今天来把坑填上。
具体就是提供一个URL，并通过这个URL下载文件。
MyDownloader.h： #ifndef MYDOWNLOADER_H #define MYDOWNLOADER_H
class MyDownloader :public QObject
{
Q_OBJECT
public:
//构造函数，要求下载地址，保存位置，进度条（可选）
MyDownloader();
~MyDownloader();
// 设置要下载的url和文件名
void setData(QUrl url, QString pathtoSave);
//开始下载
void getFile();
void startRequest(QUrl url);
//发生的错误代码
int lastError();
//返回是否有错误发生
bool errorValid();
//返回是否下载中
bool isRunning();
//返回是否下载完成
bool isFinished();
//返回所下载文件的版本号
QString getDownloadVersionCode();
//返回所下载文件的名字（带扩展名）
QString getFileName();
void cancel();
private:
//=====状态变量=====
bool bisFinished; //下载是否完成
bool bisRunning; //下载是否进行中
bool bisError; //是否有错误发生
int errorCode; //错误代码
int allBits = 0; //文件大小
bool httpRequestAborted;
//=====对象声明=====
QFile *downloadFile; //保存目标文件指针
QUrl downloadUrl; //下载地址Url
QString savePath; //文件存放路径
QString versionCode = ""; //所下载的文件版本号
QString fileName = ""; //所下载文件名
QNetworkReply *downloadReply; //网络应答指针
QNetworkAccessManager downloadmanager; //网络连接主类指针
signals:
//当错误发生时向外抛出错误信息
void error(QNetworkReply::NetworkError);
//抛出下载进度(更新进度条)
void updateProgress(qint64, qint64);
//下载结果 0成功 其他失败
void downloadResult(int retCode);
private slots:
//准备下载，读取数据
void downloadReadyRead();
//下载完成
void downloadFinished();
//下载过程中发生错误
void downloadError(QNetworkReply::NetworkError);
//下载过程进度条
void downloadProgress(qint64, qint64);
};
#endif// MYDOWNLOADER_H
具体实现：
MyDownloader.cpp：
MyDownloader::MyDownloader()
{
downloadFile = NULL;
downloadReply = NULL;
bisFinished = false;
}
MyDownloader::~MyDownloader()
{
cancel();
}
void MyDownloader::setData(QUrl url, QString pathtoSave)
{
downloadUrl = url;
savePath = pathtoSave;
}
void MyDownloader::getFile()
{
if (savePath.isEmpty() || downloadUrl.isEmpty())
{
return;
}
if (downloadFile)
{
return;
}
bisFinished = false;
downloadFile = new QFile(savePath);
if (!downloadFile->open(QIODevice::WriteOnly))
{
delete downloadFile;
downloadFile = 0;
return;
}
allBits = downloadFile->size();
httpRequestAborted = false;
//尝试获取文件
startRequest(downloadUrl);
//事件循环，防止在下载没完成前结束对象
}
void MyDownloader::startRequest(QUrl url)
{
QNetworkRequest req(url);
if (allBits)
{
//QByteArray rangeHeaderValue = "bytes=" + QByteArray::number(allBits) + "-";// + QByteArray::number(already + cUpdateChunk() - 1);
//req.setRawHeader("Range", rangeHeaderValue);
//req.setAttribute(QNetworkRequest::HttpPipeliningAllowedAttribute, true);
//req.setRawHeader("RANGE", tr("bytes=%1-").arg(allBits).toUtf8());//
}
downloadReply = downloadmanager.get(req);
//连接信号与槽
if (downloadReply)
{
connect(downloadReply, SIGNAL(readyRead()), this, SLOT(downloadReadyRead()));
connect(downloadReply, SIGNAL(finished()), this, SLOT(downloadFinished()));
//connect(downloadReply, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
}
}
QString MyDownloader::getDownloadVersionCode()
{
return versionCode;
}
QString MyDownloader::getFileName()
{
return fileName;
}
void MyDownloader::downloadReadyRead()
{
//如果文件可以访问，下载
if (downloadFile)
downloadFile->write(downloadReply->readAll());
}
void MyDownloader::downloadProgress(qint64 bytesRead, qint64 totalBytes)
{
}
void MyDownloader::cancel()
{
if (downloadFile)
{
downloadFile->close();
delete downloadFile;
downloadFile = NULL;
}
if (downloadReply)
{
downloadReply->deleteLater();
downloadReply = NULL;
}
}
void MyDownloader::downloadFinished()
{
if (httpRequestAborted)
{
cancel();
return;
}
downloadFile->flush();
downloadFile->close();
QVariant redirectionTarget = downloadReply->attribute(QNetworkRequest::RedirectionTargetAttribute);
if (downloadReply->error())
{//299提示RANGE错误
DEBUG_LOG(qsl("downloadReply error code:") + QString::number(downloadReply->error()));
//downloadFile->remove();
//emit downloadResult(-1);
}
else if (!redirectionTarget.isNull())
{
QUrl newUrl = downloadUrl.resolved(redirectionTarget.toUrl());
{
downloadUrl = newUrl;
downloadReply->deleteLater();
downloadFile->open(QIODevice::WriteOnly);
downloadFile->resize(0); allBits = 0;
startRequest(downloadUrl);
return;
}
}
else
{
QString fileName = QFileInfo(downloadUrl.path()).fileName();
delete downloadFile;
downloadFile = 0;
bisFinished = true;
emit downloadResult(0);
}
downloadReply->deleteLater();
downloadReply = 0;
if (downloadFile)
{
delete downloadFile;
downloadFile = 0;
}
}
void MyDownloader::downloadError(QNetworkReply::NetworkError errorcode)
{
emit downloadResult(-1);
}
bool MyDownloader::errorValid()
{
return false;
}
int MyDownloader::lastError()
{
return 0;
}
bool MyDownloader::isRunning()
{
return false;
}
bool MyDownloader::isFinished()
{
return bisFinished;
}
有些方法没有具体实现，（现在没有用到），是否有错误发生，判断是否下载中，是否下载完成，等
//////////////////////////////////////////////////////////////////////
使用：
mian.cpp void main() { MyDownloader m_downLoder; m_downLoder.setData(QUrl(m_si.custInfo.szLogoLargeUrl.c_str()), bigLogoPath); m_downLoder.cancel(); m_downLoder.getFile(); }
//////////////////////////////////////////////////////////////////////////////////////
全文完
http://blog.csdn.net/u011915578/article/details/46592963