<?php
/**
 * alipay.trade.refund(统一收单交易退款接口)
 *
 * 当交易发生之后一段时间内,由于买家或者卖家的原因需要退款时,卖家可以通过退款接口将支付款退还给买家,支付宝将在收到退款请求并且验证成功之后,按照退款规则将支付款按原路退到买家帐号上。
 */
header('Content-type:text/html; Charset=utf-8');
/*** 请填写以下配置信息 ***/
$appid = 'xxxxx'; //https://open.alipay.com 账户中心->密钥管理->开放平台密钥,填写添加了电脑网站支付的应用的APPID
$tradeNo = ''; //在支付宝系统中的交易流水号。最短 16 位,最长 64 位。和out_trade_no不能同时为空
$outTradeNo = ''; //订单支付时传入的商户订单号,和支付宝交易号不能同时为空。
$signType = 'RSA2'; //签名算法类型,支持RSA2和RSA,推荐使用RSA2
$refundAmount = 0.01; ////需要退款的金额,该金额不能大于订单金额,单位为元,支持两位小数
//商户私钥,填写对应签名算法类型的私钥,如何生成密钥参考:https://docs.open.alipay.com/291/105971和https://docs.open.alipay.com/200/105310
$rsaPrivateKey='';
/*** 配置结束 ***/
$aliPay = new AlipayService();
$aliPay->setAppid($appid);
$aliPay->setRsaPrivateKey($rsaPrivateKey);
$aliPay->setTradeNo($tradeNo);
$aliPay->setOutTradeNo($outTradeNo);
$aliPay->setRefundAmount($refundAmount);
$result = $aliPay->doRefund();
$result = $result['alipay_trade_refund_response'];
if($result['code'] && $result['code']=='10000'){
 echo '<h1>退款成功</h1>';
}else{
 echo $result['msg'].' : '.$result['sub_msg'];
}

class AlipayService
{
 protected $appId;
 protected $returnUrl;
 protected $notifyUrl;
 protected $charset;
 //私钥值
 protected $rsaPrivateKey;
 protected $outTradeNo;
 protected $tradeNo;
 protected $refundAmount;

 public function __construct()
 {
 $this->charset = 'utf-8';
 }
 public function setAppid($appid)
 {
 $this->appId = $appid;
 }
 public function setRsaPrivateKey($saPrivateKey)
 {
 $this->rsaPrivateKey = $saPrivateKey;
 }
 public function setOutTradeNo($outTradeNo)
 {
 $this->outTradeNo = $outTradeNo;
 }
 public function settradeNo($tradeNo)
 {
 $this->tradeNo = $tradeNo;
 }
 public function setRefundAmount($refundAmount)
 {
 $this->refundAmount = $refundAmount;
 }

 /**
 * 退款
 * @return array
 */
 public function doRefund()
 {
 //请求参数
 $requestConfigs = array(
 'trade_no'=>$this->tradeNo,
 'out_trade_no'=>$this->outTradeNo,
 'refund_amount'=>$this->refundAmount,
 );
 $commonConfigs = array(
 //公共参数
 'app_id' => $this->appId,
 'method' => 'alipay.trade.refund', //接口名称
 'format' => 'JSON',
 'charset'=>$this->charset,
 'sign_type'=>'RSA2',
 'timestamp'=>date('Y-m-d H:i:s'),
 'version'=>'1.0',
 'biz_content'=>json_encode($requestConfigs),
 );
 $commonConfigs["sign"] = $this->generateSign($commonConfigs, $commonConfigs['sign_type']);
 $result = $this->curlPost('https://openapi.alipay.com/gateway.do?charset='.$this->charset,$commonConfigs);
 $resultArr = json_decode($result,true);
 return $resultArr;
 }

 public function generateSign($params, $signType = "RSA") {
 return $this->sign($this->getSignContent($params), $signType);
 }

 protected function sign($data, $signType = "RSA") {
 $priKey=$this->rsaPrivateKey;
 $res = "-----BEGIN RSA PRIVATE KEY-----\n" .
 wordwrap($priKey, 64, "\n", true) .
 "\n-----END RSA PRIVATE KEY-----";
 ($res) or die('您使用的私钥格式错误,请检查RSA私钥配置');
 if ("RSA2" == $signType) {
 openssl_sign($data, $sign, $res, version_compare(PHP_VERSION,'5.4.0', '<') ? SHA256 : OPENSSL_ALGO_SHA256); //OPENSSL_ALGO_SHA256是php5.4.8以上版本才支持
 } else {
 openssl_sign($data, $sign, $res);
 }
 $sign = base64_encode($sign);
 return $sign;
 }

 /**
 * 校验$value是否非空
 * if not set ,return true;
 * if is null , return true;
 **/
 protected function checkEmpty($value) {
 if (!isset($value))
 return true;
 if ($value === null)
 return true;
 if (trim($value) === "")
 return true;

 return false;
 }

 public function getSignContent($params) {
 ksort($params);
 $stringToBeSigned = "";
 $i = 0;
 foreach ($params as $k => $v) {
 if (false === $this->checkEmpty($v) && "@" != substr($v, 0, 1)) {
 // 转换成目标字符集
 $v = $this->characet($v, $this->charset);
 if ($i == 0) {
 $stringToBeSigned .= "$k" . "=" . "$v";
 } else {
 $stringToBeSigned .= "&" . "$k" . "=" . "$v";
 }
 $i++;
 }
 }

 unset ($k, $v);
 return $stringToBeSigned;
 }

 /**
 * 转换字符集编码
 * @param $data
 * @param $targetCharset
 * @return string
 */
 function characet($data, $targetCharset) {
 if (!empty($data)) {
 $fileType = $this->charset;
 if (strcasecmp($fileType, $targetCharset) != 0) {
 $data = mb_convert_encoding($data, $targetCharset, $fileType);
 //$data = iconv($fileType, $targetCharset.'//IGNORE', $data);
 }
 }
 return $data;
 }

 public function curlPost($url = '', $postData = '', $options = array())
 {
 if (is_array($postData)) {
 $postData = http_build_query($postData);
 }
 $ch = curl_init();
 curl_setopt($ch, CURLOPT_URL, $url);
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
 curl_setopt($ch, CURLOPT_POST, 1);
 curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
 curl_setopt($ch, CURLOPT_TIMEOUT, 30); //设置cURL允许执行的最长秒数
 if (!empty($options)) {
 curl_setopt_array($ch, $options);
 }
 //https请求 不验证证书和host
 curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
 curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
 $data = curl_exec($ch);
 curl_close($ch);
 return $data;
 }
}