function Home_index() {
  
  date_default_timezone_set("Asia/Shanghai");
  $date = date("YmdHis");
  $appid = "";
  $mch_id = "";
  $out_trade_no = "14487658021497944120";
  $op_user_id = "";
  $out_refund_no = $date;
  $total_fee = "500";
  $refund_fee = "500";
//  $transaction_id = "4009542001201706206596667604";
  $key = "";
  $nonce_str = nonceStr();
 
  $ref = strtoupper(md5("appid=$appidmch_id=$mch_idnonce_str=$nonce_strop_user_id=$op_user_id"
          . "out_refund_no=$out_refund_noout_trade_no=$out_trade_norefund_fee=$refund_feetotal_fee=$total_fee"
          . "key=$key")); //sign加密MD5
 
  $refund = array(
  'appid' =>$appid, //應用ID，固定
  'mch_id' => $mch_id, //商戶號，固定
  'nonce_str' => $nonce_str, //隨機字符串
  'op_user_id' => $op_user_id, //操作員
  'out_refund_no' => $out_refund_no, //商戶內部唯一退款單號
  'out_trade_no' => $out_trade_no, //商戶訂單號,pay_sn碼 1.1二選一,微信生成的訂單號，在支付通知中有返回
  // 'transaction_id'=>'1',//微信訂單號 1.2二選一,商戶側傳給微信的訂單號
  'refund_fee' => $refund_fee, //退款金額
  'total_fee' => $total_fee, //總金額
  'sign' => $ref//簽名
  );
 
  $url = "https://api.mch.weixin.qq.com/secapi/pay/refund";
  ; //微信退款地址，post請求
  $xml = arrayToXml($refund);
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_HEADER, 1);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1); //證書檢查
  if ($useCert == true) {
    // 設置證書
    curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'pem');
    curl_setopt($ch, CURLOPT_SSLCERT, dirname(__FILE__) . '/WxPay/cert/apiclient_cert.pem');
    curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'pem');
    curl_setopt($ch, CURLOPT_SSLKEY, dirname(__FILE__) . '/WxPay/cert/apiclient_key.pem');
    curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'pem');
    curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/WxPay/cert/rootca.pem');
  }
  curl_setopt($ch, CURLOPT_POST, 1);
  curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
 
  $xml = curl_exec($ch);
 
 
  // 返回結果0的時候能只能表明程序是正常返回不一定說明退款成功而已
  if ($xml) {
    curl_close($ch);
    // 把xml轉化成數組
    libxml_disable_entity_loader(true);
    $xmlstring = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);
//    var_dump($xmlstring);
    $result['errNum'] = 0;
    $result['info'] = object_to_array($xmlstring);
//    var_dump($result);
    return $result;
  } else {
    $error = curl_errno($ch);
    curl_close($ch);
    // 錯誤的時候返回錯誤碼。
    $result['errNum'] = $error;
    return $result;
  }
}
 
function arrayToXml($arr) {
  $xml = "root>";
  foreach ($arr as $key => $val) {
    if (is_array($val)) {
      $xml .= "" . $key . ">" . arrayToXml($val) . "/" . $key . ">";
    } else {
      $xml .= "" . $key . ">" . $val . "/" . $key . ">";
    }
  }
  $xml .= "/root>";
  return $xml;
}

function object_to_array($obj) {
  $obj = (array) $obj;
  foreach ($obj as $k => $v) {
    if (gettype($v) == 'resource') {
      return;
    }
    if (gettype($v) == 'object' || gettype($v) == 'array') {
      $obj[$k] = (array) object_to_array($v);
    }
  }
 
 
  return $obj;
}
 
function nonceStr() {
  $chars = "abcdefghijklmnopqrstuvwxyz0123456789";
  $str = "";
  $length = 32;
  for ($i = 0; $i  $length; $i++) {
    $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
  }
  // 隨機字符串 
  return $str;
}
 
Home_index();