asp.net core webapi 文件下载实现

　　　　　　　var fileProvider = new PhysicalFileProvider("\hostpathapathb");//绝对路径，如 c:files ；网络路径：\ac

            var diretoryOptions = new DirectoryBrowserOptions
            {
                FileProvider = fileProvider,
                RequestPath = "/files",
                Formatter= new MyDirectoryFormatter(HtmlEncoder.Default)//自定义文件目录页面
            };

            var fileExtensionContentTypeProvider = new FileExtensionContentTypeProvider();
            fileExtensionContentTypeProvider.Mappings[".xml"]= "application/octet-stream"; //IE不支持           

            var fileOptions = new StaticFileOptions
            {
                FileProvider = fileProvider,
                RequestPath = "/documents",
                ContentTypeProvider = fileExtensionContentTypeProvider,
                OnPrepareResponse = (staticFileResponseContext)=>{ staticFileResponseContext.Context.Response.Headers.Add("content-disposition", "attachment"); }//在IE中让文件作为附件下载
            };

            app.UseDirectoryBrowser(diretoryOptions);
            app.UseStaticFiles();
            app.UseStaticFiles(fileOptions);