/*** Description:等額本金工具類*/import com.google.common.collect.Maps;import java.math.BigDecimal; import java.util.HashMap; import java.util.Map; import java.util.Set;/*** 等額本金是指一種貸款的還款方式，是在還款期內把貸款數總額等分，每月償還同等數額的本金和剩余貸款在該月所產生的利息，這樣由于每月的還款本金額固定，* 而利息越來越少，借款人起初還款壓力較大，但是隨時間的推移每月還款數也越來越少。*/ public class AverageCapitalUtils {/*** 等額本金計算獲取還款方式為等額本金的每月償還本金和利息** 公式：每月償還本金=(貸款本金÷還款月數)+(貸款本金-已歸還本金累計額)×月利率** @param invest* 總借款額（貸款本金）* @param yearRate* 年利率* @param month* 還款總月數* @return 每月償還本金和利息,不四舍五入，直接截取小數點最后兩位*/public static Map<Integer, Double> getPerMonthPrincipalInterest(double invest, double yearRate, int totalMonth) {Map<Integer, Double> map = new HashMap<Integer, Double>();// 每月本金double monthPri = getPerMonthPrincipal(invest, totalMonth);// 獲取月利率double monthRate = yearRate / 12;monthRate = new BigDecimal(monthRate).setScale(6, BigDecimal.ROUND_DOWN).doubleValue();for (int i = 1; i <= totalMonth; i++) {double monthRes = monthPri + (invest - monthPri * (i - 1)) * monthRate;monthRes = new BigDecimal(monthRes).setScale(2, BigDecimal.ROUND_DOWN).doubleValue();map.put(i, monthRes);}return map;}/*** 等額本金計算獲取還款方式為等額本金的每月償還利息** 公式：每月應還利息=剩余本金×月利率=(貸款本金-已歸還本金累計額)×月利率** @param invest* 總借款額（貸款本金）* @param yearRate* 年利率* @param month* 還款總月數* @return 每月償還利息*/public static Map<Integer, Double> getPerMonthInterest(double invest, double yearRate, int totalMonth) {Map<Integer, Double> inMap = new HashMap<Integer, Double>();double principal = getPerMonthPrincipal(invest, totalMonth);Map<Integer, Double> map = getPerMonthPrincipalInterest(invest, yearRate, totalMonth);for (Map.Entry<Integer, Double> entry : map.entrySet()) {BigDecimal principalBigDecimal = new BigDecimal(principal);BigDecimal principalInterestBigDecimal = new BigDecimal(entry.getValue());BigDecimal interestBigDecimal = principalInterestBigDecimal.subtract(principalBigDecimal);interestBigDecimal = interestBigDecimal.setScale(2, BigDecimal.ROUND_DOWN);inMap.put(entry.getKey(), interestBigDecimal.doubleValue());}return inMap;}/*** 等額本金計算獲取還款方式為等額本金的每月償還本金** 公式：每月應還本金=貸款本金÷還款月數** @param invest* 總借款額（貸款本金）* @param yearRate* 年利率* @param month* 還款總月數* @return 每月償還本金*/public static double getPerMonthPrincipal(double invest, int totalMonth) {BigDecimal monthIncome = new BigDecimal(invest).divide(new BigDecimal(totalMonth), 2, BigDecimal.ROUND_DOWN);return monthIncome.doubleValue();}/*** 等額本金計算獲取還款方式為等額本金的總利息** @param invest* 總借款額（貸款本金）* @param yearRate* 年利率* @param month* 還款總月數* @return 總利息*/public static double getInterestCount(double invest, double yearRate, int totalMonth) {BigDecimal count = new BigDecimal(0);Map<Integer, Double> mapInterest = getPerMonthInterest(invest, yearRate, totalMonth);for (Map.Entry<Integer, Double> entry : mapInterest.entrySet()) {count = count.add(new BigDecimal(entry.getValue()));}return count.doubleValue();}/*** @param args*/public static void main(String[] args) {double invest = 800000; // 本金int month = 120;double yearRate = 0.052; // 年利率Map<Integer, Double> getPerMonthPrincipalInterest = getPerMonthPrincipalInterest(invest, yearRate, month);System.out.println("等額本金---每月本息：" + getPerMonthPrincipalInterest);double