利用QDataStream將大文件轉化成二進制文件QBatyArray

用QDataStream的readRawData()函數讀取二進制的文件，文件過大時會造成程序崩潰，我們可以多次讀取文件，然後將數據塊組合成整體的QByteArray

  QByteArray total_file;
  QFile file("D:/jpeg.jpg");
  int flag=file.open(QIODevice::ReadOnly);
  QDataStream in(&file);
  QFileInfo fileInfo("D:/jpeg.jpg");
  int buffer_size=65535;
  char datRawArray[buffer_size];
  qDebug()<<"nomal"<<fileInfo.size()<<endl;
  int total_size=0;
  while(!in.atEnd()){
      in.readRawData(datRawArray, buffer_size);
      QByteArray block(datRawArray,buffer_size);
      total_file=total_file+block;
  }
qDebug()<<"read file finished,yotal size:"<<total_file.size()<<endl;