Qt之HTTP上传/下载
简述
在前面章节中我们讲述了关于Qt显示网络图片的内容,比较简单,因为图片一般都比较小,下载到本地速度比较快,所以基本不需要什么特殊处理,本节我们主要针对HTTP实现上传/下载进行详细的讲解与分享,包括:用户认证,实时获取下载大小、速度、剩余时间信息等。
首先看一下即将用到的公式:
文件剩余大小 = 文件总大小 - 文件已下载大小
平均速度 = 文件已下载大小 / 文件已下载大小所用的时间
瞬时速度 = 每秒下载的文件大小
剩余时间 = 文件剩余大小 / 瞬时速度
下面以下载为例,来实现一个文件下载管理器。
效果
QNetworkAccessManager
DownloadNetworkManager::DownloadNetworkManager(QObject *parent)
: QNetworkAccessManager(parent)
{
// 获取当前的时间戳,设置下载的临时文件名称
QDateTime dateTime = QDateTime::currentDateTime();
QString date = dateTime.toString("yyyy-MM-dd-hh-mm-ss-zzz");
m_strFileName = QString("E:/%1.tmp").arg(date);
connect(this, SIGNAL(finished(QNetworkReply *)), this, SLOT(replyFinished(QNetworkReply *)));
}
DownloadNetworkManager::~DownloadNetworkManager()
{
// 终止下载
if (m_pReply != NULL)
{
m_pReply->abort();
m_pReply->deleteLater();
}
}
// 设置URL及消息头,开始请求
void DownloadNetworkManager::execute()
{
m_url = QUrl("http://192.168.*.*/download/2.0.0.zip");
QNetworkRequest request;
request.setUrl(m_url);
request.setHeader(QNetworkRequest::ContentTypeHeader, "application/zip");
connect(this, SIGNAL(authenticationRequired(QNetworkReply *, QAuthenticator *)), this, SLOT(onAuthenticationRequest(QNetworkReply *, QAuthenticator *)));
m_pReply = get(request);
connect(m_pReply, SIGNAL(downloadProgress(qint64, qint64)), this, SIGNAL(downloadProgress(qint64, qint64)));
connect(m_pReply, SIGNAL(readyRead()), this, SLOT(readyRead()));
}
void DownloadNetworkManager::replyFinished(QNetworkReply *reply)
{
// 获取响应的信息,状态码为200表示正常
QVariant statusCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
// 无错误返回
if (reply->error() == QNetworkReply::NoError)
{
// 重命名临时文件
QFileInfo fileInfo(m_strFileName);
QFileInfo newFileInfo = fileInfo.absolutePath() + m_url.fileName();
QDir dir;
if (dir.exists(fileInfo.absolutePath()))
{
if (newFileInfo.exists())
newFileInfo.dir().remove(newFileInfo.fileName());
QFile::rename(m_strFileName, newFileInfo.absoluteFilePath());
}
}
else
{
QString strError = reply->errorString();
qDebug() << "Error:" << strError;
}
emit replyFinished(statusCode.toInt());
}
// 用户认证
void DownloadNetworkManager::onAuthenticationRequest(QNetworkReply *reply, QAuthenticator *authenticator)
{
QByteArray password;
password.append("123456");
password = QByteArray::fromBase64(password);
QString strPassword(password);
authenticator->setUser("wang");
authenticator->setPassword(strPassword);
}
// 本地写文件
void DownloadNetworkManager::readyRead()
{
QFileInfo fileInfo(m_strFileName);
QFileInfo newFileInfo = fileInfo.absolutePath() + m_url.fileName();
QString strFileName = newFileInfo.absoluteFilePath();
emit fileName(strFileName);
// 写文件-形式为追加
QFile file(m_strFileName);
if (file.open(QIODevice::Append))
file.write(m_pReply->readAll());
file.close();
}
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使用
调用download()接口开始下载,关联downloadProgress信号和槽,可以实时获取下载大小、速度、剩余时间等信息。
// 开始下载
void MainWindow::download()
{
if (m_pNetworkManager == NULL)
{
m_pNetworkManager = new DownloadNetworkManager(this);
connect(m_pNetworkManager, SIGNAL(downloadProgress(qint64, qint64)), this, SLOT(downloadProgress(qint64, qint64)), Qt::QueuedConnection);
connect(m_pNetworkManager, SIGNAL(replyFinished(int)), this, SLOT(replyFinished(int)), Qt::QueuedConnection);
connect(m_pNetworkManager, SIGNAL(fileName(QString)), m_pFileInfoLabel, SLOT(setText(QString)), Qt::QueuedConnection);
}
m_pNetworkManager->execute();
downloadTime.start();
}
// 计算下载大小、速度、剩余时间