benjin = getPerMonthPrincipal(invest, month);System.out.println("等額本金---每月本金:" + benjin);Map<Integer, Double> mapInterest = getPerMonthInterest(invest, yearRate, month);System.out.println("等額本金---每月利息:" + mapInterest);Map<Integer, Double> mapInterestCount = Maps.newHashMap();for(Map.Entry<Integer, Double> entry : mapInterest.entrySet()){int curMonth = entry.getKey();Double curIntersetCount = 0d;if(curMonth > 1){curIntersetCount = entry.getValue() + mapInterestCount.get(curMonth - 1);}else {curIntersetCount = entry.getValue();}Double value = new BigDecimal(String.valueOf(curIntersetCount)).setScale(2, BigDecimal.ROUND_DOWN).doubleValue();mapInterestCount.put(curMonth, value);}System.out.println("等額本金---各月加和:" + mapInterestCount);double count = getInterestCount(invest, yearRate, month);System.out.println("等額本金---總利息：" + count);} } import com.google.common.collect.Maps;import java.math.BigDecimal; import java.util.HashMap; import java.util.Map;public class AverageCapitalPlusInterestUtils {/*** 等額本息計算獲取還款方式為等額本息的每月償還本金和利息* <p>* 公式：每月償還本息=〔貸款本金×月利率×(1＋月利率)＾還款月數〕÷〔(1＋月利率)＾還款月數-1〕** @param invest 總借款額（貸款本金）* @param yearRate 年利率* @param month 還款總月數* @return 每月償還本金和利息, 不四舍五入，直接截取小數點最后兩位*/public static double getPerMonthPrincipalInterest(double invest, double yearRate, int totalmonth) {double monthRate = yearRate / 12;BigDecimal monthIncome = new BigDecimal(invest).multiply(new BigDecimal(monthRate * Math.pow(1 + monthRate, totalmonth))).divide(new BigDecimal(Math.pow(1 + monthRate, totalmonth) - 1), 2, BigDecimal.ROUND_DOWN);return monthIncome.doubleValue();}/*** 等額本息計算獲取還款方式為等額本息的每月償還利息* <p>* 公式：每月償還利息=貸款本金×月利率×〔(1+月利率)^還款月數-(1+月利率)^(還款月序號-1)〕÷〔(1+月利率)^還款月數-1〕** @param invest 總借款額（貸款本金）* @param yearRate 年利率* @param month 還款總月數* @return 每月償還利息*/public static Map<Integer, BigDecimal> getPerMonthInterest(double invest, double yearRate, int totalmonth) {Map<Integer, BigDecimal> map = new HashMap<Integer, BigDecimal>();double monthRate = yearRate / 12;BigDecimal monthInterest;for (int i = 1; i < totalmonth + 1; i++) {BigDecimal multiply = new BigDecimal(invest).multiply(new BigDecimal(monthRate));BigDecimal sub = new BigDecimal(Math.pow(1 + monthRate, totalmonth)).subtract(new BigDecimal(Math.pow(1 + monthRate, i - 1)));monthInterest = multiply.multiply(sub).divide(new BigDecimal(Math.pow(1 + monthRate, totalmonth) - 1), 6, BigDecimal.ROUND_DOWN);monthInterest = monthInterest.setScale(2, BigDecimal.ROUND_DOWN);map.put(i, monthInterest);}return map;}/*** 等額本息計算獲取還款方式為等額本息的每月償還本金** @param invest 總借款額（貸款本金）* @param yearRate 年利率* @param month 還款總月數* @return 每月償還本金*/public static Map<Integer, BigDecimal> getPerMonthPrincipal(double invest, double yearRate, int totalmonth) {double monthRate = yearRate / 12;BigDecimal monthIncome = new BigDecimal(invest).multiply(new BigDecimal(monthRate * Math.pow(1 + monthRate, totalmonth))).divide(new BigDecimal(Math.pow(1 + monthRate, totalmonth) - 1), 2, BigDecimal.ROUND_DOWN);Map<Integer, BigDecimal> mapInterest = getPerMonthInterest(invest, yearRate, totalmonth);Map<Integer, BigDecimal> mapPrincipal = new