java下载微信对账单并且解析入库代码

好的，下面是Java下载微信对账单并解析入库的示例代码：

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.csv.*;

public class WeChatBillParser {
    private static final String MCH_ID = "your_mch_id";
    private static final String APP_ID = "your_app_id";
    private static final String KEY = "your_key";
    private static final String URL = "https://api.mch.weixin.qq.com/pay/downloadbill";

    public static void main(String[] args) throws Exception {
        String dateString = "20210823"; // 对账单日期，格式为yyyyMMdd
        File file = downloadBill(dateString);
        List<WeChatBill> bills = parseBill(file);
        saveToDatabase(bills);
    }

    public static File downloadBill(String dateString) throws Exception {
        // 构造请求参数
        String nonceStr = String.valueOf(System.currentTimeMillis());
        String signType = "MD5";
        String sign = WeChatPayUtil.signParam(buildParams(dateString, nonceStr), KEY, signType);
        String xml = WeChatPayUtil.buildXml(buildParams(dateString, nonceStr, signType, sign));

        // 发送请求
        HttpURLConnection conn = (HttpURLConnection) new URL(URL).openConnection();
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
        conn.setDoOutput(true);
        conn.getOutputStream().write(xml.getBytes(StandardCharsets.UTF_8));
        conn.getOutputStream().flush();
        conn.getOutputStream().close();

        // 解析响应
        InputStream is = conn.getInputStream();
        byte[] buf = new byte[1024];
        int len;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while ((len = is.read(buf)) != -1) {
            bos.write(buf, 0, len);
        }
        is.close();
        File file = File.createTempFile("wechat_bill_", ".csv");
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(bos.toByteArray());
        fos.flush();
        fos.close();
        return file;
    }

    public static List<WeChatBill> parseBill(File file) throws IOException {
        List<WeChatBill> list = new ArrayList<>();
        CSVParser parser = CSVParser.parse(file, StandardCharsets.UTF_8, CSVFormat.DEFAULT.withHeader());
        for (CSVRecord record : parser) {
            WeChatBill bill = new WeChatBill();
            bill.setTradeTime(record.get("交易时间"));
            bill.setAppId(record.get("公众账号ID"));
            bill.setMchId(record.get("商户号"));
            bill.setDeviceInfo(record.get("设备号"));
            bill.setTransactionId(record.get("微信订单号"));
            bill.setOutTradeNo(record.get("商户订单号"));
            bill.setOpenId(record.get("用户标识"));
            bill.setTradeType(record.get("交易类型"));
            bill.setTradeStatus(record.get("交易状态"));
            bill.setBankType(record.get("付款银行"));
            bill.setTotalFee(record.get("订单金额"));
            bill.setFeeType(record.get("货币种类"));
            bill.setSettlementTotalFee(record.get("应结订单金额"));
            bill.setCouponFee(record.get("代金券金额"));
            bill.setCouponCount(record.get("代金券使用数量"));
            bill.setCouponBatchId(record.get("代金券批次ID"));
            bill.setCouponId(record.get("单个代金券ID"));
            bill.setRefundId(record.get("退款单号"));
            bill.setOutRefundNo(record.get("商户退款单号"));
            bill.setRefundFee(record.get("退款金额"));
            bill.setSettlementRefundFee(record.get("应结退款金额"));
            bill.setRefundType(record.get("退款类型"));
            bill.setRefundStatus(record.get("退款状态"));
            bill.setProductInfo(record.get("商品名称"));
            bill.setAttach(record.get("商户数据包"));
            bill.setFeeRate(record.get("费率"));
            bill.setCreateDate(record.get("交易创建时间"));
            bill.setPayDate(record.get("支付完成时间"));
            list.add(bill);
        }
        parser.close();
        return list;
    }

    public static void saveToDatabase(List<WeChatBill> bills) {
        // TODO: 将账单数据存储到数据库中
    }

    private static String buildParams(String dateString, String nonceStr) {
        StringBuilder sb = new StringBuilder();
        sb.append("appid=").append(APP_ID)
                .append("&bill_date=").append(dateString)
                .append("&bill_type=ALL")
                .append("&mch_id=").append(MCH_ID)
                .append("&nonce_str=").append(nonceStr)
                .append("&sign_type=MD5");
        return sb.toString();
    }

    private static String buildParams(String dateString, String nonceStr, String signType, String sign) {
        StringBuilder sb = new StringBuilder();
        sb.append("<xml>")
                .append("<appid>").append(APP_ID).append("</appid>")
                .append("<mch_id>").append(MCH_ID).append("</mch_id>")
                .append("<nonce_str>").append(nonceStr).append("</nonce_str>")
                .append("<sign>").append(sign).append("</sign>")
                .append("<sign_type>").append(signType).append("</sign_type>")
                .append("<bill_date>").append(dateString).append("</bill_date>")
                .append("<bill_type>ALL</bill_type>")
                .append("</xml>");
        return sb.toString();
    }
}

上面的代码中，WeChatBill是一个POJO类，用于存储解析后的对账单数据，WeChatPayUtil是一个工具类，用于生成签名等辅助操作。请根据自己的实际情况修改代码中的常量和TODO注释。