Java微信退款开发

一、下载证书并导入到系统

微信支付接口中，涉及资金回滚的接口会使用到商户证书，包括退款、撤销接口。商家在申请微信支付成功后，可以按照以下路径下载：微信商户平台(pay.weixin.qq.com)-->账户设置-->API安全-->证书下载。

下载的时候需要手机验证及登录密码。下载后找到apiclient_cert.p12这个证书，双击导入，导入的时候提示输入密码，这个密码就是商户ID,且必须是在自己的商户平台下载的证书。否则会出现密码错误的提示：

导入正确的提示：

二、编写代码

首先初始化退款接口中的请求参数，如微信订单号transaction_id（和商户订单号只需要知道一个）、订单金额total_fee等；其次调用MobiMessage中的RefundResData2xml方法解析成需要的类型；最后调用RefundRequest类的httpsRequest方法触发请求。

/**
 * 处理退款请求
 * @param request
 * @return
 * @throws Exception
 */
 @RequestMapping("/refund")
 @ResponseBody
 public JsonApi refund(HttpServletRequest request) throws Exception {
  //获得当前目录
  String path = request.getSession().getServletContext().getRealPath("/");
  LogUtils.trace(path);

  Date now = new Date();
  SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmmss");//可以方便地修改日期格式
  String outRefundNo = "NO" + dateFormat.format( now );

  //获得退款的传入参数
  String transactionID = "4008202001201609012791655620";
  String outTradeNo = "20160901141024";
  Integer totalFee = 1;
  Integer refundFee = totalFee;

  RefundReqData refundReqData = new RefundReqData(transactionID,outTradeNo,outRefundNo,totalFee,refundFee);

  String info = MobiMessage.RefundReqData2xml(refundReqData).replaceAll("__", "_");
  LogUtils.trace(info);

  try {
   RefundRequest refundRequest = new RefundRequest();
   String result = refundRequest.httpsRequest(WxConfigure.REFUND_API, info, path);
   LogUtils.trace(result);

   Map<String, String> getMap = MobiMessage.parseXml(new String(result.toString().getBytes(), "utf-8"));
   if("SUCCESS".equals(getMap.get("return_code")) && "SUCCESS".equals(getMap.get("return_msg"))){
    return new JsonApi();
   }else{
    //返回错误描述
    return new JsonApi(getMap.get("err_code_des"));
   }
  }catch(Exception e){
   e.printStackTrace();
   return new JsonApi();
  }
}

初始化退款接口需要的数据，隐藏了get和set方法。

public class RefundReqData {

 //每个字段具体的意思请查看API文档
 private String appid = "";
 private String mch_id = "";
 private String nonce_str = "";
 private String sign = "";
 private String transaction_id = "";
 private String out_trade_no = "";
 private String out_refund_no = "";
 private int total_fee = 0;
 private int refund_fee = 0;
 private String op_user_id = "";

 /**
  * 请求退款服务
  * @param transactionID 是微信系统为每一笔支付交易分配的订单号，通过这个订单号可以标识这笔交易，它由支付订单API支付成功时返回的数据里面获取到。建议优先使用
  * @param outTradeNo 商户系统内部的订单号,transaction_id 、out_trade_no 二选一，如果同时存在优先级：transaction_id>out_trade_no
  * @param outRefundNo 商户系统内部的退款单号，商户系统内部唯一，同一退款单号多次请求只退一笔
  * @param totalFee 订单总金额，单位为分
  * @param refundFee 退款总金额，单位为分
  */
 public RefundReqData(String transactionID,String outTradeNo,String outRefundNo,int totalFee,int refundFee){

  //微信分配的公众号ID（开通公众号之后可以获取到）
  setAppid(WxConfigure.AppId);

  //微信支付分配的商户号ID（开通公众号的微信支付功能之后可以获取到）
  setMch_id(WxConfigure.Mch_id);

  //transaction_id是微信系统为每一笔支付交易分配的订单号，通过这个订单号可以标识这笔交易，它由支付订单API支付成功时返回的数据里面获取到。
  setTransaction_id(transactionID);

  //商户系统自己生成的唯一的订单号
  setOut_trade_no(outTradeNo);

  setOut_refund_no(outRefundNo);

  setTotal_fee(totalFee);

  setRefund_fee(refundFee);

  setOp_user_id(WxConfigure.Mch_id);

  //随机字符串，不长于32 位
  setNonce_str(StringUtil.generateRandomString(16));

  //根据API给的签名规则进行签名
  SortedMap<Object, Object> parameters = new TreeMap<Object, Object>();
  parameters.put("appid", appid);
  parameters.put("mch_id", mch_id);
  parameters.put("nonce_str", nonce_str);
  parameters.put("transaction_id", transaction_id);
  parameters.put("out_trade_no", out_trade_no);
  parameters.put("out_refund_no", out_refund_no);
  parameters.put("total_fee", total_fee);
  parameters.put("refund_fee", refund_fee);
  parameters.put("op_user_id", op_user_id);

  String sign = DictionarySort.createSign(parameters);
  setSign(sign); //把签名数据设置到Sign这个属性中

 }

MobiMessage实现json数据类型和xml数据之间的转换。

public class MobiMessage {

 public static Map<String,String> xml2map(HttpServletRequest request) throws IOException, DocumentException {
  Map<String,String> map = new HashMap<String, String>();
  SAXReader reader = new SAXReader();
  InputStream inputStream = request.getInputStream();
  Document document = reader.read(inputStream);
  Element root = document.getRootElement();
  List<Element> list = root.elements();
  for(Element e:list){
   map.put(e.getName(), e.getText());
  }
  inputStream.close();
  return map;
 }

