/// <summary>
/// 獲取公眾號的ACCESS_TOKEN
/// </summary>
/// <returns>返回操作憑據(jù)</returns>
public string GetAccessToken()
{
　　if (HttpContext.Current.Cache["access_token"] == null)
 {
 　　string para = string.Format("grant_type=client_credential&appid={0}&secret={1}", AppID, AppSecret);
 　　string results = SendHTTPRequest("POST", "https://api.weixin.qq.com/cgi-bin/token", para);
 　　JObject obj = (JObject)JsonConvert.DeserializeObject(results);
 　　//*******************************設置access_token的過期機制**************************
 　　Cache cache = HttpContext.Current.Cache;
 　　cache.Insert("access_token", obj["access_token"].ToString(), null, DateTime.Now.AddSeconds(7000),
System.Web.Caching.Cache.NoSlidingExpiration);
　//******************************************end*************************************
 　　return HttpContext.Current.Cache["access_token"].ToString();
 }
 else
 {
 　　return HttpContext.Current.Cache["access_token"].ToString();
 }
}