HashMap<Integer, BigDecimal>();for (Map.Entry<Integer, BigDecimal> entry : mapInterest.entrySet()) {mapPrincipal.put(entry.getKey(), monthIncome.subtract(entry.getValue()));}return mapPrincipal;}/*** 等額本息計算獲取還款方式為等額本息的總利息** @param invest 總借款額（貸款本金）* @param yearRate 年利率* @param month 還款總月數* @return 總利息*/public static double getInterestCount(double invest, double yearRate, int totalmonth) {BigDecimal count = new BigDecimal(0);Map<Integer, BigDecimal> mapInterest = getPerMonthInterest(invest, yearRate, totalmonth);for (Map.Entry<Integer, BigDecimal> entry : mapInterest.entrySet()) {count = count.add(entry.getValue());}return count.doubleValue();}/*** 應還本金總和** @param invest 總借款額（貸款本金）* @param yearRate 年利率* @param month 還款總月數* @return 應還本金總和*/public static double getPrincipalInterestCount(double invest, double yearRate, int totalmonth) {double monthRate = yearRate / 12;BigDecimal perMonthInterest = new BigDecimal(invest).multiply(new BigDecimal(monthRate * Math.pow(1 + monthRate, totalmonth))).divide(new BigDecimal(Math.pow(1 + monthRate, totalmonth) - 1), 2, BigDecimal.ROUND_DOWN);BigDecimal count = perMonthInterest.multiply(new BigDecimal(totalmonth));count = count.setScale(2, BigDecimal.ROUND_DOWN);return count.doubleValue();}/*** @param args*/public static void main(String[] args) {double invest = 800000; // 本金int month = 120;double yearRate = 0.052; // 年利率double perMonthPrincipalInterest = getPerMonthPrincipalInterest(invest, yearRate, month);System.out.println("等額本息---每月還款本息：" + perMonthPrincipalInterest);Map<Integer, BigDecimal> mapInterest = getPerMonthInterest(invest, yearRate, month);System.out.println("等額本息---每月還款利息：" + mapInterest);Map<Integer, BigDecimal> mapInterestCount = Maps.newHashMap();for(Map.Entry<Integer, BigDecimal> entry : mapInterest.entrySet()){int curMonth = entry.getKey();BigDecimal curIntersetCount = new BigDecimal(0);if(curMonth > 1){curIntersetCount = entry.getValue().add(mapInterestCount.get(curMonth - 1));}else {curIntersetCount = entry.getValue();}mapInterestCount.put(curMonth, curIntersetCount);}System.out.println("等額本金---各月加和:" + mapInterestCount);Map<Integer, BigDecimal> mapPrincipal = getPerMonthPrincipal(invest, yearRate, month);System.out.println("等額本息---每月還款本金：" + mapPrincipal);double count = getInterestCount(invest, yearRate, month);System.out.println("等額本息---總利息：" + count);double principalInterestCount = getPrincipalInterestCount(invest, yearRate, month);System.out.println("等額本息---應還本息總和：" + principalInterestCount);} }

import com.google.common.collect.Maps;import java.math.BigDecimal; import java.util.Map;/*** 提前還貸款：http://www.zuhedaikuan.com/jsq/tiqian.aspx*/ public class House {public static void main(String[] args) {testHose(580000, 0.052, 60);System.out.println();System.out.println();System.out.println();testHose(500000, 0.0325, 120);}public static void testHose(double invest, double yearRate, int month){Map<Integer, Double> getPerMonthPrincipalInterest = AverageCapitalUtils.getPerMonthPrincipalInterest(invest, yearRate, month);System.out.println("等額本金---每月本息：" + getPerMonthPrincipalInterest);double perMonthPrincipalInterestPlus = AverageCapitalPlusInterestUtils.getPerMonthPrincipalInterest(invest, yearRate, month);System.out.println("等額本息---每月本息：" + perMonthPrincipalInterestPlus);System.out.println();double benjin = AverageCapitalUtils.getPerMonthPrincipal(invest, month);System.out.println("等額本金---每月本金：" + benjin);Map<Integer, BigDecimal> mapPrincipalPlus = AverageCapitalPlusInterestUtils.getPerMonthPrincipal(invest, yearRate, month);System.out.println("等額本息---每月本金：" + mapPrincipalPlus);System.out.println();double benjinMonth = AverageCapitalUtils.getPerMonthPrincipal(invest, month);Map<Integer, BigDecimal> benjinAll = Maps.newHashMap();for(int i=0; i<month ;i++){if(i == 0){benjinAll.put(i + 1, new BigDecimal(String.valueOf(benjinMonth)));}else {benjinAll.put(i + 1, benjinAll.get(i).add(new BigDecimal(String.valueOf(benjinMonth))));}}System.out.println("等額本金---已還本金：" + benjinAll);Map<Integer, BigDecimal> mapPrincipalAll = Maps.newHashMap();for(Map.Entry<Integer, BigDecimal> entry : AverageCapitalPlusInterestUtils.getPerMonthPrincipal(invest, yearRate, month).entrySet()) {int curMonth = entry.getKey();BigDecimal curIntersetCount = new BigDecimal(0);if(curMonth > 1){curIntersetCount = entry.getValue().add(mapPrincipalAll.get(curMonth - 1));}else {curIntersetCount = entry.getValue();}mapPrincipalAll.put(curMonth, curIntersetCount);}System.out.println("等額本息---已還本金：" + mapPrincipalAll);System.out.println();Map<Integer, Double> mapInterest = AverageCapitalUtils.getPerMonthInterest(invest, yearRate, month);System.out.println("等額本金---每月利息：" + mapInterest);Map<Integer, BigDecimal> mapInterestPlus = AverageCapitalPlusInterestUtils.getPerMonthInterest(invest, yearRate, month);System.out.println("等額本息---每月利息：" + mapInterestPlus);System.out.println();Map<Integer, Double> mapInterestCount = Maps.newHashMap();for(Map.Entry<Integer, Double> entry : mapInterest.entrySet()){int curMonth = entry.getKey();Double curIntersetCount = 0d;if(curMonth > 1){curIntersetCount = entry.getValue() + mapInterestCount.get(curMonth - 1);}else {curIntersetCount = entry.getValue();}Double value = new BigDecimal(String.valueOf(curIntersetCount)).setScale(2, BigDecimal.ROUND_DOWN).doubleValue();mapInterestCount.put(curMonth, value);}System.out.println("等額本金---各月加和：" + mapInterestCount);Map<Integer, BigDecimal> mapInterestCountPlus = Maps.newHashMap();for(Map.Entry<Integer, BigDecimal> entry : mapInterestPlus.entrySet()){int curMonth = entry.getKey();BigDecimal curIntersetCountPlus = new BigDecimal(0);if(curMonth > 1){curIntersetCountPlus = entry.getValue().add(mapInterestCountPlus.get(curMonth - 1));}else {curIntersetCountPlus = entry.getValue();}mapInterestCountPlus.put(curMonth, curIntersetCountPlus);}System.out.println("等額本金---各月加和：" + mapInterestCountPlus);System.out.println();double beforecount = AverageCapitalUtils.getInterestCount(invest, yearRate, month);System.out.println("等額本金---總利息：" + beforecount);double beforecountPlus = AverageCapitalPlusInterestUtils.getInterestCount(invest, yearRate, month);System.out.println("等額本息---總利息：" + beforecountPlus);} }

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