//StartUp.cs文件中Configure方法中添加以下代码
app.UseStaticFiles(new StaticFileOptions
            {
                FileProvider = new PhysicalFileProvider(Directory.GetCurrentDirectory()),
                ContentTypeProvider = new FileExtensionContentTypeProvider(new Dictionary<string, string>
                {
                      { ".wgt", "application/widget" }
                })
            });

IIS中配置MIME类型