//封装request curl方法
public function request($url,$https=true,$method='get',$data=null){
    //1.初始化url
    $ch = curl_init($url);
    //2.设置请求参数
    //把数据以文件流形式保存，而不是直接输出
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    //支持http和https协议
    //https协议  ssl证书
    //绕过证书验证
    if($https === true){
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
    }
    //支持post请求
    if($method === 'post'){
        curl_setopt($ch, CURLOPT_POST, true);
        //发送的post数据
        curl_setopt($ch, CURLOPT_POSTFIELDS, $data);

    }
    //3.发送请求
    $content = curl_exec($ch);
    //4.关闭请求
    curl_close($ch);
    return $content;
}