package com.hx.corp.util;

import com.alibaba.fastjson.JSON;
import com.hx.corp.entity.CorpPayRequest;
import com.hx.corp.entity.CorpPayResponse;
import com.hx.exception.ServiceException;
import com.hx.mp.util.*;
import com.hx.util.SimpleTool;
import com.hx.util.StringUtils;
import net.sf.json.JSONObject;
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
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.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.net.ssl.SSLContext;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.FileInputStream;
import java.security.KeyStore;
import java.util.*;


/** 企业微信支付/退款
 * @author ChenJiaHe
 */
public class WxCorpPayUtil {

    //log4j日志
    private static Logger logger = LoggerFactory.getLogger(WxCorpPayUtil.class.getName());

    // 退款接口连接
    private static final String REFUND_URL = "https://api.mch.weixin.qq.com/secapi/pay/refund";
     /**查询订单链接*/
    @SuppressWarnings("unused")
    private static final String QUERY_URL = "https://api.mch.weixin.qq.com/pay/orderquery";
    /**同意下单链接*/
    private static final String FIRST_ORDER_URL = "https://api.mch.weixin.qq.com/pay/unifiedorder";

    // 企业付款
    private static final String CORP_PAY_URL = "https://api.mch.weixin.qq.com/mmpaymkttransfers/promotion/transfers";


    /** 企业付款
     * @param corpPayRequest 请求对象
     * @param mchKey 商户号秘钥
     * @param certPath 支付证书
     * @return CorpPayResponse
     * @throws Exception
     */
    public static CorpPayResponse qdCorpPay(CorpPayRequest corpPayRequest, String mchKey, String certPath)
            throws Exception {

        CorpPayResponse corpPayResponse = new CorpPayResponse();

        SortedMap<Object, Object> parameters = new TreeMap<Object, Object>();
        parameters.put("mch_appid", corpPayRequest.getMch_appid());
        parameters.put("mchid", corpPayRequest.getMchid());
        parameters.put("partner_trade_no", corpPayRequest.getPartner_trade_no());
        //parameters.put("nonce_str", UUID.randomUUID().toString().substring(0, 30));
        parameters.put("nonce_str", corpPayRequest.getNonce_str());
        parameters.put("openid", corpPayRequest.getOpenid());
        parameters.put("check_name", corpPayRequest.getCheck_name());
        parameters.put("amount", corpPayRequest.getAmount().toString());
        parameters.put("spbill_create_ip", corpPayRequest.getSpbill_create_ip());
        parameters.put("desc", corpPayRequest.getDesc());

        corpPayRequest.setSign(WXSignUtils.createSign("UTF-8", parameters, mchKey));
        parameters.put("sign", corpPayRequest.getSign());
        String xmlInfo = HttpXmlUtils.transferXml(parameters);
        try {
            CloseableHttpResponse response = HttpUtil.Post(CORP_PAY_URL, xmlInfo, true, certPath, corpPayRequest.getMchid());
            String transfersXml = EntityUtils.toString(response.getEntity(), "utf-8");

           //Map<String, String> transferMap = HttpXmlUtils.parseRefundXml(transfersXml);

            Map<String,Object> transferMap = XMLUtil.doXMLParse(transfersXml);

            // 将 Map 转换为 实体类
            corpPayResponse = JSON.parseObject(JSON.toJSONString(transferMap),CorpPayResponse.class);
        } catch (Exception e) {
            logger.error("企业付款接口报错",e);
        }
        return corpPayResponse;
    }


    /**统一支付
     * @param request 方法获取
     * @param appId  小程序号
     * @param partner  商户号
     * @param key  秘钥
     * @param notifyUrl  回调链接
     * @param out_trade_no  订单号
     * @param body 商品描述
     * @param total_fee 支付金额
     * @param openid 用户openId
     * @param attach 附带数据包
     * @param notifyUrl 回调通知地址
     * @param trade_type 交易类型
     * @return JSON  status = "SUC"为成功
     */
    public static JSONObject unifiedPay(HttpServletRequest request,String appId,String partner,String key,String notifyUrl,String out_trade_no, String body, String total_fee, String openid,
            String attach,String trade_type) throws Exception {

        if (!SimpleTool.checkNotNull(notifyUrl)) {
            throw new ServiceException("支付功能故障！");
        }

