这个小程序有内存（或其他资源）泄漏吗？

AAA20090987 2012-08-17 09:33:01

先上代码：

#include <QtCore>  

#include <QtNetwork>  



//多线程下载的线程数  

const int PointCount = 100;  

//目标文件的地址（千千静听的下载地址，我用来做实验的）  

const QString strUrl = "http://ttplayer.qianqian.com/otherdown/alladin/ttpsetup_5713.exe";  



//用于下载文件（或文件的一部分）  

class Download : public QObject  

{  

	Q_OBJECT  

private:  

	QNetworkAccessManager m_Qnam;  

	QNetworkReply *m_Reply;  

	QFile *m_File;  



	const int m_Index;  

	qint64 m_HaveDoneBytes;  

	qint64 m_StartPoint;  

	qint64 m_EndPoint;  



public:  

	Download(int index, QObject *parent = 0);  

	void StartDownload(const QUrl &url, QFile *file,   

		qint64 startPoint=0, qint64 endPoint=-1);   

signals:  

	void DownloadFinished();  



	public slots:  

		void FinishedSlot();  

		void HttpReadyRead();  

};  



//用于管理文件的下载  

class DownloadControl : public QObject  

{  

	Q_OBJECT  

private:  

	int m_DownloadCount;  

	int m_FinishedNum;  

	int m_FileSize;  

	QUrl m_Url;  

	QFile *m_File;  

public:  

	DownloadControl(QObject *parent = 0);  

	void StartFileDownload(const QString &url, int count);  

	qint64 GetFileSize(QUrl url);  

signals:  

	void FileDownloadFinished();  

	private slots:  

		void SubPartFinished();  

};  



Download::Download(int index, QObject *parent)  

: QObject(parent), m_Index(index)  

{  

	m_HaveDoneBytes = 0;  

	m_StartPoint = 0;  

	m_EndPoint = 0;  

	m_File = NULL;  

}  



void Download::StartDownload(const QUrl &url,   

							 QFile *file,  

							 qint64 startPoint/* =0 */,  

							 qint64 endPoint/* =-1 */)  

{  

	if( NULL == file )  

		return;  



	m_HaveDoneBytes = 0;  

	m_StartPoint = startPoint;  

	m_EndPoint = endPoint;  

	m_File = file;  



	//根据HTTP协议，写入RANGE头部，说明请求文件的范围  

	QNetworkRequest qheader;  

	qheader.setUrl(url);  

	QString range;  

	range.sprintf("Bytes=%lld-%lld", m_StartPoint, m_EndPoint);  

	qheader.setRawHeader("Range", range.toAscii());  



	//开始下载  

	qDebug() << "Part " << m_Index << " start download";  

	m_Reply = m_Qnam.get(QNetworkRequest(qheader));  

	connect(m_Reply, SIGNAL(finished()),  

		this, SLOT(FinishedSlot()));  

	connect(m_Reply, SIGNAL(readyRead()),  

		this, SLOT(HttpReadyRead()));  

}  



//下载结束  

void Download::FinishedSlot()  

{  

	m_File->flush();  

	m_Reply->deleteLater();  

	m_Reply = 0;  

	m_File = 0;  

	qDebug() << "Part " << m_Index << " download finished";  

	emit DownloadFinished();  

}  



void Download::HttpReadyRead()  

{  

	if ( !m_File )  

		return;  



	//将读到的信息写入文件  

	QByteArray buffer = m_Reply->readAll();  

	m_File->seek( m_StartPoint + m_HaveDoneBytes );  

	m_File->write(buffer);  

	m_HaveDoneBytes += buffer.size();  

}  



//用阻塞的方式获取下载文件的长度  

qint64 DownloadControl::GetFileSize(QUrl url)  

{  

	QNetworkAccessManager manager;  

	qDebug() << "Getting the file size...";  

	QEventLoop loop;  

	//发出请求，获取目标地址的头部信息  

	QNetworkReply *reply = manager.head(QNetworkRequest(url));  

	QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit()), Qt::DirectConnection);  

	loop.exec();  

	QVariant var = reply->header(QNetworkRequest::ContentLengthHeader);  

	reply->deleteLater(); 

	qint64 size = var.toLongLong();  

	qDebug() << "The file size is: " << size;  

	return size;  

}  



DownloadControl::DownloadControl(QObject *parent)  

: QObject(parent)  

{  

	m_DownloadCount = 0;  

	m_FinishedNum = 0;  

	m_FileSize = 0;  

	m_File = new QFile;  

}  



void DownloadControl::StartFileDownload(const QString &url, int count)  

{  

	m_DownloadCount = count;  

	m_FinishedNum = 0;  

	m_Url = QUrl(url);  

	m_FileSize = GetFileSize(m_Url);  

	//先获得文件的名字  

	QFileInfo fileInfo(m_Url.path());  

	QString fileName = fileInfo.fileName();  

	if (fileName.isEmpty())  

		fileName = "index.html";  



	m_File->setFileName(fileName);  

	//打开文件  

	m_File->open(QIODevice::WriteOnly);  

	Download *tempDownload;  



	//将文件分成PointCount段，用异步的方式下载  

	qDebug() << "Start download file from " << strUrl;  

	for(int i=0; i<m_DownloadCount; i++)  

	{  

		//先算出每段的开头和结尾（HTTP协议所需要的信息）  

		int start = m_FileSize * i / m_DownloadCount;  

		int end = m_FileSize * (i+1) / m_DownloadCount;  

		if( i != 0 )  

			start--;  



		//分段下载该文件  

		tempDownload = new Download(i+1, this);  

		connect(tempDownload, SIGNAL(DownloadFinished()),   

			this, SLOT(SubPartFinished()));  

		connect(tempDownload, SIGNAL(DownloadFinished()),   

			tempDownload, SLOT(deleteLater()));  

		tempDownload->StartDownload(m_Url, m_File, start, end);  

	}  

}  



void DownloadControl::SubPartFinished()  

{  

	m_FinishedNum++;  

	//如果完成数等于文件段数，则说明文件下载完毕，关闭文件，发生信号  

	if( m_FinishedNum == m_DownloadCount )  

	{  

		m_File->close();  

		emit FileDownloadFinished();  

		qDebug() << "Download finished";  

	}  

}  



#include "main.moc"  



int main(int argc, char **argv)  

{  

	QCoreApplication app(argc, argv);  

	//用阻塞的方式下载文件，完成后退出  

	DownloadControl *control = new DownloadControl;  

	QEventLoop loop;  

	QObject::connect(control, SIGNAL(FileDownloadFinished()),   

		&loop, SLOT(quit()));  

	control->StartFileDownload(strUrl, PointCount);  

	loop.exec();  

	control->deleteLater();

	return 0;  

}

以上是我写的一个多线程下载的例子，本来是发表在我的博客上的，
博客地址：http://blog.csdn.net/aaa20090987/article/details/7223026

有几个问题：
1：有人评论说我下载完成后没释放资源（句柄），是这样的吗？应该怎么改正？
2：如果我的下载线程数变成100以上（const int PointCount = 100;），那么下载将无法完成，这是什么原因呢？

PS：为了保持DEMO的简单，我没有对网络中的错误进行处理。

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