用数据流处理文件-文件读取到MemoryStream中和MemoryStream写入到文件

This code writes down MemoryStream to a file:

FileStream file =newFileStream("file.bin",FileMode.Create,System.IO.FileAccess.Write);
byte[] bytes =newbyte[ms.Length];
ms.Read(bytes,0,(int)ms.Length);
file.Write(bytes,0, bytes.Length);
file.Close();
ms.Close();

and this reads a file to a MemoryStream :

MemoryStream ms =newMemoryStream();
FileStream file =newFileStream(