        // 创建查询请求对象
        RequestHandler reqHandler = new RequestHandler(null, null);
        // 通信对象
        TenpayHttpClient httpClient = new TenpayHttpClient();
        // 应答对象
        ClientResponseHandler resHandler = new ClientResponseHandler();

        // -----------------------------
        // 设置请求参数
        // -----------------------------
        // reqHandler.init();
        reqHandler.setKey(key);
        reqHandler.setGateUrl(FIRST_ORDER_URL);// 请求URL

        // -----------------------------
        // 设置接口参数(sign后台自动生成)
        // -----------------------------
        reqHandler.setParameter("appid", appId); // 公众号/小程序
        reqHandler.setParameter("mch_id", partner); // 商户号
        reqHandler.setParameter("nonce_str", SimpleTool.getUUIDName().substring(0, 30));// 随机乱码
        reqHandler.setParameter("body", body);// 商品描述
        reqHandler.setParameter("out_trade_no", out_trade_no);// 商户订单号
        reqHandler.setParameter("total_fee", total_fee);// 总金额
        reqHandler.setParameter("spbill_create_ip", "8.8.8.8");// 终端IP
        reqHandler.setParameter("notify_url",notifyUrl);// 通知地址
        reqHandler.setParameter("trade_type", trade_type);// 交易类型
                                                          // JSAPI，NATIVE，APP
        reqHandler.setParameter("openid", openid);// openId
        reqHandler.setParameter("attach", attach);// 附带数据包

        // -----------------------------
        // 设置通信参数
        // -----------------------------
        // 设置请求返回的等待时间
        httpClient.setTimeOut(5);

        // 设置ca证书
        // httpClient.setCaInfo(new File(CA_PATH));

        // 设置个人(商户)证书
        // httpClient.setCertInfo(new File(CERT_PATH), CERT_PWD);

        // 设置发送类型POST
        httpClient.setMethod("POST");

        // 设置请求内容(生成sign)
        String requestUrl = reqHandler.getRequestURL();// 组拼https://www.baidu.com?a=x&b=xx

        httpClient.setReqContent(requestUrl);// https://www.baidu.com?a=x&b=xx
        String rescontent = "null";

        httpClient.setRequestHandler(reqHandler);// 把处理对象，像是参数各种东西都设置进去方便获取(quan)

        // 返回出去的对象(状态，错误原因，该操作相关信息(参数,返回值))
        JSONObject returnObj = new JSONObject();

        // 后台调用
        if (httpClient.call()) {
            System.out.println("统一下单,成功cll了::");

            // 设置结果参数
            rescontent = httpClient.getResContent();
            System.out.println("统一下单返回结果:" + rescontent);
            resHandler.setContent(rescontent);// 解析xml
            resHandler.setKey(key);

            // 获取返回参数
            String return_code = resHandler.getParameter("return_code");
            String return_msg = resHandler.getParameter("return_msg");

            // 判断签名及结果
            if (resHandler.isTenpaySign() && "SUCCESS".equals(return_code)) {
                String prepay_id = resHandler.getParameter("prepay_id");// 预支付交易会话标识
                String code_url = resHandler.getParameter("code_url");// 二维码链接

                String result_code = resHandler.getParameter("result_code");// 业务结果
                String appid = resHandler.getParameter("appid");// 公众账号ID
                String mch_id = resHandler.getParameter("mch_id");// 商户号
                String nonce_str = resHandler.getParameter("nonce_str");// 随机码
                String sign = resHandler.getParameter("sign");// 签名

                if (result_code.equals("SUCCESS")) {
                    returnObj.put("status", "suc");
                    returnObj.put("sign", sign);
                    returnObj.put("nonce_str", nonce_str);
                    returnObj.put("mch_id", mch_id);
                    returnObj.put("appid", appid);
                    returnObj.put("prepay_id", prepay_id);
                    returnObj.put("code_url", code_url);
                    returnObj.put("out_trade_no", out_trade_no);
                } else {
                    String errMsg = "[ERROR]result_code:" + resHandler.getParameter("result_code") + " err_code:"
                            + resHandler.getParameter("err_code") + "err_code_des:"
                            + resHandler.getParameter("err_code_des");

