根据贷款还款方式（等额本金 等额本息 等本等息 先息后本） 计算本息

package com.alex.examples.utils.money;import lombok.Data;import java.io.Serializable;import java.math.BigDecimal;@Datapublic class MoneyVo implements Serializable {private Integer number;//期数private BigDecimal monthPrincipalInterest;//本息private BigDecimal monthPrincipal;//本金private BigDecimal monthInterest;//利息}

package com.alex.examples.utils.money;import cn.hutool.core.math.MathUtil;import java.math.BigDecimal;import java.util.ArrayList;import java.util.List;public class MoneyUtils {public static void main(String[] args) {Long principal = 1000000L; //贷款本息Double interest = 0.01; //月利息Integer months = 12; //贷款期数// //等额本金// List<MoneyVo> list = DEBJ(new BigDecimal(MathUtil.centToYuan(principal)), interest, months);// list.forEach(vo -> System.out.println("期数：" + vo.getNumber()//+ "，月供（元）：" + vo.getMonthPrincipalInterest()//+ "，本金（元）：" + vo.getMonthPrincipal()//+ "，利息（元）：" + vo.getMonthInterest()));// //等本等息// List<MoneyVo> list = DBDX(new BigDecimal(MathUtil.centToYuan(principal)), interest, months);// list.forEach(vo -> System.out.println("期数：" + vo.getNumber()//+ "，月供（元）：" + vo.getMonthPrincipalInterest()//+ "，本金（元）：" + vo.getMonthPrincipal()//+ "，利息（元）：" + vo.getMonthInterest()));//先息后本List<MoneyVo> list = XXHB(new BigDecimal(MathUtil.centToYuan(principal)), interest, months);list.forEach(vo -> System.out.println("期数：" + vo.getNumber()+ "，月供（元）：" + vo.getMonthPrincipalInterest()+ "，本金（元）：" + vo.getMonthPrincipal()+ "，利息（元）：" + vo.getMonthInterest()));}/*** 等额本金* 定义：月还款总额逐月降低；月还款本金固定，为贷款总金额/期数；月还款利息逐渐降低，为每月剩余贷款余额*单期利息* 规则：例如【本金10000，月息1%，贷款12期】，则月还款本金=本金/期数；月利息：每期剩余本金*利息，* 如第一期应还利息=10000*1%=100；第二期应还利息=（10000-833.33）*1%=91.67......** @param principal：本金，单位分* @param interest：月利息，单位分* @param months：贷款期数，单位月* @return*/public static List<MoneyVo> DEBJ(BigDecimal principal, Double interest, Integer months) {List<MoneyVo> list = new ArrayList<>();BigDecimal money = principal; //剩余本金BigDecimal monthPrincipal = principal.divide(new BigDecimal(months), 2, BigDecimal.ROUND_HALF_UP); //月还款本金for (int i = 1; i < months + 1; i++) {MoneyVo vo = new MoneyVo();vo.setNumber(i);vo.setMonthPrincipal(monthPrincipal);//月应还利息if (i == 1) {BigDecimal monthInterest = principal.multiply(new BigDecimal(interest).setScale(2, BigDecimal.ROUND_HALF_UP));vo.setMonthInterest(monthInterest);money = principal.subtract(monthPrincipal).setScale(2, BigDecimal.ROUND_HALF_UP);} else {BigDecimal monthInterest = money.multiply(new BigDecimal(interest).setScale(2, BigDecimal.ROUND_HALF_UP)).setScale(2, BigDecimal.ROUND_HALF_UP);vo.setMonthInterest(monthInterest);money = money.subtract(monthPrincipal).setScale(2, BigDecimal.ROUND_HALF_UP);}//月应还本息BigDecimal monthPrincipalInterest = vo.getMonthPrincipal().add(vo.getMonthInterest()).setScale(2, BigDecimal.ROUND_HALF_UP);vo.setMonthPrincipalInterest(monthPrincipalInterest);//整合数据list.add(vo);}return list;}/*** 等本等息* 定义：月还款总额不变；月还款本金不变，为贷款总金额/期数；月还款利息不变，为贷款总金额*单期利率** @param principal：本金，单位分* @param