 //订单转换成xml
 public static String JsApiReqData2xml(JsApiReqData jsApiReqData){
  /*XStream xStream = new XStream();
  xStream.alias("xml",productInfo.getClass());
  return xStream.toXML(productInfo);*/
  MobiMessage.xstream.alias("xml",jsApiReqData.getClass());
  return MobiMessage.xstream.toXML(jsApiReqData);
 }

 public static String RefundReqData2xml(RefundReqData refundReqData){
  /*XStream xStream = new XStream();
  xStream.alias("xml",productInfo.getClass());
  return xStream.toXML(productInfo);*/
  MobiMessage.xstream.alias("xml",refundReqData.getClass());
  return MobiMessage.xstream.toXML(refundReqData);
 }

 public static String class2xml(Object object){

  return "";
 }
 public static Map<String, String> parseXml(String xml) throws Exception {
  Map<String, String> map = new HashMap<String, String>();
  Document document = DocumentHelper.parseText(xml);
  Element root = document.getRootElement();
  List<Element> elementList = root.elements();
  for (Element e : elementList)
   map.put(e.getName(), e.getText());
  return map;
 }

 //扩展xstream，使其支持CDATA块
 private static XStream xstream = new XStream(new XppDriver() {
  public HierarchicalStreamWriter createWriter(Writer out) {
   return new PrettyPrintWriter(out) {
    // 对所有xml节点的转换都增加CDATA标记
    boolean cdata = true;

    //@SuppressWarnings("unchecked")
    public void startNode(String name, Class clazz) {
     super.startNode(name, clazz);
    }

    protected void writeText(QuickWriter writer, String text) {
     if (cdata) {
      writer.write("<![CDATA[");
      writer.write(text);
      writer.write("]]>");
     } else {
      writer.write(text);
     }
    }
   };
  }
 });

}

RefundRequest类中initCert方法加载证书到系统中，其中证书地址如下：

public static String certLocalPath = "/WEB-INF/cert/apiclient_cert.p12";  

RefundRequest类中httpsRequest方法调用微信接口，触发请求。

/**
 * User: rizenguo
 * Date: 2014/10/29
 * Time: 14:36
 */
public class RefundRequest {

 //连接超时时间，默认10秒
 private int socketTimeout = 10000;

 //传输超时时间，默认30秒
 private int connectTimeout = 30000;

 //请求器的配置
 private RequestConfig requestConfig;

 //HTTP请求器
 private CloseableHttpClient httpClient;

 /**
  * 加载证书
  * @param path
  * @throws IOException
  * @throws KeyStoreException
  * @throws UnrecoverableKeyException
  * @throws NoSuchAlgorithmException
  * @throws KeyManagementException
  */
 private void initCert(String path) throws IOException, KeyStoreException, UnrecoverableKeyException, NoSuchAlgorithmException, KeyManagementException {
  //拼接证书的路径
  path = path + WxConfigure.certLocalPath;
  KeyStore keyStore = KeyStore.getInstance("PKCS12");

  //加载本地的证书进行https加密传输
  FileInputStream instream = new FileInputStream(new File(path));
  try {
   keyStore.load(instream, WxConfigure.Mch_id.toCharArray()); //加载证书密码，默认为商户ID
  } catch (CertificateException e) {
   e.printStackTrace();
  } catch (NoSuchAlgorithmException e) {
   e.printStackTrace();
  } finally {
   instream.close();
  }

  // Trust own CA and all self-signed certs
  SSLContext sslcontext = SSLContexts.custom()
    .loadKeyMaterial(keyStore, WxConfigure.Mch_id.toCharArray())  //加载证书密码，默认为商户ID
    .build();
  // Allow TLSv1 protocol only
  SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
    sslcontext,
    new String[]{"TLSv1"},
    null,
    SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER);

  httpClient = HttpClients.custom()
    .setSSLSocketFactory(sslsf)
    .build();

  //根据默认超时限制初始化requestConfig
  requestConfig = RequestConfig.custom().setSocketTimeout(socketTimeout).setConnectTimeout(connectTimeout).build();

 }

 /**
  * 通过Https往API post xml数据
  * @param url API地址
  * @param xmlObj 要提交的XML数据对象
  * @param path 当前目录，用于加载证书
  * @return
  * @throws IOException
  * @throws KeyStoreException
  * @throws UnrecoverableKeyException
  * @throws NoSuchAlgorithmException
  * @throws KeyManagementException
  */
 public String httpsRequest(String url, String xmlObj, String path) throws IOException, KeyStoreException, UnrecoverableKeyException, NoSuchAlgorithmException, KeyManagementException {
  //加载证书
  initCert(path);

  String result = null;

  HttpPost httpPost = new HttpPost(url);

  //得指明使用UTF-8编码，否则到API服务器XML的中文不能被成功识别
  StringEntity postEntity = new StringEntity(xmlObj, "UTF-8");
  httpPost.addHeader("Content-Type", "text/xml");
  httpPost.setEntity(postEntity);

  //设置请求器的配置
  httpPost.setConfig(requestConfig);

  try {
   HttpResponse response = httpClient.execute(httpPost);

   HttpEntity entity = response.getEntity();

   result = EntityUtils.toString(entity, "UTF-8");

  } catch (ConnectionPoolTimeoutException e) {
   LogUtils.trace("http get throw ConnectionPoolTimeoutException(wait time out)");

  } catch (ConnectTimeoutException e) {
   LogUtils.trace("http get throw ConnectTimeoutException");

  } catch (SocketTimeoutException e) {
    LogUtils.trace("http get throw SocketTimeoutException");

  } catch (Exception e) {
    LogUtils.trace("http get throw Exception");

  } finally {
   httpPost.abort();
  }

  return result;
 }
}

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