void MainWindow::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
{
// 总时间
int nTime = downloadTime.elapsed();
// 本次下载所用时间
nTime -= m_nTime;
// 下载速度
double dBytesSpeed = (bytesReceived * 1000.0) / nTime;
double dSpeed = dBytesSpeed;
//剩余时间
qint64 leftBytes = (bytesTotal - bytesReceived);
double dLeftTime = (leftBytes * 1.0) / dBytesSpeed;
m_pSpeedInfoLabel->setText(speed(dSpeed));
m_pLeftTimeInfoLabel->setText(timeFormat(qCeil(dLeftTime)));
m_pFileSizeInfoLabel->setText(size(bytesTotal));
m_pDownloadInfoLabel->setText(size(bytesReceived));
m_pProgressBar->setMaximum(bytesTotal);
m_pProgressBar->setValue(bytesReceived);
// 获取上一次的时间
m_nTime = nTime;
}
// 下载完成
void MainWindow::replyFinished(int statusCode)
{
m_nStatusCode = statusCode;
QString strStatus = (statusCode == 200) ? QStringLiteral("下载成功") : QStringLiteral("下载失败");
m_pStatusLabel->setText(strStatus);
}
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转换
下面是一些数据的格式转换,包括:字节转KB、MB、GB,速度转KB/S、MB/S、GB/S,秒转*d *h *m *s格式。
// 字节转KB、MB、GB
QString size(qint64 bytes)
{
QString strUnit;
double dSize = bytes * 1.0;
if (dSize <= 0)
{
dSize = 0.0;
}
else if (dSize < 1024)
{
strUnit = "Bytes";
}
else if (dSize < 1024 * 1024)
{
dSize /= 1024;
strUnit = "KB";
}
else if (dSize < 1024 * 1024 * 1024)
{
dSize /= (1024 * 1024);
strUnit = "MB";
}
else
{
dSize /= (1024 * 1024 * 1024);
strUnit = "GB";
}
return QString("%1 %2").arg(QString::number(dSize, 'f', 2)).arg(strUnit);
}
// 速度转KB/S、MB/S、GB/S
QString speed(double speed)
{
QString strUnit;
if (speed <= 0)
{
speed = 0;
strUnit = "Bytes/S";
}
else if (speed < 1024)
{
strUnit = "Bytes/S";
}
else if (speed < 1024 * 1024)
{
speed /= 1024;
strUnit = "KB/S";
}
else if (speed < 1024 * 1024 * 1024)
{
speed /= (1024 * 1024);
strUnit = "MB/S";
}
else
{
speed /= (1024 * 1024 * 1024);
strUnit = "GB/S";
}
QString strSpeed = QString::number(speed, 'f', 2);
return QString("%1 %2").arg(strSpeed).arg(strUnit);
}
// 秒转*d *h *m *s
QString timeFormat(int seconds)
{
QString strValue;
QString strSpacing(" ");
if (seconds <= 0)
{
strValue = QString("%1s").arg(0);
}
else if (seconds < 60)
{
strValue = QString("%1s").arg(seconds);
}
else if (seconds < 60 * 60)
{
int nMinute = seconds / 60;
int nSecond = seconds - nMinute * 60;
strValue = QString("%1m").arg(nMinute);
if (nSecond > 0)
strValue += strSpacing + QString("%1s").arg(nSecond);
}
else if (seconds < 60 * 60 * 24)
{
int nHour = seconds / (60 * 60);
int nMinute = (seconds - nHour * 60 * 60) / 60;
int nSecond = seconds - nHour * 60 * 60 - nMinute * 60;
strValue = QString("%1h").arg(nHour);
if (nMinute > 0)
strValue += strSpacing + QString("%1m").arg(nMinute);
if (nSecond > 0)
strValue += strSpacing + QString("%1s").arg(nSecond);
}
else
{
int nDay = seconds / (60 * 60 * 24);
int nHour = (seconds - nDay * 60 * 60 * 24) / (60 * 60);
int nMinute = (seconds - nDay * 60 * 60 * 24 - nHour * 60 * 60) / 60;
int nSecond = seconds - nDay * 60 * 60 * 24 - nHour * 60 * 60 - nMinute * 60;
strValue = QString("%1d").arg(nDay);
if (nHour > 0)
strValue += strSpacing + QString("%1h").arg(nHour);
if (nMinute > 0)
strValue += strSpacing + QString("%1m").arg(nMinute);
if (nSecond > 0)
strValue += strSpacing + QString("%1s").arg(nSecond);
}
return strValue;
}
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总结
一般来说,我们下载文件到本地,需要设置一个临时文件名,这里我以时间戳为名称外加.tmp来命名,当然更严格的最好再加上随机数,这样基本就不会出现重名情况。
下载时,首先判断本地文件中是否存在与下载文件同名的文件,如果有则删除,开始下载。当下载完成时,需要对临时文件重新命名。
以上内容比较详细,介绍了如何进行用户认证,如何实时获取下载大小、速度、剩余时间等信息,后面我们会针对断点续传来进行详细讲解,敬请期待!