QNetworkReply 信号 downloadProgress-QT开发中文网

在Qt中，QNetworkReply类用于处理网络请求的响应。downloadProgress信号会在下载过程中发出，用于指示当前下载进度。

使用方法

当你发送一个网络请求并获取到 QNetworkReply 的实例后，可以连接 downloadProgress 信号，以便在下载数据时更新进度条或执行其他操作。

示例代码

以下是一个简单的示例，演示如何使用 QNetworkReply 的 downloadProgress 信号：

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

class Downloader : public QObject {
    Q_OBJECT
public:
    Downloader() {
        manager = new QNetworkAccessManager(this);
        
        // 发起GET请求
        QNetworkRequest request(QUrl("https://example.com/file.zip"));
        reply = manager->get(request);
        
        // 连接信号
        connect(reply, &QNetworkReply::downloadProgress, this, &Downloader::onDownloadProgress);
        connect(reply, &QNetworkReply::finished, this, &Downloader::onFinished);
    }

private slots:
    void onDownloadProgress(qint64 bytesReceived, qint64 bytesTotal) {
        if (bytesTotal > 0) {
            double progress = static_cast<double>(bytesReceived) / bytesTotal * 100.0;
            qDebug() << "Download progress:" << progress << "%";
        }
    }

    void onFinished() {
        if (reply->error() == QNetworkReply::NoError) {
            qDebug() << "Download finished successfully!";
            // 这里可以处理下载的数据，例如保存文件
        } else {
            qDebug() << "Error occurred:" << reply->errorString();
        }
        reply->deleteLater();
    }

private:
    QNetworkAccessManager *manager;
    QNetworkReply *reply;
};

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

    return a.exec();
}

#include "main.moc"