Qt通过QNetworkAccessManager实现Http get方法文件下载

前面已经实现了Qt的网络通信，这里在网络通信的基础上加上文件下载功能。相比与之前的例子添加了QFile与QProgressBar这两个类

dialog.h

 #ifndef DIALOG_H
 #define DIALOG_H

 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 /********************HTTP上传数据******************************/
 /*************************************************************/
 /*************************************************************/
 /*************************************************************/
 class Dialog : public QDialog
 {
     Q_OBJECT

 public:
     Dialog(QWidget *parent = 0);
     ~Dialog();
 protected slots:
     void httpDownload();
     void replyFinished(QNetworkReply*reply);
     void onDownloadProgress(qint64 bytesSent,qint64 bytesTotal);
     void onReadyRead();//
     void stop();//暂停，重新下载

 private:
     QPushButton *download_Btn;
     QPushButton *stop_Btn;
     QProgressBar *progressBar;
     QFile *file;
     QFileInfo fileInfo;
     QNetworkAccessManager *accessManager;
     QNetworkRequest request;
     QNetworkReply *reply;
     QVBoxLayout *layout;
     bool httpRequestAbort; //请求停止的标志位,false表示允许请求
 };
 #endif // DIALOG_H

dialog.cpp

 #include "dialog.h"
 #include

 Dialog::Dialog(QWidget *parent)
     : QDialog(parent)
 {
     download_Btn=new QPushButton("download");
     stop_Btn=new QPushButton("stop");
     progressBar=new QProgressBar;
     progressBar->hide();

     layout=new QVBoxLayout();
     layout->addWidget(progressBar);
     layout->addWidget(download_Btn);
     layout->addWidget(stop_Btn);

     setLayout(layout);
     httpRequestAbort=false;
     connect(download_Btn,SIGNAL(clicked()),this,SLOT(httpDownload()));
      connect(stop_Btn,SIGNAL(clicked()),this,SLOT(stop()));
 }

 Dialog::~Dialog()
 {

 }
 void Dialog::httpDownload(){

     QUrl url("http://mm.newhua.com/down/Samsung_USB_Drivers_for_Mobile_Phones_1.5.9.0.zip">
 http://mm.newhua.com/down/Samsung_USB_Drivers_for_Mobile_Phones_1.5.9.0.zip");
     fileInfo= url.path();
     file=new QFile(fileInfo.fileName());
     file->open(QIODevice::WriteOnly);//只读方式打开文件
     accessManager=new QNetworkAccessManager(this);
     request.setUrl(url);
     /******************设置http的header***********************/
    // request.setHeader(QNetworkRequest::ContentTypeHeader, "multipart/form-data");
    // request.setHeader(QNetworkRequest::ContentTypeHeader, "application/octet-stream");
    // request.setRawHeader("Content-Disposition","form-data;name='doc';filename='a.txt'");
     //request.setHeader(QNetworkRequest::ContentLengthHeader,post_data.length());

     reply=accessManager->get(request);//通过发送数据，返回值保存在reply指针里.
     connect(accessManager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*)));//finish为manager自带的信号，replyFinished是自定义的
     connect(reply, SIGNAL(downloadProgress(qint64,qint64)), this, SLOT( onDownloadProgress(qint64 ,qint64 )));//download文件时进度
     connect((QObject *)reply, SIGNAL(readyRead()),this, SLOT(onReadyRead()));
     progressBar->setValue(0);
     progressBar->show();
 }
 /***************响应结束**************************/
 void Dialog::replyFinished(QNetworkReply *reply){
     //获取响应的信息，状态码为200表示正常
     QVariant status_code = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
     QByteArray bytes = reply->readAll();  //获取字节
     QString result(bytes);  //转化为字符串
     qDebug()<

     //无错误返回
     if(reply->error() == QNetworkReply::NoError)
     {
         download_Btn->setText("success");
         QByteArray bytes = reply->readAll();  //获取字节
         QString result(bytes);  //转化为字符串

         qDebug()<
     }
     else
     {
         //处理错误
          download_Btn->setText("failed");
     }

     reply->deleteLater();//要删除reply，但是不能在repyfinished里直接delete，要调用deletelater;

 }

 /***********更新进度条*************/
 void Dialog::onDownloadProgress(qint64 bytesSent, qint64 bytesTotal){
     progressBar->setMaximum(bytesTotal);
     progressBar->setValue(bytesSent);

 }

 void Dialog::onReadyRead(){

     file->write(reply->readAll());
     download_Btn->setText("downloading");
 }

 void Dialog::stop(){
     if(!httpRequestAbort)
     {
     reply->abort();//响应终止
     httpRequestAbort=true;
     stop_Btn->setText("start");
 }
     else
     {   httpDownload();
         httpRequestAbort=false;
         stop_Btn->setText("stop");
      }

 }

main.cpp

 #include
 #include "dialog.h"

 int main(int argc, char *argv[])
 {
     QApplication a(argc, argv);
     Dialog w;
     w.show();
     return a.exec();
 }