Qt软件更新(二)

Qt软件更新(二)

本篇文章介绍的是上一篇提到的下载功能，通过http URL 地址下载文件
用法原理：
1、使用QNetworkAccessManager的get方法，得到QNetworkReply
2、通过QNetworkReply其readAll方法，取得其中的QByteArray，即为下载的数据
3、利用QFile（QTemporaryFile）的write方法将数据写到磁盘上
实现功能：
添加下载地址到下载列表中，启动下载，依次下载文件
代码实现：
注意：如果新建工程时没有添加QtNetwork模块，那么就要手动在工程文件.pro中添加代码
QT += network
表明我们使用了网络模块。

#ifndef QDOWNLOAD_H
#define QDOWNLOAD_H

#include <QObject>
#include <QtNetwork>

class QDownload : public QObject
{
    Q_OBJECT
public:
    explicit QDownload(QObject *parent = nullptr);

    QNetworkAccessManager manager;
    QMap<QNetworkReply*,QString> currentDownloads;

    void doDownload(const QUrl &url,QString saveUrl = "");
    static QString saveFileName(const QUrl &url,QString saveRoute = "");
    bool saveToDisk(const QString &filename, QIODevice *data);
    static bool isHttpRedirect(QNetworkReply *reply);

private:

    struct downLoadStruct{
        QUrl url;//下载地址
        QString saveUrl;//保存路径
    };
    QList<downLoadStruct> downLoadQueue;

public slots:
    void downloadFinished(QNetworkReply *reply);
    void sslErrors(const QList<QSslError> &errors);
    void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
    void doDownload();

signals:
        void downloadFinished(QString downloadURL,QString saveURL);
        void downloadProgress(QString url,qint64 percent);
public slots:
};
#endif // QDOWNLOAD_H

#include "qdownload.h"

QDownload::QDownload(QObject *parent) : QObject(parent)
{
    connect(&manager, SIGNAL(finished(QNetworkReply*)),
            SLOT(downloadFinished(QNetworkReply*)));
}

void QDownload::doDownload(const QUrl &url,QString saveUrl)
{
    if(!downLoadQueue.isEmpty() || !currentDownloads.isEmpty())
    {
        downLoadStruct newDl;
        newDl.url = url;
        newDl.saveUrl = saveUrl;
        downLoadQueue.append(newDl);
        return;
    }

    QNetworkRequest request(url);

    QSslConfiguration config = QSslConfiguration::defaultConfiguration();
    config.setPeerVerifyMode(QSslSocket::VerifyNone);
    config.setProtocol(QSsl::TlsV1SslV3);
    request.setSslConfiguration(config);

    QNetworkReply *reply = manager.get(request);
    connect(reply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(downloadProgress(qint64,qint64)));

#if QT_CONFIG(ssl)
    connect(reply, SIGNAL(sslErrors(QList<QSslError>)),
            SLOT(sslErrors(QList<QSslError>)));
#endif

    currentDownloads.insert(reply,saveUrl);
}

QString QDownload::saveFileName(const QUrl &url,QString saveRoute)
{
    QString path = url.path();
    QString basename = QFileInfo(path).fileName();

    if (basename.isEmpty())
        basename = "download";

    if(saveRoute.isEmpty())
        saveRoute = QDir::currentPath();

    //如果路径不存在，则创建
    QDir* dir = new QDir();
    if(!dir->exists(saveRoute)){
        dir->mkpath(saveRoute);
    }

    basename = saveRoute + basename;

    if (QFile::exists(basename)) {
    }

    return basename;
}

bool QDownload::saveToDisk(const QString &filename, QIODevice *data)
{
    QFile file(filename);
    if (!file.open(QIODevice::WriteOnly)) {
        fprintf(stderr, "Could not open %s for writing: %s\n",
                qPrintable(filename),
                qPrintable(file.errorString()));
        return false;
    }

    file.write(data->readAll());
    file.close();

    return true;
}

bool QDownload::isHttpRedirect(QNetworkReply *reply)
{
    int statusCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
    return statusCode == 301 || statusCode == 302 || statusCode == 303
            || statusCode == 305 || statusCode == 307 || statusCode == 308;
}

void QDownload::doDownload()
{
    if(downLoadQueue.isEmpty())
        return;
    downLoadStruct newDl = downLoadQueue.first();
    downLoadQueue.removeFirst();

    QNetworkRequest request(newDl.url);

    QSslConfiguration config = QSslConfiguration::defaultConfiguration();
    config.setPeerVerifyMode(QSslSocket::VerifyNone);
    config.setProtocol(QSsl::TlsV1SslV3);
    request.setSslConfiguration(config);

    QNetworkReply *reply = manager.get(request);
    connect(reply,SIGNAL(downloadProgress(qint64,qint64)),this,SLOT(downloadProgress(qint64,qint64)));

#if QT_CONFIG(ssl)
    connect(reply, SIGNAL(sslErrors(QList<QSslError>)),
            SLOT(sslErrors(QList<QSslError>)));
#endif
}

void QDownload::sslErrors(const QList<QSslError> &sslErrors)
{
#if QT_CONFIG(ssl)
    for (const QSslError &error : sslErrors)
        fprintf(stderr, "SSL error: %s\n", qPrintable(error.errorString()));
#else
    Q_UNUSED(sslErrors);
#endif
}

void QDownload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
{
    qint64 Progress = static_cast<qint64>(static_cast<double>(bytesReceived)/static_cast<double>(bytesTotal)*100);

    emit downloadProgress(currentDownloads.begin().key()->url().toString(),Progress);
}

void QDownload::downloadFinished(QNetworkReply *reply)
{
    QUrl url = reply->url();
    if (reply->error()) {
        qDebug() <<  "Download of " << url.toString() << " failed:" << qPrintable(reply->errorString());

    } else {
        if (isHttpRedirect(reply)) {
//            fputs("Request was redirected.\n", stderr);
            qDebug() <<  "Request was redirected.\n" << stderr;
        } else {

            QString filename = saveFileName(url,currentDownloads.contains(reply) ? currentDownloads.find(reply).value() : "");
            if (saveToDisk(filename, reply)) {
                printf("Download of %s succeeded (saved to %s)\n",
                       url.toEncoded().constData(), qPrintable(filename));
                QDir d(filename);
                QTimer::singleShot(0,this,SLOT(doDownload()));
            emit downloadFinished(url.toString(),d.absolutePath());
            }
        }
    }
    currentDownloads.remove(reply);
    reply->deleteLater();
}