class wxpay{

    function __construct(){
        $this->wxpay();
    }
    function wxpay(){
    }

    /**
     * 生成支付二维码
     * @param   array   $order      订单信息
     * @param   array   $payment    支付方式信息
     */
    function get_code($order){
        $parameter = array(
        ‘appid‘     =>  APPID,
        ‘mch_id‘    =>  MCHID,
        ‘nonce_str‘    => strtolower(md5(mt_rand())),
        ‘body‘        => "订单支付",
        ‘out_trade_no‘=> $order[‘order_sn‘], // 此处填写订单号
        ‘product_id‘    => $order[‘order_sn‘],   // 此处填写产品号
        ‘total_fee‘    => $order[‘order_amount‘]*100,
        ‘spbill_create_ip‘=> $_SERVER["REMOTE_ADDR"],
        ‘notify_url‘    => "http://****.com/respond_wxpay.php",
        ‘trade_type‘    => "NATIVE"
        );
    // 获取code url
    $code_url = $this->getCodeUrl($parameter,PARTNER_KEY);return $code_url;
}

    /**
     * 作用：生成签名
     */
public function getSign($Obj,$key){
    foreach ($Obj as $k => $v) {
        $Parameters[$k] = $v;
    }
    // 签名步骤一：按字典序排序参数
    ksort($Parameters);
        
    $buff = "";
    foreach ($Parameters as $k => $v) {
        $buff .= $k . "=" . $v . "&";
    }
    $String="";
    if (strlen($buff) > 0) {
        $String = substr($buff, 0, strlen($buff) - 1);
    }
    // 签名步骤二：在string后加入KEY
    $String = $String . "&key=" . $key;
    // 签名步骤三：MD5加密
    $String = md5($String);
    // 签名步骤四：所有字符转为大写
    $result_ = strtoupper($String);
    return $result_;
}

/**
 * 获取code url
 */
function getCodeUrl($parameters,$key){
    // 设置接口链接
    $url = "https://api.mch.weixin.qq.com/pay/unifiedorder";
    try {
        // 检测必填参数
        if ($parameters["out_trade_no"] == null) {
            throw new Exception("缺少统一支付接口必填参数out_trade_no！" . "<br>");
        } elseif ($parameters["body"] == null) {
            throw new Exception("缺少统一支付接口必填参数body！" . "<br>");
        } elseif ($parameters["total_fee"] == null) {
            throw new Exception("缺少统一支付接口必填参数total_fee！" . "<br>");
        } elseif ($parameters["notify_url"] == null) {
            throw new Exception("缺少统一支付接口必填参数notify_url！" . "<br>");
        } elseif ($parameters["trade_type"] == null) {
            throw new Exception("缺少统一支付接口必填参数trade_type！" . "<br>");
        }
            
        $parameters["sign"] = $this->getSign($parameters,$key);
        $xml = "<xml>";
        foreach ($parameters as $key => $val) {
            if (is_numeric($val)) {
                $xml .= "<" . $key . ">" . $val . "</" . $key . ">";
            } else {
                $xml .= "<" . $key . "><![CDATA[" . $val . "]]></" . $key . ">";
            }
        }
        $xml .= "</xml>";
    } catch (Exception $e) {
        die($e->getMessage());
    }

    $response = $this->postXmlCurl($xml, $url, 30);

    $result = json_decode(json_encode(simplexml_load_string($response, ‘SimpleXMLElement‘, LIBXML_NOCDATA)), true);
    $code_url = $result["code_url"];

    return $code_url;   
}
    /**
     * 作用：以post方式提交xml到对应的接口url
     */
    public function postXmlCurl($xml, $url, $second = 30)
    {
        // 初始化curl
        $ch = curl_init();
        // 设置超时
        curl_setopt($ch, CURLOP_TIMEOUT, $second);
        // 这里设置代理，如果有的话
        // curl_setopt($ch,CURLOPT_PROXY, ‘8.8.8.8‘);
        // curl_setopt($ch,CURLOPT_PROXYPORT, 8080);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
        // 设置header
        curl_setopt($ch, CURLOPT_HEADER, FALSE);
        // 要求结果为字符串且输出到屏幕上
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
        // post提交方式
        curl_setopt($ch, CURLOPT_POST, TRUE);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
        // 运行curl
        
        $data = curl_exec($ch);
        curl_close($ch);
        // 返回结果
        if ($data) {
            curl_close($ch);
            return $data;
        } else {
            $error = curl_errno($ch);
            echo "curl出错，错误码:$error" . "<br>";
            echo "<a href=‘http://curl.haxx.se/libcurl/c/libcurl-errors.html‘>错误原因查询</a></br>";
            curl_close($ch);
            return false;
        }
    }