interest：月利息，单位分* @param months：贷款期数，单位月* @return*/public static List<MoneyVo> DBDX(BigDecimal principal, Double interest, Integer months) {List<MoneyVo> list = new ArrayList<>();//月还款本金BigDecimal monthPrincipal = principal.divide(new BigDecimal(months), 2, BigDecimal.ROUND_HALF_UP);//月还款利息BigDecimal monthInterest = principal.multiply(new BigDecimal(interest)).setScale(2, BigDecimal.ROUND_HALF_UP);//月还款本息BigDecimal monthPrincipalInterest = monthPrincipal.add(monthInterest).setScale(2, BigDecimal.ROUND_HALF_UP);for (int i = 1; i < months + 1; i++) {MoneyVo vo = new MoneyVo();vo.setNumber(i);vo.setMonthPrincipal(monthPrincipal);vo.setMonthInterest(monthInterest);vo.setMonthPrincipalInterest(monthPrincipalInterest);list.add(vo);}return list;}/*** 先息后本* 定义：月还款总额不变，为月还款利息；月还款本金为0，在最后一期还总贷款额本金；月还款利息不变，为贷款总金额*单期利息** @param principal：本金，单位分* @param interest：月利息，单位分* @param months：贷款期数，单位月* @return*/public static List<MoneyVo> XXHB(BigDecimal principal, Double interest, Integer months) {List<MoneyVo> list = new ArrayList<>();//月还款本息=月还款利息BigDecimal monthPrincipalInterest = principal.multiply(new BigDecimal(interest)).setScale(2, BigDecimal.ROUND_HALF_UP);for (int i = 1; i < months + 1; i++) {MoneyVo vo = new MoneyVo();vo.setNumber(i);vo.setMonthInterest(monthPrincipalInterest);vo.setMonthPrincipalInterest(monthPrincipalInterest);if (i < months) {vo.setMonthPrincipal(new BigDecimal(0));} else {vo.setMonthPrincipal(principal);}list.add(vo);}return list;}}

package com.alex.examples.utils.money;import java.math.BigDecimal;import java.util.HashMap;import java.util.Map;/*** 等额本息计算工具类** <p>* 等额本息还款，也称定期付息，即借款人每月按相等的金额偿还贷款本息，其中每月贷款利息按月初剩余贷款本金计算并逐月结清。把按揭贷款的本金总额与利息总额相加，* 然后平均分摊到还款期限的每个月中。作为还款人，每个月还给银行固定金额，但每月还款额中的本金比重逐月递增、利息比重逐月递减。* <p>* 年利率＝月利率×12（月）＝日利率×360（天）* <p>* 月利率＝年利率÷12（月）＝日利率×30（天）* <p>* 日利率＝年利率÷360（天）＝月利率÷30（天）。*/public class AverageCapitalPlusInterestUtils {/*** 每月偿还本金和利息* <p>* 公式：每月偿还本息=〔贷款本金×月利率×(1＋月利率)＾还款月数〕÷〔(1＋月利率)＾还款月数-1〕** @param invest总借款额（贷款本金,单位分）* @param yearRate 年利率* @param totalMonth 还款总月数* @return 每月偿还本金和利息(入1 单位分)*/public static double getPerMonthPrincipalInterest(double invest, double yearRate, int totalMonth) {double monthRate = yearRate / 12;double perMonthPrincipalInterest = invest * (monthRate * Math.pow(1 + monthRate, totalMonth)) / (Math.pow(1 + monthRate, totalMonth) - 1);return new BigDecimal(perMonthPrincipalInterest).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();}/*** 等额本息的每月偿还利息* <p>* 公式：每月偿还利息=贷款本金×月利率×〔(1+月利率)^还款月数-(1+月利率)^(还款月序号-1)〕÷〔(1+月利率)^还款月数-1〕** @param invest总借款额（贷款本金,分）* @param yearRate 年利率* @param totalMonth 还款总月数* @return 每月偿还利息(入1 单位分)*/public static Map<Integer, Double> getPerMonthInterest(double invest, double yearRate, int totalMonth) {Map<Integer, Double> map = new HashMap<>();double monthRate = yearRate / 12;double monthInterest;for (int i = 1; i < totalMonth + 1; i++) {double multiply = invest * monthRate;double sub = Math.pow(1 + monthRate, totalMonth) - Math.pow(1 + monthRate, i - 1);monthInterest = multiply * sub / (Math.pow(1 + monthRate, totalMonth) - 1);map.put(i, new BigDecimal(monthInterest).