Java实现微信小程序开发小程序支付开发小程序退款功能-即速应用

最近，经历多个微信小程序支付以及小程序退款实战项目，今天编者经过整理，把小程序申请退款的实战项目案例分享给大家，希望能让大家借鉴，在项目开发中少走弯路。

小程序处理退款前提需安装商户安全证书：

退款请求需要在请求服务器安装微信提供的安全证书，因为微信退款需要携带证书的请求,此证书可在申请微信商户号成功后从微信商户平台自行下载。

具体步骤详见：https://pay.weixin.qq.com/wiki/doc/api/wxa/wxa_api.php?chapter=4_3

下面详细讲解一下微信小程序（支付）退款的具体步骤

　　一. 用户发起退款请求

　　用户在前端发起退款请求，后端接收到退款请求，将相应订单标记为申请退款，商户查看后,如果同意退款再进行相应操作，此后才进入真正的退款流程.

　　二. 商户发起退款请求

商家向微信退款接口发送请求后，得到微信退款接口的响应信息，确定退款是否完成，根据退款是否完成再去进行更新订单状态等相关业务逻辑。

　　商户同意退款后,商户端即向微信提供的退款 API 发起请求。退款请求需要将需要的参数进行签名后以XML发送到微信的退款API 。详见：https://api.mch.weixin.qq.com/secapi/pay/refund

