成为了开发者之后微信平台会给您appid和secret，在订阅号中是没有的，所以因该申请一下服务号

有了ACCESSTOKEN才能做添加菜单，上传/下载图片等功能

private string GetToken() {
// 也可以这样写:
//return GetPage("https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=你的appid&secret=你的secret", "");
string res = ""; HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential
&appid=你的appid&secret=你的secret"); 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();
List<ACCESSTOKEN> myACCESSTOKEN = Json.JSONStringToList<ACCESSTOKEN>(content); res = myACCESSTOKEN[0].access_token;
}

return res; }
public string GetPage(string posturl, string postData) {
Stream outstream = null; Stream instream = null;
StreamReader sr = null; HttpWebResponse response = null;
HttpWebRequest request = null; Encoding encoding = Encoding.UTF8;
byte[] data = encoding.GetBytes(postData); // 准备请求...
try {
// 设置参数 request = WebRequest.Create(posturl) as HttpWebRequest;
CookieContainer cookieContainer = new CookieContainer(); request.CookieContainer = cookieContainer;
request.AllowAutoRedirect = true; request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = data.Length;
outstream = request.GetRequestStream(); outstream.Write(data, 0, data.Length);
outstream.Close(); //发送请求并获取相应回应数据
response = request.GetResponse() as HttpWebResponse; //直到request.GetResponse()程序才开始向目标网页发送Post请求
instream = response.GetResponseStream(); sr = new StreamReader(instream, encoding);
//返回结果网页（html）代码 string content = sr.ReadToEnd();
string err = string.Empty; return content;
} catch (Exception ex)
{ string err = ex.Message;
Response.Write(err); return string.Empty;
} }