                    // 错误时，返回结果未签名，记录retcode、retmsg看失败详情。
                    returnObj.put("status", "ERROR-C");
                    returnObj.put("errMsg", errMsg);
                }
            } else {
                String errMsg = "return_code:" + return_code + "err_code:" + resHandler.getParameter("err_code")
                        + " return_msg:" + return_msg;
                // 错误时，返回结果未签名，记录retcode、retmsg看失败详情。
                returnObj.put("status", "ERROR-B");
                returnObj.put("errMsg", errMsg);
            }
        } else {
            // 有可能因为网络原因，请求已经处理，但未收到应答。
            returnObj.put("status", "ERROR-A");
            returnObj.put("errMsg", httpClient.getResponseCode() + ":" + httpClient.getErrInfo());
        }

        // 获取debug信息,建议把请求、应答内容、debug信息，通信返回码写入日志，方便定位问题
        String detail = "http res:" + httpClient.getResponseCode() + "," + httpClient.getErrInfo() + ";" + "req url:"
                + requestUrl + ";" + ";" + "req debug:" + reqHandler.getDebugInfo() + ";" + "res content:" + rescontent
                + ";" + "res debug:" + resHandler.getDebugInfo() + ";";

        returnObj.put("detail", detail);

        
        return returnObj;
    }

    /**统一支付（分账）
     * @param request 方法获取
     * @param appId  小程序号
     * @param partner  商户号
     * @param key  秘钥
     * @param notifyUrl  回调链接
     * @param out_trade_no  订单号
     * @param body 商品描述
     * @param total_fee 支付金额
     * @param openid 用户openId
     * @param attach 附带数据包
     * @param notifyUrl 回调通知地址
     * @param trade_type 交易类型
     * @param profit_sharing 是否分账：N不，Y是
     * @return JSON  status = "SUC"为成功
     */
    public static JSONObject unifiedPay(HttpServletRequest request,String appId,String partner,String key,String notifyUrl,String out_trade_no, String body, String total_fee, String openid,
                                        String attach,String trade_type,String profit_sharing) throws Exception {

        if (!SimpleTool.checkNotNull(notifyUrl)) {
            throw new ServiceException("支付功能故障！");
        }

        // 创建查询请求对象
        RequestHandler reqHandler = new RequestHandler(null, null);
        // 通信对象
        TenpayHttpClient httpClient = new TenpayHttpClient();
        // 应答对象
        ClientResponseHandler resHandler = new ClientResponseHandler();

        // -----------------------------
        // 设置请求参数
        // -----------------------------
        // reqHandler.init();
        reqHandler.setKey(key);
        reqHandler.setGateUrl(FIRST_ORDER_URL);// 请求URL

        // -----------------------------
        // 设置接口参数(sign后台自动生成)
        // -----------------------------

        reqHandler.setParameter("appid", appId); // 公众号/小程序
        reqHandler.setParameter("mch_id", partner); // 商户号
        reqHandler.setParameter("nonce_str", SimpleTool.getUUIDName().substring(0, 30));// 随机乱码
        reqHandler.setParameter("body", body);// 商品描述
        reqHandler.setParameter("out_trade_no", out_trade_no);// 商户订单号
        reqHandler.setParameter("total_fee", total_fee);// 总金额
        reqHandler.setParameter("spbill_create_ip", "8.8.8.8");// 终端IP
        reqHandler.setParameter("notify_url",notifyUrl);// 通知地址
        reqHandler.setParameter("trade_type", trade_type);// 交易类型
        //JSAPI，NATIVE，APP
        reqHandler.setParameter("openid", openid);// openId
        reqHandler.setParameter("attach", attach);// 附带数据包
        reqHandler.setParameter("profit_sharing", profit_sharing);// 附带数据包

        // -----------------------------
        // 设置通信参数
        // -----------------------------
        // 设置请求返回的等待时间
        httpClient.setTimeOut(5);

        // 设置ca证书
        // httpClient.setCaInfo(new File(CA_PATH));

