1.場景還原

   最近專案要求上線微信支付原路退款功能，今天筆者就微信支付原路退款的流程梳理下，方便有需要的夥伴借閱

2.準備工作

①獲取微信支付的相關配置

WECHATPAY_PARTNER = "150xxxxxxx"; //商戶號
WECHATPAY_PARTNERKEY = "Yunjunxxxxxxxxxxxxxyyyyyyyy"; //商戶祕鑰

②獲取微信支付API證書

微信支付後臺管理--》API安全--》下載證書

③閱讀微信官方申請退款文件，確保請求引數完整

④將證書.p12檔案放置工程的resources下

InputStream instream = PropertiesUtil.class.getResourceAsStream("/yiwei/apiclient_cert.p12"
 
)

3.實現方案

程式碼如下：

@Override
public String doRefoundByWX(Map<String,Object> map) throws Exception {
    if (ObjectUtil.isNull(map.get("refund_money"),map.get("transaction_id"),map.get("channel"),map.get("sum_money"))) {
        throw new RequestException();
}

    String refund_money = map.get("refund_money"
 
).toString(); //退款金額
String out_trade_no = map.get("transaction_id").toString();//微信訂單號
String channel = map.get("channel").toString();
String sumMoney = map.get("sum_money").toString(); //訂單總價
String result = "";
//根據app渠道獲取微信的appid及appSecret
WxpayUtil.loadWxAppIdAndSecret(Integer.valueOf(channel));
String mch_id = WxpayUtil.WECHATPAY_PARTNER
 
;
String appid = WxpayUtil.WECHATPAY_APPID;
String partnerkey = WxpayUtil.WECHATPAY_PARTNERKEY;
String nonce_str = WeiXinUtil.CreateNoncestr();//隨機字串
String out_refund_no = WeiXinUtil.generatePayNO();//商戶退款單號
Double total_fee = 0d;
    try {
        total_fee = StringUtil.getDouble(sumMoney);
} catch (NumberFormatException e) {
        e.printStackTrace();
} catch (Exception e) {
        e.printStackTrace();
}
    //總金額以分為單位
long totalAmount = new BigDecimal(total_fee * 100d).longValue();
Double refund_fee = Double.parseDouble(refund_money);
//退款金額以分為單位
long Amount = new BigDecimal(refund_fee * 100d).longValue();
//簽名演算法
SortedMap<Object, Object> SortedMap = new TreeMap<Object, Object>();
SortedMap.put("appid", appid);
SortedMap.put("mch_id", mch_id);
SortedMap.put("nonce_str", nonce_str);
SortedMap.put("out_trade_no", out_trade_no);
SortedMap.put("out_refund_no", out_refund_no);
SortedMap.put("total_fee", String.valueOf(totalAmount));
SortedMap.put("refund_fee", String.valueOf(Amount));
String sign = WeiXinUtil.createSign("UTF-8",partnerkey,SortedMap);
//獲取最終待發送的資料
String requestXml = "<xml>" +
            "<appid>" + appid + "</appid>" +
            "<mch_id>" + mch_id + "</mch_id>" +
            "<nonce_str>" + nonce_str + "</nonce_str>" +
            "<out_trade_no>" + out_trade_no + "</out_trade_no>" +
            "<out_refund_no>" + out_refund_no + "</out_refund_no>" +
            "<total_fee>" + String.valueOf(totalAmount) + "</total_fee>" +
            "<refund_fee>" + String.valueOf(Amount) + "</refund_fee>" +
            "<sign>" + sign + "</sign>" +
            "</xml>";
//建立連線併發送資料
HashMap<String, Object> resultMap = null;
    try {
        result = WeiXinUtil.WeixinSendPost(requestXml,mch_id,channel);
//解析返回的xml
resultMap = new HashMap<String, Object>(XMLParse.parseXmlToList2(result));
}catch (Exception e){
        e.printStackTrace();
}

