1、读取文件，并转换为字节流 FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read);
byte infbytes = new byte[(int)fs.Length];
fs.Read(infbytes, 0, infbytes.Length);
fs.Close();

return infbytes;
2、将字节流写入文件 FileStream fs = new FileStream("D:\inf.dlv", FileMode.Create, FileAccess.Write);
fs.Write(inf, 0, inf.Length);
fs.Close();