Get the server address a variety of sub-types, the following records
1、HttpContext.Current.Server.MapPath("~/File")
Returned value D: \ 3Project \ Code \ MobileService \ WebApi \ File.
Local Service: This path is where the project addresses the root directory of the disk.
Deployment Server: the deployment of the disk where the file folders;
2、System.Web.Hosting.HostingEnvironment.MapPath("/File/"）
Returns a value of D: \ 3Project \ Code \ MobileService \ WebApi \ File.
Server: C: \ inetpub \ wwwroot \ File \ micro letter picture _20180814161310.pdf
3、System.AppDomain.CurrentDomain.BaseDirectory
Returned value D: \ 3Project \ Code \ MobileService \ WebApi \ File.
Local service: D: \ 3Project \ Code \ MobileService \ WebApi \ File.
Deployment Server: the deployment of the disk where the file folders;