    //退款返回標誌碼
String return_code = resultMap.get("return_code").toString();
String result_code = resultMap.get("result_code").toString();
String msg = "";
    if(return_code.equals("SUCCESS") && result_code.equals("SUCCESS")){
       String userId = payorderMapper.getUserIdByOutTradeOrder(out_trade_no);
//減少使用者餘額
Integer updateAmount = this.accountMapper.subtractAmount(userId, refund_money);
// 生成我的錢包流水
Double remainAmount = this.accountMapper.findAmountByUserId(userId);
AccountFlow flow = AccountFlow.newBuilder().setUserId(userId).setOrderCode(out_trade_no).setBody("微信原路退款扣除金額")
                .setIsInflow("0").setTotal_amount(refund_money).setRemainAmount(remainAmount.toString()).build();
Integer insertAccountFlow = this.accountFlowMapper.insert(flow.toMap());
msg = "微信原路返款成功!";
        if(updateAmount != 1 || insertAccountFlow != 1) {
            TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();
            return JsonUtil.toJson(new ResultBean(true, "微信原路返款失敗", null));
}
    }else if(return_code.equals("SUCCESS") && result_code.equals("FAIL")){
        msg = "微信原路返款失敗!";
}else{
        msg = "微信原路返款未知錯誤!";
}
    return JsonUtil.toJson(new ResultBean(true, msg, null));
}

簽名方法：

/**
 * @Description：sign簽名
* @param characterEncoding
*            編碼格式
* @param parameters
* @param  secretKey
*            請求引數
* @return
*/
public static String createSign(String characterEncoding,String secretKey, SortedMap<Object, Object> parameters) {
   StringBuffer sb = new StringBuffer();
Set<Map.Entry<Object, Object>> es = parameters.entrySet();
Iterator<Map.Entry<Object, Object>> it = es.iterator();
   while (it.hasNext()) {
      Map.Entry<Object, Object> entry = (Map.Entry<Object, Object>) it.next();
String k = (String) entry.getKey();
Object v = entry.getValue();
      if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
         sb.append(k + "=" + v + "&");
}
   }
   sb.append("key=" + secretKey);
String sign = MD5Utils4WX.MD5Encode(sb.toString(), characterEncoding).toUpperCase();
parameters.put("sign", sign);
   return sign;
}

這裡的secretKey指的是微信商戶祕鑰

執行退款邏輯

public static String WeixinSendPost(Object xmlObj,String mch_id,String channel) throws IOException, KeyStoreException, UnrecoverableKeyException, NoSuchAlgorithmException, KeyManagementException {

   String result = "";
InputStream instream = PropertiesUtil.class.getResourceAsStream("/yiwei/apiclient_cert.p12");
   KeyStore keyStore = KeyStore.getInstance("PKCS12");
   try {
      keyStore.load(instream, mch_id.toCharArray());
} catch (CertificateException e) {
      e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
} finally {
      instream.close();
}

   SSLContext sslcontext = SSLContexts.custom().loadKeyMaterial(keyStore, mch_id.toCharArray()).build();
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslcontext, new String[] { "TLSv1" }, null, SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER);
CloseableHttpClient httpclient = HttpClients.custom().setSSLSocketFactory(sslsf).build();
   try {

      HttpPost httpPost = new HttpPost("https://api.mch.weixin.qq.com/secapi/pay/refund");
@SuppressWarnings("deprecation")
      HttpEntity xmlData = new StringEntity((String) xmlObj, "text/xml", "iso-8859-1");
httpPost.setEntity(xmlData);
System.out.println("executing request" + httpPost.getRequestLine());
CloseableHttpResponse response = httpclient.execute(httpPost);
      try {
         HttpEntity entity = response.getEntity();
result = EntityUtils.toString(entity, "UTF-8");
System.out.println(response.getStatusLine());
EntityUtils.consume(entity);
} finally {
         response.close();
}
   } finally {
      httpclient.close();
}
   //去除空格
return result.replaceAll(" ", "");
}

執行完之後再進行是否成功判斷

result = WeiXinUtil.WeixinSendPost(requestXml,mch_id,channel);
//解析返回的xml
resultMap = new HashMap<String, Object>(XMLParse.parseXmlToList2(result));

將xml字串解析map方法

public static Map parseXmlToList2(String xml) {
   Map retMap = new HashMap();
   try {
      StringReader read = new StringReader(xml);
// 建立新的輸入源SAX 解析器將使用 InputSource 物件來確定如何讀取 XML 輸入
InputSource source = new InputSource(read);
// 建立一個新的SAXBuilder
SAXBuilder sb = new SAXBuilder();
// 通過輸入源構造一個Document
Document doc =  sb.build(source);
Element root = (Element) doc.getRootElement();// 指向根節點
List<Element> es = root.getChildren();
      if (es != null && es.size() != 0) {
         for (Element element : es) {
            retMap.put(element.getName(), element.getValue());
}
      }
   } catch (Exception e) {
      e.printStackTrace();
}
   return retMap;
}  

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