定时排程刷新微信access-token

微信公众号开发中最常遇到的就是调用接口时候需要有API的access-token（非网页授权的access-token），有了这个token之后，才可以发生模板消息等。
这里的做法主要是用nodejs的later模块是实现每隔一个小时去微信上刷新一次token，获取到最新的access-token之后保存到数据库之中。其他的业务需要用到这个token，再去数据库中抓取最新的access-token。

WechatTokenTask.js代码如下：

 var later = require('later'),
     mysql = require('mysql'),
     https = require('https'),
     moment = require('moment');

 var connection = mysql.createConnection({
     host: '112.74.***.*',
     port: 3306,
     user: 'root',
     password: '****',
     database: 'lz***'
 });

 var appid = "wx082bc0*********",
     appsecret = "d3c24a08d03b4*****************";

 // will fire every 5 minutes
 //var textSched = later.parse.text('every 1 min');
 var textSched = later.parse.cron('0 */1 * * *');
 //var textSched = later.parse.text('every 1 hours');
 //var occurrences = later.schedule(textSched).next(10);

 //for (var i = 0; i < 10; i++) {
 //    console.log(occurrences[i]);
 //}

 // execute logTime for each successive occurrence of the text schedule
 later.setInterval(dotask, textSched);

 setTimeout(dotask, 100);//fire when app start run

 function dotask() {
     var options = {
         hostname: 'api.weixin.qq.com',
         path: '/cgi-bin/token?grant_type=client_credential&appid=' + appid + '&secret=' + appsecret
     };
     var req = https.get(options, function (res) {
         //console.log("statusCode: ", res.statusCode);
         //console.log("headers: ", res.headers);
         var bodyChunks = '';
         res.on('data', function (chunk) {
             bodyChunks += chunk;
         }).on('end', function () {
             var body = JSON.parse(bodyChunks);
             //console.dir(body);
             if (body.access_token) {
                 var access_token = body.access_token;
                 saveAccessToken(access_token);
                 //console.log(access_token);
             } else {
                 console.dir(body);
             }
         })
     });

     req.on('error', function (e) {
         console.log('ERROR: ' + e.message);
     });
 }

 /* Save access token to DB*/
 function saveAccessToken(accessToken) {
     var postData = {
         AccessToken: accessToken,
         Date: moment().format('YYYY-MM-DD HH:mm:ss')
     };

     connection.connect();
     connection.query('INSERT INTO `WeChatToken` SET ?', postData, function (err, result) {
         // Neat!
         if (err) {
             console.log(JSON.stringify(err));
             connection.end();
         }

         if (result && result.affectedRows == 1) {
             console.log("success");
         }
     });
     connection.end();
 }

table scheme如下:

CREATE TABLE `WeChatToken` (
 Id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
 `Date` DATETIME NOT NULL ,
 AccessToken VARCHAR(255) NOT NULL
) ;

业务里可以用通过以下语法获取最新有效的access-token

SELECT AccessToken FROM WeChatToken ORDER BY Id DESC LIMIT 1;

该服务发布在CentOS 7, 用PM2管理。

pm2 start lzone6/WechatTokenTask.js -i 1 --name GetTokenService