自动更新微信access token

关键字：Memcache access_token 更新 存储 7200
本文介绍如何存储及更新 access token的方法。
 
一、Access Token
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可在开发模式中获得（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。
接口调用请求说明
http请求方式: GET
https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET
参数说明
参数
是否必须
说明
grant_type
是
获取access_token填写client_credential
appid
是
第三方用户唯一凭证
secret
是
第三方用户唯一凭证密钥，既appsecret
返回说明
正常情况下，微信会返回下述JSON数据包给公众号：
{"access_token":"ACCESS_TOKEN","expires_in":7200}
 
三、实现
          `id` int(1) NOT NULL,          `type` varchar(20) NOT NULL,          `expire` varchar(16) NOT NULL,          `value` varchar(600) NOT NULL,          PRIMARY KEY (`id`)        ) ENGINE=MyISAM DEFAULT CHARSET=utf8;        INSERT INTO `wx_token` (`id`, `type`, `expire`, `value`) VALUES        (1, 'access_token', '1425534992', 't3oyW9fRnOWKQHQhZXoEH-pgThhjmnCqTVpaLyUD'),        (2, 'jsapi_ticket', '', '');        */        $con = mysql_connect(MYSQLHOST.':'.MYSQLPORT, MYSQLUSER, MYSQLPASSWORD);        mysql_select_db(MYSQLDATABASE, $con);        $result = mysql_query("SELECT * FROM `wx_token` WHERE `type` = 'access_token'");        while($row = mysql_fetch_array($result))        {            $this->access_token = $row['value'];            $this->expires_time = $row['expire'];            break;        }        if (time() > ($this->expires_time + 3600)){            $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->appid."&secret=".$this->appsecret;            $res = $this->http_request($url);            $result = json_decode($res, true);            $this->access_token = $result["access_token"];            $this->expires_time = time();            mysql_query("UPDATE `wx_token` SET `expire` = '$this->expires_time', `value` = '$this->access_token' WHERE `type` = 'access_token';");        }        //2. 缓存形式        if (isset($_SERVER['HTTP_APPNAME'])){        //SAE环境，需要开通memcache            $mem = memcache_init();        }else {                                        //本地环境，需已安装memcache            $mem = new Memcache;            $mem->connect('localhost', 11211) or die ("Could not connect");        }        $this->access_token = $mem->get($this->appid);        if (!isset($this->access_token) || empty($this->access_token)){            $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->appid."&secret=".$this->appsecret;            $res = $this->http_request($url);            $result = json_decode($res, true);            $this->access_token = $result["access_token"];            $mem->set($this->appid, $this->access_token, 0, 3600);        }        //3. 本地写入        $res = file_get_contents('access_token.json');        $result = json_decode($res, true);        $this->expires_time = $result["expires_time"];        $this->access_token = $result["access_token"];        if (time() > ($this->expires_time + 3600)){            $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->appid."&secret=".$this->appsecret;            $res = $this->http_request($url);            $result = json_decode($res, true);            $this->access_token = $result["access_token"];            $this->expires_time = time();            file_put_contents('access_token.json', '{"access_token": "'.$this->access_token.'", "expires_time": '.$this->expires_time.'}');        }        //4. 实时拉取        $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->appid."&secret=".$this->appsecret;        $res = $this->http_request($url);        $result = json_decode($res, true);        $this->access_token = $result["access_token"];        $this->expires_time = time();    }