        // 设置个人(商户)证书
        // httpClient.setCertInfo(new File(CERT_PATH), CERT_PWD);

        // 设置发送类型POST
        httpClient.setMethod("POST");

        // 设置请求内容(生成sign)
        String requestUrl = reqHandler.getRequestURL();// 组拼https://www.baidu.com?a=x&b=xx

        httpClient.setReqContent(requestUrl);// https://www.baidu.com?a=x&b=xx
        String rescontent = "null";

        httpClient.setRequestHandler(reqHandler);// 把处理对象，像是参数各种东西都设置进去方便获取(quan)

        // 返回出去的对象(状态，错误原因，该操作相关信息(参数,返回值))
        JSONObject returnObj = new JSONObject();

        // 后台调用
        if (httpClient.call()) {
            System.out.println("统一下单,成功cll了::");

            // 设置结果参数
            rescontent = httpClient.getResContent();
            System.out.println("统一下单返回结果:" + rescontent);
            resHandler.setContent(rescontent);// 解析xml
            resHandler.setKey(key);

            // 获取返回参数
            String return_code = resHandler.getParameter("return_code");
            String return_msg = resHandler.getParameter("return_msg");

            // 判断签名及结果
            if (resHandler.isTenpaySign() && "SUCCESS".equals(return_code)) {
                String prepay_id = resHandler.getParameter("prepay_id");// 预支付交易会话标识
                String code_url = resHandler.getParameter("code_url");// 二维码链接

                String result_code = resHandler.getParameter("result_code");// 业务结果
                String appid = resHandler.getParameter("appid");// 公众账号ID
                String mch_id = resHandler.getParameter("mch_id");// 商户号
                String nonce_str = resHandler.getParameter("nonce_str");// 随机码
                String sign = resHandler.getParameter("sign");// 签名

                if (result_code.equals("SUCCESS")) {
                    returnObj.put("status", "suc");
                    returnObj.put("sign", sign);
                    returnObj.put("nonce_str", nonce_str);
                    returnObj.put("mch_id", mch_id);
                    returnObj.put("appid", appid);
                    returnObj.put("prepay_id", prepay_id);
                    returnObj.put("code_url", code_url);
                    returnObj.put("out_trade_no", out_trade_no);
                } else {
                    String errMsg = "[ERROR]result_code:" + resHandler.getParameter("result_code") + " err_code:"
                            + resHandler.getParameter("err_code") + "err_code_des:"
                            + resHandler.getParameter("err_code_des");

                    // 错误时，返回结果未签名，记录retcode、retmsg看失败详情。
                    returnObj.put("status", "ERROR-C");
                    returnObj.put("errMsg", errMsg);
                }
            } else {
                String errMsg = "return_code:" + return_code + "err_code:" + resHandler.getParameter("err_code")
                        + " return_msg:" + return_msg;
                // 错误时，返回结果未签名，记录retcode、retmsg看失败详情。
                returnObj.put("status", "ERROR-B");
                returnObj.put("errMsg", errMsg);
            }
        } else {
            // 有可能因为网络原因，请求已经处理，但未收到应答。
            returnObj.put("status", "ERROR-A");
            returnObj.put("errMsg", httpClient.getResponseCode() + ":" + httpClient.getErrInfo());
        }

        // 获取debug信息,建议把请求、应答内容、debug信息，通信返回码写入日志，方便定位问题
        String detail = "http res:" + httpClient.getResponseCode() + "," + httpClient.getErrInfo() + ";" + "req url:"
                + requestUrl + ";" + ";" + "req debug:" + reqHandler.getDebugInfo() + ";" + "res content:" + rescontent
                + ";" + "res debug:" + resHandler.getDebugInfo() + ";";

        returnObj.put("detail", detail);


