写入：

  string strExt = System.IO.Path.GetExtension(fromPath);//扩展名

 var file = NP_Global.TemplatePath + model.ModelName + model.ModelExt;

System.IO.FileStream fs = new System.IO.FileStream(file, FileMode.OpenOrCreate, FileAccess.Read);
                    byte[] fileByte = new byte[fs.Length];
                    fs.Read(fileByte, 0, (int)fs.Length);

                    model.FileDataJson = Convert.ToBase64String(fileByte);//转化为字符串通过json传值，保存到数据库时转化为：Convert.FromBase64String(model.FileDataJson)

读取：

model.FileDataJson = Convert.ToBase64String(fileData);
 byte[] fileData = Convert.FromBase64String(model.FileDataJson);

  var file = NP_Global.TemplatePath + model.ModelName + model.ModelExt;

 public static void SaveModel(string file, byte[] fileData)
       {
           FileStream fs = new FileStream(file, FileMode.Create);
           BinaryWriter sw = new BinaryWriter(fs);
           //开始写入
           sw.Write(fileData);
           //清空缓冲区
           sw.Flush();
           //关闭流
           sw.Close();
           sw.Dispose();
           fs.Close();
           fs.Dispose();
       }