if hFile was created with FILE_FLAG_OVERLAPPED.
the lpOverlapped parameter must not be NULL. It must point to a valid OVERLAPPED structure.
传入的Overlapped结构中的hEvent在读取完成时就会被SetEvent。Overlapped中的Offset设置成要开始读取的偏移,也就是 SetFilePointer要设置的地址。
简短的操作它的方式是HasOverlappedIoCompleted判断是否完成和 CancelIo取消操作。
因此可以创建一个新线程的方式来读取,每隔一会儿HasOverlappedIoCompleted判断下是否已读取完即可。