        return returnObj;
    }

    /**处理信息
     */
    public static JSONObject paymentData(JSONObject payObj,String key){
        JSONObject wxObj = new JSONObject();
        /**统一下单*/
        String payStatus = payObj.getString("status");
        if (payStatus.equals("suc")) {
            // JSONObject payObj = po.getJSONObject("inf");
            String appId = payObj.getString("appid");
            String nonceStr = payObj.getString("nonce_str");
            String prepay_id = payObj.getString("prepay_id");
            // JSAPI调用支付返回的数据
            String timeStamp = SimpleTool.getTenTime(new Date()).toString();
            String signType = "MD5";
            String packagef = "prepay_id=" + prepay_id;
            RequestHandler reqHandler = new RequestHandler(null, null);
            reqHandler.setParameter("appId", appId);
            reqHandler.setParameter("nonceStr", nonceStr);
            reqHandler.setParameter("timeStamp", timeStamp);
            reqHandler.setParameter("package", packagef);
            reqHandler.setParameter("signType", signType);
            reqHandler.setKey(key);
            String paySign = reqHandler.createSign();// 生成签名
            wxObj.put("orderNo", payObj.getString("out_trade_no"));
            wxObj.put("paySign", paySign);
            wxObj.put("appId", appId);
            wxObj.put("nonceStr", nonceStr);
            wxObj.put("package", packagef);
            wxObj.put("timeStamp", timeStamp);
        } else {
            throw new RuntimeException(payObj.toString());
        }
        return wxObj;
    }

    /**
     * 退款
     * @param appId 小程序/公众号 appId
     * @param partner 商户号
     * @param key 商户号秘钥
     * @param certPath 个人商户证书
     * @param out_trade_no 商户订单号
     * @param transaction_id 财付通订单号（微信订单号）
     * @param out_refund_no 商户退单号
     * @param total_fee 订单总额(单位:分)
     * @param refund_fee 退款金额(单位:分)
     * @return JSON status="SUCCESS"(成功) (状态，错误原因，该操作相关信息(参数,返回值))
     */
    public static JSONObject refund(String appId,String partner,String key,String certPath,String out_trade_no, String transaction_id, String out_refund_no, String total_fee,
    		String refund_fee) {
 	    try{  
             KeyStore keyStore = KeyStore.getInstance("PKCS12");
             FileInputStream instream = new FileInputStream(new File(certPath));
             try {  
                 keyStore.load(instream,partner.toCharArray());
             }finally {  
                 instream.close();  
             }  
             // Trust own CA and all self-signed certs  
             SSLContext sslcontext = SSLContexts.custom().loadKeyMaterial(keyStore,partner.toCharArray()).build();
             // Allow TLSv1 protocol only  
             SSLConnectionSocketFactory sslsf;
            sslsf = new SSLConnectionSocketFactory(
                    sslcontext, new String[] { "TLSv1" }, null,
                    SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
            CloseableHttpClient httpclient = HttpClients.custom()
                     .setSSLSocketFactory(sslsf).build();  
             HttpPost httppost = new HttpPost(REFUND_URL);
             String xml = wxPayRefundData(appId, partner, key, out_trade_no, transaction_id, out_refund_no, total_fee, refund_fee);
             try {
                 StringEntity se = new StringEntity(xml);
                 httppost.setEntity(se);  

                 CloseableHttpResponse responseEntry = httpclient.execute(httppost);
                 try {  
                     HttpEntity entity = responseEntry.getEntity();
                     if (entity != null) {

                         SAXReader saxReader = new SAXReader();
                         Document document = saxReader.read(entity.getContent());
                         Element rootElt = document.getRootElement();
                         String returnCode = rootElt.elementText("return_code");
                         JSONObject result = new JSONObject();

                         if(returnCode.equals("SUCCESS")){
                             String resultCode = rootElt.elementText("result_code");
                             if(resultCode.equals("SUCCESS")) {
                                 result.put("weixinPayUrl", rootElt.elementText("code_url"));
                                 result.put("prepayId", rootElt.elementText("prepay_id"));
                                 result.put("msg", "success");

                                 String refund_id = rootElt.elementText("refund_id");//微信退款单号
                                 String r_out_refund_no = rootElt.elementText("out_refund_no");
                                 String errMsg = "商户号" + r_out_refund_no + "的退款流水号是：" + refund_id;
                                 result.put("status", "SUCCESS");
                                 result.put("errMsg", errMsg);
                                 result.put("refund_id", refund_id);
                             }else{
                                 String errMsg = "[ERROR]result_code:" + rootElt.elementText("result_code")+
                                         " err_code:" + rootElt.elementText("err_code");

