.net 内存流MemoryStream生成文件

var memoryStream = new MemoryStream();

memoryStream=xxxxx;  //给内存流赋值

using System.IO.FileStream targetFileStream = new System.IO.FileStream($"{bucketDirectory}\\{fileName}", FileMode.OpenOrCreate);
memoryStream.WriteTo(targetFileStream);  //这里就把内存流转成了文件