獲取微信AccessToken,保存在內存中，過期后重新獲取

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Threading.Tasks;

namespace report.Utils
{
    public class WeChatHelper
    {
        public static string GetToken(string appId, string appSecret)
        {
            string tokenUrl = $"https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid={appId}&secret={appSecret}";
            var wc = new WebClient();
            var strReturn = wc.DownloadString(tokenUrl);
            return strReturn;
        }


        //token緩存鍵值對
        private static Dictionary<string, AccessToken> tokenCache = new Dictionary<string, AccessToken>();

        /// <summary>
        /// 獲取緩存令牌
        /// </summary>
        public static string GetAccessToken(string appid, string secret)
        {
            //token緩存
            AccessToken result = null;
            //判斷緩存是否存在鍵：appid，就將緩存中的token賦給result
            if (tokenCache.ContainsKey(appid))
            {
                result = tokenCache[appid];
            }
            //不存在則獲取token
            if (result == null)
            {
                result = JsonConvert.DeserializeObject<AccessToken>(GetToken(appid, secret));
                result.CreateTime = DateTime.Now;
                tokenCache.Add(appid, result);
            }
            //判斷是否在有效期內，過期重新獲取token    給10s延遲時間
            else if (System.DateTime.Compare(result.CreateTime.AddSeconds(result.Expires_In), System.DateTime.Now) < 10)
            {
                result = JsonConvert.DeserializeObject<AccessToken>(GetToken(appid, secret));
                result.CreateTime = DateTime.Now;
                tokenCache[appid] = result;
            }
            return result.Access_token;
        }
    }

    public class AccessToken
    {
        public string Access_token { get; set; }
        public int Expires_In { get; set; }
        public DateTime CreateTime { get; set; }
    }
}