                                 //错误时，返回结果未签名，记录retcode、retmsg看失败详情。
                                 result.put("errMsg", errMsg);
                                 result.put("status","false");
                                 result.put("msg",rootElt.elementText("err_code_des"));
                             }
                         }else{  
                         	String errMsg = "[ERROR]return_code:" + rootElt.elementText("return_code");
         					
         					//错误时，返回结果未签名，记录retcode、retmsg看失败详情。
                         	result.put("errMsg", errMsg);
                         	result.put("status","false");
                         	result.put("msg",rootElt.elementText("return_msg"));
                         }  
                         return result;  
                     }  
                     EntityUtils.consume(entity);
                 }  
                 finally {  
                     responseEntry.close();  
                 }  
             }  
             finally {  
                 httpclient.close();  
             }  
             return null;  
         }catch(Exception e){  
             e.printStackTrace();  
             JSONObject result = new JSONObject();  
             result.put("status","error");  
             result.put("msg",e.getMessage());  
             return result;  
         }  
    }

    /** 封装参数数据
     * @param appId 小程序/公众号 appId
     * @param partner 商户号
     * @param key 商户号秘钥
     * @param out_trade_no 商户订单号
     * @param transaction_id 财付通订单号（微信订单号）
     * @param out_refund_no 商户退单号
     * @param total_fee 订单总额(单位:分)
     * @param refund_fee 退款金额(单位:分)
     * @return
     */
    public static String wxPayRefundData(String appId,String partner,String key,String out_trade_no, String transaction_id,String out_refund_no,String total_fee,String refund_fee) {
        StringBuffer xml = new StringBuffer();
        String data = null;
        try {
            String nonceStr = SimpleTool.getUUIDName().substring(0,30);
            xml.append("</xml>");
            SortedMap<String,String> parameters = new TreeMap<String,String>();
            parameters.put("appid",appId);
            parameters.put("mch_id",partner);
            parameters.put("nonce_str", nonceStr);
            if(!StringUtils.isEmpty(out_trade_no)) {
                parameters.put("out_trade_no", out_trade_no);
            }
            if(!StringUtils.isEmpty(transaction_id)) {
                parameters.put("transaction_id", transaction_id);
            }
            parameters.put("out_refund_no", out_refund_no);
            parameters.put("fee_type", "CNY");
            parameters.put("total_fee", total_fee);//总金额
            parameters.put("refund_fee", refund_fee);//退款金额
            parameters.put("op_user_id",partner);
            parameters.put("sign", createSign(parameters,key));
            
            data =SortedMaptoXml(parameters);
        } catch (Exception e) {
            System.err.println(e.getMessage());
            return null;
        }
        return data;
    }
    
    /**
     * 创建md5摘要,规则是:按参数名称a-z排序,遇到空值的参数不参加签名。
     */
    public static String createSign(SortedMap<String, String> packageParams, String AppKey) {
        StringBuffer sb;
        sb = new StringBuffer();
        Set es = packageParams.entrySet();
        Iterator it = es.iterator();
        while (it.hasNext()) {
            Map.Entry entry = (Map.Entry) it.next();
            String k = (String) entry.getKey();
            String v = (String) entry.getValue();
            if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
                sb.append(k + "=" + v + "&");
            }
        }
        sb.append("key=" + AppKey);
        String sign = MD5Util.MD5Encode(sb.toString(), "UTF-8").toUpperCase();
        return sign;
    }
    
    /**
     * @Author: HONGLINCHEN
     * @Description:请求值转换为xml格式 SortedMap转xml
     * @param params
     * @Date: 2017-9-7 17:18
     */
    private static String SortedMaptoXml(SortedMap<String,String> params) {
        StringBuilder sb = new StringBuilder();
        Set es = params.entrySet();
        Iterator it = es.iterator();
        sb.append("<xml>\n");
        while(it.hasNext()) {
            Map.Entry entry = (Map.Entry)it.next();
            String k = (String)entry.getKey();
            Object v = entry.getValue();
            sb.append("<"+k+">");
            sb.append(v);
            sb.append("</"+k+">\n");
        }
        sb.append("</xml>");
        return sb.toString();
    }
}