// 注册服务
using Microsoft.AspNetCore.Http;
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
// 实现层
// 注入引用
private readonly IHttpContextAccessor _httpContextAccessor;
_httpContextAccessor = serviceProvider.GetService<IHttpContextAccessor>();
// 方法内
var headers = _httpContextAccessor.HttpContext.Request.Headers;
string str_u = headers["User-Agent"].FirstOrDefault();
// 简易判断
string[] keywords = { "Android", "iPhone", "iPod", "iPad", "Windows Phone", "MQQBrowser" };
var clientType = keywords.Where(x => str_u.IndexOf(x) > -1).Any() ? "Mobile" : "PC";