　　退款请求需要的参数如下：

　　1.小程序 appid。

　　2.商户号 mch_id 。申请开通微信支付商户认证成功后微信发给你的邮件里有

　　3.商户订单号 out_trade_no 。退款订单在支付时生成的订单号

　　4.退款订单号 out_refund_no 。由后端生成的退款单号，需要保证唯一，因为多个同样的退款单号只会退款一次。

　　5.总金额 total_fee 。订单总金额，单位为分（切记：必须为整数）

　　6.退款金额 refund_fee 需要退款的金额,单位同样为分（切记：必须为整数）

　　7.操作员 op_user_id .与商户号相同即可

　　8.随机字符串 nonce_str 。同支付请求

　　9.签名 sign ，使用上面的所有参数进行相应处理加密生成签名。

详见签名算法：https://pay.weixin.qq.com/wiki/doc/api/wxa/wxa_api.php?chapter=4_3

下面通过具体的代码讲解：

1、小程序退款工具类（主要处理微信的退款接口需要的参数）

package com.huaqi.mi.mvc.common.utils;import org.apache.commons.codec.digest.DigestUtils;import org.dom4j.Document;import org.dom4j.Element;import org.dom4j.io.SAXReader;import java.io.*;import java.net.HttpURLConnection;import java.net.URL;import java.security.SignatureException;import java.util.*;public class PayUtil {    /**     * 签名字符串     * @param text 需要签名的字符串     * @param key 密钥     * @param input_charset 编码格式     * @return 签名结果     */    public static String sign(String text, String key, String input_charset) {        text = text + "&key="+key;        return DigestUtils.md5Hex(getContentBytes(text, input_charset));    }    /**     * @param content     * @param charset     * @return     * @throws SignatureException     * @throws UnsupportedEncodingException     */    public static byte[] getContentBytes(String content, String charset) {        if (charset == null || "".equals(charset)) {            return content.getBytes();        }        try {            return content.getBytes(charset);        } catch (UnsupportedEncodingException e) {            throw new RuntimeException("MD5签名过程中出现错误,指定的编码集不对,您目前指定的编码集是:" + charset);        }    }    /**     * 生成6位或10位随机数 param codeLength(多少位)     * @return     */    public static String createCode(int codeLength) {        String code = "";        for (int i = 0; i  codeLength; i++) {            code += (int) (Math.random() * 9);        }        return code;    }    private static boolean isValidChar(char ch) {        if ((ch = '0' && ch = '9') || (ch = 'A' && ch = 'Z') || (ch = 'a' && ch = 'z'))            return true;        if ((ch = 0x4e00 && ch = 0x7fff) || (ch = 0x8000 && ch = 0x952f))            return true;// 简体中文汉字编码        return false;    }    /**     * 除去数组中的空值和签名参数     * @param sArray 签名参数组     * @return 去掉空值与签名参数后的新签名参数组     */    public static Map paraFilter(Map String,String sArray) {        Map result = new HashMap();        if (sArray == null || sArray.size() = 0) {            return result;        }        for (String key : sArray.keySet()) {            String value = sArray.get(key);            if (value == null || value.equals("") || key.equalsIgnoreCase("sign")                    || key.equalsIgnoreCase("sign_type")) {                continue;            }            result.put(key, value);        }        return result;    }    /**     * 把数组所有元素排序，并按照“参数=参数值”的模式用“&”字符拼接成字符串     * @param params 需要排序并参与字符拼接的参数组     * @return 拼接后字符串     */    public static String createLinkString(Map String,String params) {        List String keys = new ArrayList String (params.keySet());        Collections.sort(keys);        String preStr = "";        for (int i = 0; i  keys.size(); i++) {            String key = keys.get(i);            String value = params.get(key);            if (i == keys.size() - 1) {// 拼接时，不包括最后一个&字符                preStr = preStr + key + "=" + value;            } else {                preStr = preStr + key + "=" + value + "&";            }        }        return preStr;    }    /**     *     * @param requestUrl 请求地址     * @param requestMethod 请求方法     * @param outputStr 参数     */    public static String httpRequest(String requestUrl,String requestMethod,String outputStr){        // 创建SSLContext        StringBuffer buffer=null;        try{            URL url = new URL(requestUrl);            HttpURLConnection conn = (HttpURLConnection) url.openConnection();            conn.setRequestMethod(requestMethod);            conn.setDoOutput(true);            conn.setDoInput(true);            conn.connect();            //往服务器端写内容            if(null !=outputStr){                OutputStream os=conn.getOutputStream();                os.write(outputStr.getBytes("utf-8"));                os.close();            }            // 读取服务器端返回的内容            InputStream is = conn.getInputStream();            InputStreamReader isr = new InputStreamReader(is, "utf-8");            BufferedReader br = new BufferedReader(isr);            buffer = new StringBuffer();            String line = null;            while ((line = br.readLine()) != null) {                buffer.append(line);            }        }catch(Exception e){            e.printStackTrace();        }        return buffer.toString();    }    public static String urlEncodeUTF8(String source){        String result=source;        try {            result=java.net.URLEncoder.encode(source, "UTF-8");        } catch (UnsupportedEncodingException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return result;    }    /**     * 解析xml,返回第一级元素键值对。如果第一级元素有子节点，则此节点的值是子节点的xml数据。     * @param strxml     * @return     * @throws IOException     */    public static InputStream String2Inputstream(String strxml) throws IOException {        return new ByteArrayInputStream(strxml.getBytes("UTF-8"));    }    public static Map doXMLParse(String strxml) throws Exception {        MapString, String map = new HashMapString, String();        if(null == strxml || "".equals(strxml)) {            return null;        }        InputStream in = String2Inputstream(strxml);        SAXReader read = new SAXReader();        Document doc = read.read(in);        //得到xml根元素        Element root = doc.getRootElement();        //遍历  得到根元素的所有子节点        @SuppressWarnings("unchecked")        ListElement list = root.elements();        for (Element element : list) {            //装进map            map.put(element.getName(), element.getText());        }        //关闭流        in.close();        return map;    }    public static String GetMapToXML(MapString,String param){        StringBuffer sb = new StringBuffer();        sb.append("xml");        for (Map.EntryString,String entry : param.entrySet()) {            sb.append(""+ entry.getKey() +"");            sb.append(entry.getValue());            sb.append("/"+ entry.getKey() +"");        }        sb.append("/xml");        return sb.toString();    }}

2、常量类(主要存放微信小程序的相关参数)

package com.huaqi.mi.mvc.common.utils;import com.jfinal.kit.PropKit;public class Constants {//商户号public static final String MCH_ID = "";//商户号密钥public static final String key = "";//小程序IDpublic static final String appID = "";//小程序密钥public static final String secret = "";    //小程序退款Api路径public static final String REFUND_PATH = "https://api.mch.weixin.qq.com/secapi/pay/refund";    //商户证书文件安装路径(详见 https://pay.weixin.qq.com/wiki/doc/api/wxa/wxa_api.php?chapter=4_3)public static final String CERT_PATH = PropKit.get("certPath");public static final String CODE_SUCCESS = "000";public static final String CODE_ERROR = "999";public static final String MSG_NULL = "无效的订单";public static final String MSG_01 = "签名错误";public static final String REFUND_SUCCESS = "退款成功!";}

