetworkReply::NoError) {
            QVariant contentLength = reply->header(QNetworkRequest::ContentLengthHeader);
            qDebug() << "Content Length:" << contentLength.toULongLong();
        } else {
            qDebug() << "Error:" << reply->errorString();
        }

        reply->deleteLater();
        a.quit();
    });

    return a.exec();
}