php获取accesstoken的实现方法

class WeChat{
    private $_appid;
    private $_appsecret;
    private $_token;
    
    public function __construct($_appid,$_appsecret,$_token){
        $this->_appid = $_appid;
        $this->_appsecret = $_appsecret;
        $this->_token = $_token;
    }
    
    public function _request($curl,$https=true,$method=‘GET‘,$data=null){
        $ch = curl_init();//初始化
        curl_setopt($ch,CURLOPT_URL,$curl);//URL
        curl_setopt($ch,CURLOPT_HEADER,false);//
        curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
        if($https){
            curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,false);
            curl_setopt($ch,CURLOPT_SSL_VERIFYHOST,true);    
        }
        if($method == ‘POST‘){
            curl_setopt($ch,CURLOPT_POST,true);
            curl_setopt($ch,CURLOPT_POSTFIELDS,$data);    
        }
        $content = curl_exec($ch);
        curl_close($ch);
        return $content;
    }
    
    public function _getAccessToken(){
        $file = ‘./accesstoken‘;
        if(file_exists($file)){
            $content = file_get_contents($file);
            $content = json_decode($content);
            if(time() - filemtime($file)<$content->expires_in){
                return $content->access_token;
            }
        }
        $curl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->_appid."&secret=".$this->_appsecret;
        $content = $this->_request($curl);
        file_put_contents($file,$content);
        $content = json_decode($content);
        return $content->access_token;    
    }
}
$wechat = new WeChat(‘wxb7e7af838ec6bed2‘,‘d4624c36b6795d1d99dcf0547af5443d‘,‘‘);
echo $wechat->_getAccessToken();