3、商户端调用微信退款接口处理退款业务的具体实现

package com.huaqi.mi.mvc.mobile.wxapp.refund;import com.huaqi.mi.mvc.common.base.BaseController;import com.huaqi.mi.mvc.common.model.*;import com.huaqi.mi.mvc.common.utils.Constants;import com.huaqi.mi.mvc.common.utils.PayUtil;import com.huaqi.mi.mvc.common.utils.UuidUtil;import org.apache.commons.lang3.StringUtils;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.config.RequestConfig;import org.apache.http.client.methods.HttpPost;import org.apache.http.conn.ssl.SSLConnectionSocketFactory;import org.apache.http.entity.StringEntity;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.ssl.SSLContexts;import org.apache.http.util.EntityUtils;import org.apache.log4j.Logger;import javax.net.ssl.SSLContext;import javax.servlet.http.HttpServletRequest;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.security.KeyStore;import java.util.Date;import java.util.HashMap;import java.util.Map;import java.util.Random;public class RefundController extends BaseController {    private static final Logger LOGGER = Logger.getLogger(RefundController.class);    private  int socketTimeout = 10000;// 连接超时时间，默认10秒    private  int connectTimeout = 30000;// 传输超时时间，默认30秒    private  static RequestConfig requestConfig;// 请求器的配置    private  static CloseableHttpClient httpClient;// HTTP请求器    public void approvalRefuse(){        //此处为商户处理退款拒绝的相关业务,不需要调用微信的退款接口    }        public void updateRefundStatus(){        //微信退款服务成功后回调，修改相关业务表的退款状态,订单状态等    }         //具体的调用微信的退款接口    public void refund() throws Exception{        String code = Constants.CODE_SUCCESS;//状态码        String msg = Constants.REFUND_SUCCESS;//提示信息        Map String,String data = new HashMapString,String();        String  orderId = getPara("orderId");        try {            if (StringUtils.isEmpty(orderId)){                code = Constants.CODE_ERROR;                msg = Constants.MSG_NULL;            }else {                BizRoomUserecord  userecord = BizRoomUserecord.dao.getById(orderId);                if(1 == userecord.getPayType()){ //退款到账户中                    BizUser  user = BizUser.dao.getById(String.valueOf(userecord.getUserId()));                    user.setAccountMoney(user.getAccountMoney()+userecord.getMoney());                    user.update();                }else{                //退款到用户微信                BizOrder  order = BizOrder.dao.getById(orderId);                String nonce_str = getRandomStringByLength(32);                data.put("userId", String.valueOf(userecord.getUserId()));                data.put("appid", Constants.appID);                data.put("mch_id", Constants.MCH_ID);                data.put("nonce_str", nonce_str);                data.put("sign_type", "MD5");                data.put("out_trade_no", order.getOrderNum());//商户订单号                data.put("out_refund_no", UuidUtil.getUUID());//商户退款单号                Math.round(userecord.getMoney() * 100);                data.put("total_fee",String.valueOf(Math.round(userecord.getMoney() * 100)));//支付金额，微信支付提交的金额是不能带小数点的，且是以分为单位,这边需要转成字符串类型，否则后面的签名会失败                data.put("refund_fee", String.valueOf(Math.round(userecord.getMoney() * 100)));//退款总金额,订单总金额,单位为分,只能为整数//                data.put("notify_url", Constants.NOTIFY_URL_REFUND);//退款成功后的回调地址                String preStr = PayUtil.createLinkString(data); // 把数组所有元素，按照“参数=参数值”的模式用“&”字符拼接成字符串                //MD5运算生成签名，这里是第一次签名，用于调用统一下单接口                String mySign = PayUtil.sign(preStr, Constants.key, "utf-8").toUpperCase();                data.put("sign", mySign);                //拼接统一下单接口使用的xml数据，要将上一步生成的签名一起拼接进去                String xmlStr = postData(Constants.REFUND_PATH, PayUtil.GetMapToXML(data)); //支付结果通知的xml格式数据                System.out.println(xmlStr);                Map notifyMap = PayUtil.doXMLParse(xmlStr);                if ("SUCCESS".equals(notifyMap.get("return_code"))) {                    if("SUCCESS".equals(notifyMap.get("result_code"))) {                        //退款成功的操作                        String prepay_id = (String) notifyMap.get("prepay_id");//返回的预付单信息                        