access_token是公众号的全局唯一票据，公众号调用各接口时都需使用access_token。正常情况下access_token有效期为7200秒，重复获取将导致上次获取的access_token失效。
公众号可以使用AppID和AppSecret调用本接口来获取access_token。AppID和AppSecret可在微信公众平台官网-开发者中心页中获得（需要已经成为开发者，且帐号没有异常状态）。注意调用所有微信接口时均需使用https协议。
一、获取access_token
/// <summary> /// 通过appID和appsecret获取Access_token /// </summary> /// <returns></returns> private static Access_token GetAccess_token() { string appid = "appid"; string secret = "appsecret"; string strUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=" + appid + "&secret=" + secret; Access_token mode = new Access_token(); HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(strUrl); req.Method = "GET"; using (WebResponse wr = req.GetResponse()) { HttpWebResponse myResponse = (HttpWebResponse)req.GetResponse(); StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.UTF8); string content = reader.ReadToEnd();//在这里对Access_token 赋值 Access_token token = new Access_token(); token = JsonHelper.ParseFromJson<Access_token>(content); mode.access_token = token.access_token; mode.expires_in = token.expires_in; } return mode; }
二、由于access_token会过期，所以获取access_token的时候要验证是否过期了
/// <summary> /// 获取Access_token值 /// </summary> /// <returns></returns> public static string IsExistAccess_Token() { string Token = string.Empty; DateTime YouXRQ; // 读取XML文件中的数据，并显示出来 ，注意文件路径 string filepath = System.Web.HttpContext.Current.Server.MapPath("XMLFile.xml"); StreamReader str = new StreamReader(filepath, System.Text.Encoding.UTF8); XmlDocument xml = new XmlDocument(); xml.Load(str); str.Close(); str.Dispose(); Token = xml.SelectSingleNode("xml").SelectSingleNode("Access_Token").InnerText; YouXRQ = Convert.ToDateTime(xml.SelectSingleNode("xml").SelectSingleNode("Access_YouXRQ").InnerText); if (DateTime.Now > YouXRQ) { DateTime _youxrq = DateTime.Now; Access_token mode = GetAccess_token(); xml.SelectSingleNode("xml").SelectSingleNode("Access_Token").InnerText = mode.access_token; _youxrq = _youxrq.AddSeconds(int.Parse(mode.expires_in)); xml.SelectSingleNode("xml").SelectSingleNode("Access_YouXRQ").InnerText = _youxrq.ToString(); xml.Save(filepath); Token = mode.access_token; } return Token; }
三、