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue());}return map;}/*** 等额本息的每月偿还本金（月还本息-月还利息）** @param invest总借款额（贷款本金,分）* @param yearRate 年利率* @param totalMonth 还款总月数* @return 每月偿还本金(取整舍 单位分)*/public static Map<Integer, Double> getPerMonthPrincipal(double invest, double yearRate, int totalMonth) {double monthRate = yearRate / 12;double monthIncome = invest * monthRate * Math.pow(1 + monthRate, totalMonth)/ (Math.pow(1 + monthRate, totalMonth) - 1);double perMonthPrincipalInterest = new BigDecimal(monthIncome).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();Map<Integer, Double> mapPrincipal = new HashMap<>();double monthInterest;for (int i = 1; i < totalMonth + 1; i++) {Double multiply = invest * monthRate;double sub = (Math.pow(1 + monthRate, totalMonth)) - (Math.pow(1 + monthRate, i - 1));monthInterest = multiply * sub / (Math.pow(1 + monthRate, totalMonth) - 1);double monthInterestL = new BigDecimal(monthInterest).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();mapPrincipal.put(i, new BigDecimal(perMonthPrincipalInterest).subtract(new BigDecimal(monthInterestL)).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue());}return mapPrincipal;}/*** 等额本息的总利息** @param invest总借款额（贷款本金）* @param yearRate 年利率* @param totalMonth 还款总月数* @return 总利息 (单位分)*/public static double getInterestCount(double invest, double yearRate, int totalMonth) {double count = 0;Map<Integer, Double> mapInterest = getPerMonthInterest(invest, yearRate, totalMonth);for (Map.Entry<Integer, Double> entry : mapInterest.entrySet()) {count = new BigDecimal(count).add(new BigDecimal(entry.getValue())).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();}return count;}public static void main(String[] args) {double invest = 10000; // 本金int month = 12;double yearRate = 0.01; // 年利率Double perMonthPrincipalInterest = getPerMonthPrincipalInterest(invest, yearRate, month);System.out.println("等额本息---每月还款本息（每月还款本金+每月还款利息）：" + perMonthPrincipalInterest);Map<Integer, Double> mapPrincipal = getPerMonthPrincipal(invest, yearRate, month);System.out.println("等额本息---每月还款本金：" + mapPrincipal);Map<Integer, Double> mapInterest = getPerMonthInterest(invest, yearRate, month);System.out.println("等额本息---每月还款利息：" + mapInterest);Double count = getInterestCount(invest, yearRate, month);System.out.println("等额本息---总利息：" + count);for (int i = 1; i < month + 1; i++) {if (i < month) {System.out.println("等额本息---" + i + "月还款本金:" + mapPrincipal.get(i) + ",还款利息:" + mapInterest.get(i));//剩余本金：总的本金-每月还款本金invest = new BigDecimal(invest).subtract(new BigDecimal(mapPrincipal.get(i))).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();} else {//最后一个月的还款利息=每月还款本息-剩余本金System.out.println("等额本息---" + i + "月还款本金:" + invest + ",还款利息:" + (new BigDecimal(perMonthPrincipalInterest).subtract(new BigDecimal(invest)).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue()));}}}}