借呗分期还款模拟

Java代码 

/**
 * 阿里借呗计息还款规则说明实现
 *
 * @return
 */
package jdongtech.jiebaiUtils;

import java.util.Arrays;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;

import jdongtech.interestUtils.AverageCapitalPlusInterestUtils;

public class normalRepay {
    public static void main(String[] args) {
        // 需要手动填写
        double invest = 120; // 本金
        int month = 6;     // 期数
        double yearRate = 14.4 / 100; // 年利率
        int acctOffsetDay = 15;
        int accountDay = 13;     // 账单日，蚂蚁会把账单日设置成借款当日
        // 发起借款当天
        Calendar lendDay = Calendar.getInstance();
        lendDay.set(Calendar.MONTH, 4);
        lendDay.set(Calendar.DAY_OF_MONTH, 13);

        double dateRate = yearRate / 360;
        int[] daysCount = new int[month];
        int IncreaseFlag = 0;
        Calendar lendCalOffset = (Calendar) lendDay.clone();
        lendCalOffset.add(Calendar.DATE, acctOffsetDay);
        Calendar accCal = (Calendar) lendDay.clone();
        accCal.set(Calendar.DAY_OF_MONTH, accountDay);
        Calendar accCalBegin = (Calendar) accCal.clone();
        if (lendCalOffset.before(accCal)) {
        } else {
            accCalBegin.add(Calendar.MONTH, 1);
            IncreaseFlag = 1;
        }
        Calendar accCalEnd = (Calendar) accCal.clone();
        accCalEnd.add(Calendar.MONTH, month-1);

        System.out.println(lendDay.getTime() + "借款日期");
        System.out.println(accCalBegin.getTime() + "开始");
        System.out.println(accCalEnd.getTime() + "结束");
        int daysLending = RepayUtils.daysOffset(lendDay, accCalEnd);
        System.out.println("借款经历" + daysLending + "天");

        Calendar accCalPerEnd = (Calendar) accCalBegin.clone();
        for (int i = 0; i < month; i++) {
            Calendar accCalPerBeg;
            if (i == 0) {
                accCalPerBeg = (Calendar) lendDay.clone();
            } else {
                accCalPerBeg = (Calendar) accCalPerEnd.clone();
                accCalPerBeg.add(Calendar.MONTH, -1);
            }

            int daysPer = RepayUtils.daysOffset(accCalPerBeg, accCalPerEnd);
            daysCount[i] = daysPer;
            accCalPerEnd.add(Calendar.MONTH, 1);
        }
        //dateRate=0.0003;
        getPerMonthPrincipalInterestBig(invest, dateRate, month, daysCount, IncreaseFlag);
    }

    /**
     * 计算实际等额本息每月额度
     *
     * @return
     */
    public static double getPerMonthPrincipalInterestBig(double invest, double dateRate, int totalmonth, int[] daysCount,
            int IncreaseFlag) {
        IncreaseFlag = 1;
        double perMonthStandard = AverageCapitalPlusInterestUtils.getPerMonthPrincipalInterest(invest, dateRate * 360,
                totalmonth);

        double perMonthMax = perMonthStandard * 1.1;
        double[] PRperMonth = new double[totalmonth];
        double[] PperMonth = new double[totalmonth];
        double[] RperMonth = new double[totalmonth];
        double[] PLeftperMonth = new double[totalmonth];
        Map<Double, Double> lastCheckMap = new HashMap<Double, Double>();
        Map<Double, String> PLeftperMonthMap = new HashMap<Double, String>();
        Map<Double, String> PRperMonthMap = new HashMap<Double, String>();
        Map<Double, String> PperMonthMap = new HashMap<Double, String>();
        Map<Double, String> RperMonthMap = new HashMap<Double, String>();
        Map<Double, Double> sumPRMap = new HashMap<Double, Double>();
        Map<Double, Double> sumPMap = new HashMap<Double, Double>();
        Map<Double, Double> sumRMap = new HashMap<Double, Double>();

        if (IncreaseFlag == 1) {
            while (perMonthStandard < perMonthMax) {
                PRperMonth[0] = RepayUtils.num2second(perMonthStandard);
                PLeftperMonth[0] = RepayUtils.num2second(invest);
                RperMonth[0] = RepayUtils.num2secondDown(PLeftperMonth[0] * daysCount[0] * dateRate);
                PperMonth[0] = RepayUtils.num2second(PRperMonth[0] - RperMonth[0]);
                for (int j = 1; j < totalmonth; j++) {
                    PRperMonth[j] = RepayUtils.num2second(perMonthStandard);
                    PLeftperMonth[j] = RepayUtils.num2second(PLeftperMonth[j - 1] - PperMonth[j - 1]);
                    RperMonth[j] = RepayUtils.num2secondDown(PLeftperMonth[j] * dateRate * daysCount[j]);
                    PperMonth[j] = RepayUtils.num2second(PRperMonth[j] - RperMonth[j]);
                    if (j == totalmonth - 1) {
                        PperMonth[j] = RepayUtils.num2second(PLeftperMonth[j]);
                        PRperMonth[j] = RepayUtils.num2second(PperMonth[j] + RperMonth[j]);
                    }
                }
                double sumP = 0;
                double sumR = 0;
                double sumPR = 0;
                for (int i = 0; i < PLeftperMonth.length; i++) {
                    sumP = sumP + PperMonth[i];
                    sumR = sumR + RperMonth[i];
                    sumPR = sumPR + PRperMonth[i];
                }
                lastCheckMap.put(RepayUtils.num2second(perMonthStandard),
                        Math.abs(PRperMonth[totalmonth - 1] - PRperMonth[totalmonth - 2]));
                PLeftperMonthMap.put(RepayUtils.num2second(perMonthStandard), Arrays.toString(PLeftperMonth));
                PRperMonthMap.put(RepayUtils.num2second(perMonthStandard), Arrays.toString(PRperMonth));
                PperMonthMap.put(RepayUtils.num2second(perMonthStandard), Arrays.toString(PperMonth));
                RperMonthMap.put(RepayUtils.num2second(perMonthStandard), Arrays.toString(RperMonth));
                sumPRMap.put(RepayUtils.num2second(perMonthStandard), RepayUtils.num2second(sumPR));
                sumPMap.put(RepayUtils.num2second(perMonthStandard), RepayUtils.num2second(sumP));
                sumRMap.put(RepayUtils.num2second(perMonthStandard), RepayUtils.num2second(sumR));

                perMonthStandard = perMonthStandard + 0.01;
            }
        }

        Double resultKey = RepayUtils.getKeyByMinValue(lastCheckMap);

        System.out.println("等额本息每月还款额：" + resultKey);
        System.out.println("每期经历" + Arrays.toString(daysCount));
        System.out.println("每月余本金:" + PLeftperMonthMap.get(resultKey));
        System.out.println("每月还款额:" + PRperMonthMap.get(resultKey));
        System.out.println("每月还本金:" + PperMonthMap.get(resultKey));
        System.out.println("每月还利息:" + RperMonthMap.get(resultKey));
        System.out.println("总还款额:" + sumPRMap.get(resultKey));
        System.out.println("总还本金:" + sumPMap.get(resultKey));
        System.out.println("总还利息:" + sumRMap.get(resultKey));
        return resultKey;
    }

}