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