System.out.println(prepay_id);                        Long timeStamp = System.currentTimeMillis() / 1000;                        //拼接签名需要的参数                        String stringSignTemp = "appId=" + Constants.appID + "&nonceStr=" + nonce_str + "&package=prepay_id=" + prepay_id + "&signType=MD5&timeStamp=" + timeStamp;                        //签名算法生成签名                        String paySign = PayUtil.sign(stringSignTemp, Constants.key, "utf-8").toUpperCase();                        data.put("package", "prepay_id=" + prepay_id);                        data.put("timeStamp", String.valueOf(timeStamp));                        data.put("paySign", paySign);                    }else{                        System.out.println("退款失败:原因"+notifyMap.get("return_msg"));                        code = Constants.CODE_ERROR;                        msg = (String)notifyMap.get("return_msg");                    }                }else{                    System.out.println("退款失败:原因"+notifyMap.get("return_msg"));                    code = Constants.CODE_ERROR;                    msg = (String)notifyMap.get("return_msg");                }            }            }        }catch (Exception e) {            code = Constants.CODE_ERROR;            msg = Constants.MSG_01;            LOGGER.error(e.toString(), e);        }        Map String,Object jsonResult = new HashMapString,Object();        jsonResult.put("code",code);        jsonResult.put("msg",msg);        jsonResult.put("data",data);        renderJson(jsonResult);    }    /**     * 加载证书     *     */    private static void initCert() throws Exception {        // 证书密码，默认为商户ID        String key = Constants.MCH_ID;        // 商户证书的路径        String path = Constants.CERT_PATH;        // 指定读取证书格式为PKCS12        KeyStore keyStore = KeyStore.getInstance("PKCS12");        // 读取本机存放的PKCS12证书文件        FileInputStream instream = new FileInputStream(new File(path));        try {            // 指定PKCS12的密码(商户ID)            keyStore.load(instream, key.toCharArray());        } finally {            instream.close();        }        SSLContext sslcontext = SSLContexts.custom().loadKeyMaterial(keyStore, key.toCharArray()).build();        // 指定TLS版本        SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslcontext, new String[] { "TLSv1" }, null,SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER);        // 设置httpclient的SSLSocketFactory        httpClient = HttpClients.custom().setSSLSocketFactory(sslsf).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     * @return     */    public  String postData(String url, String xmlObj) {        // 加载证书        try {            initCert();        } catch (Exception e) {            e.printStackTrace();        }        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);        // 根据默认超时限制初始化requestConfig        requestConfig = RequestConfig.custom()                .setSocketTimeout(socketTimeout)                .setConnectTimeout(connectTimeout)                .build();        // 设置请求器的配置        httpPost.setConfig(requestConfig);        try {            HttpResponse response = null;            try {                response = httpClient.execute(httpPost);            }  catch (IOException e) {                e.printStackTrace();            }            HttpEntity entity = response.getEntity();            try {                result = EntityUtils.toString(entity, "UTF-8");            }  catch (IOException e) {                e.printStackTrace();            }        } finally {            httpPost.abort();        }        return result;    }    private  String getRandomStringByLength(int length) {        String base = "abcdefghijklmnopqrstuvwxyz0123456789";        Random random = new Random();        StringBuffer sb = new StringBuffer();        for (int i = 0; i  length; i++) {            int number = random.nextInt(base.length());            sb.append(base.charAt(number));        }        return sb.toString();    }}

以上代码完美实现了用户端发起退款请求，小程序商户收到退款请求，确认允许退款再调用微信退款API向客户退款的全流程，客户微信也会收到微信的退款消息(钱会退到微信零钱或者微信绑定的银行卡)。下面是本项目处理完退款请求的部分页面。