用QDataStream的readRawData()函式讀取二進位制的檔案，檔案過大時會造成程式崩潰，我們可以多次讀取檔案，然後將資料塊組合成整體的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;