1. What is access_token?

access_token is the globally unique ticket of the public account. The public account needs to use access_token when calling each interface. Under normal circumstances, the access_token is valid for 7200 seconds. Repeated acquisition will cause the last access_token to become invalid. Since the number of API calls to obtain access_token is very limited, it is recommended that developers store and update access_token globally. Frequent refresh of access_token will limit API calls and affect their own business.

2. Problems to be solved

1. How to obtain access_token.

2. Since the validity period of access_token is 7200 seconds, that is, 2 hours, and repeated acquisition will cause the last access_token to become invalid, the number of api calls to obtain access_token is very limited, so it is necessary to solve how to globally store and update access_token. .

3. Ideas

1. Store access_token in the database.

2. When will the access_token be updated? Update when access_token expires, so how to determine whether access_token has expired? Use the current access_token to request the WeChat interface to obtain the custom menu. If the returned errcode is 42001, it means that the access_token has expired. At this time, obtain the access_token again.

Database design (table name SWX_Config):

4. Code:

1. Http request code (HttpRequestUtil class):

#region 請求Url，不發(fā)送數(shù)據(jù)
/// <summary>
/// 請求Url，不發(fā)送數(shù)據(jù)
/// </summary>
public static string RequestUrl(string url)
{
 return RequestUrl(url, "POST");
}
#endregion
 
#region 請求Url，不發(fā)送數(shù)據(jù)
/// <summary>
/// 請求Url，不發(fā)送數(shù)據(jù)
/// </summary>
public static string RequestUrl(string url, string method)
{
 // 設(shè)置參數(shù)
 HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
 CookieContainer cookieContainer = new CookieContainer();
 request.CookieContainer = cookieContainer;
 request.AllowAutoRedirect = true;
 request.Method = method;
 request.ContentType = "text/html";
 request.Headers.Add("charset", "utf-8");
 
 //發(fā)送請求并獲取相應(yīng)回應(yīng)數(shù)據(jù)
 HttpWebResponse response = request.GetResponse() as HttpWebResponse;
 //直到request.GetResponse()程序才開始向目標(biāo)網(wǎng)頁發(fā)送Post請求
 Stream responseStream = response.GetResponseStream();
 StreamReader sr = new StreamReader(responseStream, Encoding.UTF8);
 //返回結(jié)果網(wǎng)頁（html）代碼
 string content = sr.ReadToEnd();
 return content;
}
#endregion

2. Auxiliary method (Tools class):

namespace SWX.Utils
{
 /// <summary>
 /// 工具類
 /// </summary>
 public class Tools
 {
  #region 獲取Json字符串某節(jié)點的值
  /// <summary>
  /// 獲取Json字符串某節(jié)點的值
  /// </summary>
  public static string GetJsonValue(string jsonStr, string key)
  {
   string result = string.Empty;
   if (!string.IsNullOrEmpty(jsonStr))
   {
    key = "\"" + key.Trim(&#39;"&#39;) + "\"";
    int index = jsonStr.IndexOf(key) + key.Length + 1;
    if (index > key.Length + 1)
    {
     //先截逗號，若是最后一個，截“｝”號，取最小值
     int end = jsonStr.IndexOf(&#39;,&#39;, index);
     if (end == -1)
     {
      end = jsonStr.IndexOf(&#39;}&#39;, index);
     }
 
     result = jsonStr.Substring(index, end - index);
     result = result.Trim(new char[] { &#39;"&#39;, &#39; &#39;, &#39;\&#39;&#39; }); //過濾引號或空格
    }
   }
   return result;
  }
  #endregion
 
 }
}

3. Determine whether access_token has expired (WXApi class):

#region 驗證Token是否過期
/// <summary>
/// 驗證Token是否過期
/// </summary>
public static bool TokenExpired(string access_token)
{
 string jsonStr = HttpRequestUtil.RequestUrl(string.Format("https://api.weixin.qq.com/cgi-bin/menu/get?access_token={0}", access_token));
 if (Tools.GetJsonValue(jsonStr, "errcode") == "42001")
 {
  return true;
 }
 return false;
}
#endregion

4. Request the WeChat interface to obtain access_token (WXApi Class):

#region 獲取Token
/// <summary>
/// 獲取Token
/// </summary>
public static string GetToken(string appid, string secret)
{
 string strJson = HttpRequestUtil.RequestUrl(string.Format("https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid={0}&secret={1}", appid, secret));
 return Tools.GetJsonValue(strJson, "access_token");
}
#endregion

5. Global storage and update access_token (AdminUtil class):

#region 獲取access_token
/// <summary>
/// 獲取access_token
/// </summary>
public static string GetAccessToken(PageBase page)
{
 string access_token = string.Empty;
 
 UserInfo user = GetLoginUser(page);
 if (user != null)
 {
  if (string.IsNullOrWhiteSpace(user.access_token)) //尚未保存過access_token
  {
   access_token = WXApi.GetToken(user.AppID, user.AppSecret);
  }
  else
  {
   if (WXApi.TokenExpired(user.access_token)) //access_token過期
   {
    access_token = WXApi.GetToken(user.AppID, user.AppSecret);
   }
   else
   {
    return user.access_token;
   }
  }
 
  MSSQLHelper.ExecuteSql(string.Format("update SWX_Config set access_token=&#39;{0}&#39; where UserName=&#39;{1}&#39;", access_token, user.UserName));
 }
 
 return access_token;
}
#endregion

The above is the entire content of this article. I hope it will be helpful to everyone in the development of WeChat public platform.

For more articles related to the acquisition, storage and update of access_token in C# WeChat public platform development, please pay attention to the PHP Chinese website!