java中每月等额与先息后本计算
一般信用贷款会提供两种还款方式：每月等额或者先息后本。每月等额，就是每月归还等同的部分本金和利息，你手里在使用的本金其实是逐月减少的。先息后本就是先还利息，到期归还本金。
每月等额
1 import java.math.BigDecimal;
2 import java.util.Calendar;
3 import java.util.Date;
4
5 /**
6 * <p>Title: 等额本息还款工具类</p>
7 *
8 */
9 public class CPMUtils{
10
11 /**
12 * <p>Description: 每月还款总额。〔贷款本金×月利率×（1＋月利率）＾还款月数〕÷〔（1＋月利率）＾还款月数－1〕</p>
13 * @param principal 贷款本金
14 * @param monthlyInterestRate 月利率
15 * @param amount 期数
16 * @return
17 */
18 public static BigDecimal monthlyRepayment(BigDecimal principal, BigDecimal monthlyInterestRate, int amount){
19 //（1＋月利率）＾还款月数
20 BigDecimal temp = monthlyInterestRate.add(MoneyUtils.ONE).pow(amount);
21 return principal.multiply(monthlyInterestRate)
22 .multiply(temp)
23 .divide(temp.subtract(MoneyUtils.ONE), MoneyUtils.MATHCONTEXT);
24 }
25
26 /**
27 * <p>Description: 月还款利息。（贷款本金×月利率-月还款额）*（1+月利率)^（当前期数-1）+月还款额</p>
28 * @param principal 贷款本金
29 * @param monthlyInterestRate 月利率
30 * @param monthlyRepayment 月还款额
31 * @param number 当前期数
32 * @return
33 */
34 public static BigDecimal monthlyInterest(BigDecimal principal, BigDecimal monthlyInterestRate, BigDecimal monthlyRepayment, int number){
35 //（1+月利率)^（当前期数-1）
36 BigDecimal temp = monthlyInterestRate.add(MoneyUtils.ONE).pow(number - 1);
37 return principal.multiply(monthlyInterestRate)
38 .subtract(monthlyRepayment)
39 .multiply(temp).add(monthlyRepayment, MoneyUtils.MATHCONTEXT);
41 }
42
43 /**
44 * <p>Description: 还款总利息。期数×贷款本金×月利率×（1＋月利率）^期数÷〔（1＋月利率）^期数－1〕－贷款本金 </p>
45 * @param principal 贷款本金
46 * @param monthlyInterestRate 月利率
47 * @param amount 还款期数
48 * @return
49 */
50 public static BigDecimal interest(BigDecimal principal, BigDecimal monthlyInterestRate, int amount){
51 //（1＋月利率）^期数
52 BigDecimal temp = monthlyInterestRate.add(MoneyUtils.ONE).pow(amount);
53 return new BigDecimal(amount)
54 .multiply(principal)
55 .multiply(monthlyInterestRate)
56 .multiply(temp)
57 .divide(temp.subtract(MoneyUtils.ONE), MoneyUtils.MATHCONTEXT)
58 .subtract(principal, MoneyUtils.MATHCONTEXT);
59 }
60
61 /**
62 * <p>Description: 月还款本金。已经精确到分位，未做单位换算</p>
63 * @param principal 贷款本金
64 * @param monthlyInterestRate 月利率
65 * @param monthlyRepayment 月还款额
66 * @param number 当前期数
67 * @return
68 */
69 public static BigDecimal monthlyPrincipal(BigDecimal principal, BigDecimal monthlyInterestRate, BigDecimal monthlyRepayment, int number){
70 BigDecimal monthInterest = monthlyInterest(principal, monthlyInterestRate, monthlyRepayment, number);
71 //月还款额-月还款利息
72 return monthlyRepayment.subtract(monthInterest).setScale(MoneyUtils.MONEYSHOWSCALE, MoneyUtils.SAVEROUNDINGMODE);
73 }
74
75 /**
76 * <p>Description: 月还款本金。已经精确到分位，未做单位换算</p>
77 * @param monthRepayment 月还款总额
78 * @param monthInterest 月还款利息
79 * @return
80 */
81 public static BigDecimal monthPrincipal(BigDecimal monthRepayment, BigDecimal monthInterest){
82 //月还款总额-月还款利息
83 return monthRepayment.subtract(monthInterest).setScale(MoneyUtils.MONEYSHOWSCALE, MoneyUtils.SAVEROUNDINGMODE);
84 }
85
86 }
先息后本
import java.math.BigDecimal;
/**
* <p>Title: 先息后本还款方式工具类型</p>
*/
public class BIAPPUtils extends RepaymentUtils {
/**
* <p>Description: 月还款利息 贷款本金×月利率 </p>
* @param loan 贷款本金
* @param monthlyInterestRate 月利率
* @return
*/
public static BigDecimal monthlyInterest(BigDecimal loan, BigDecimal monthlyInterestRate){
return loan.multiply(monthlyInterestRate, MoneyUtils.MATHCONTEXT);
}
/**
* <p>Description: 还款总利息 贷款本金×月利率×期数</p>
* @param loan 贷款本金
* @param monthlyInterestRate 月利率
* @param number 期数
* @return
*/
public static BigDecimal interest(BigDecimal loan, BigDecimal monthlyInterestRate, int number){
return loan.multiply(monthlyInterestRate).multiply(new BigDecimal(number), MoneyUtils.MATHCONTEXT);
}
/**
* <p>Description: 月还款额</p>
* @param loan 贷款本金
* @param monthlyInterestRate 月利率
* @param amount 期数
* @param curNumber 当前期数
* @return
*/
public static BigDecimal monthlyRepayment(BigDecimal loan, BigDecimal monthlyInterestRate, int amount, int curNumber){
BigDecimal monthlyInterest = monthlyInterest(loan, monthlyInterestRate);
if(amount == curNumber){
return monthlyInterest.add(loan, MoneyUtils.MATHCONTEXT);//最后月还款额
}else{
return monthlyInterest;
}
}
}
*金额计算工具类
import java.math.BigDecimal;
import java.math.MathContext;
import java.math.RoundingMode;
import java.text.NumberFormat;
public class MoneyUtils {
/**
* 标度（小数位数）
*/
public static final int SCALE = 10;
/**
* 金钱显示标度（小数位数）
*/
public static final int MONEYSHOWSCALE = 2;
/**
* 利率显示标度（小数位数）
*/
public static final int INTERESTRATESHOWSCALE = 4;
/**
* 精度
*/
public static final int PRECISION = 30;
/**
* 保存舍入规则
*/
public static final RoundingMode SAVEROUNDINGMODE = RoundingMode.HALF_UP;
/**
* 是否舍去小数点最后的零
*/
public static boolean STRIPTRAILINGZEROS = true;
/**
* 运算上下文（设置精度、舍入规则）
*/
public static final MathContext MATHCONTEXT = new MathContext(PRECISION, SAVEROUNDINGMODE);
/**
* 每年天数
*/
public static final String YEARDAYS = "360";
/**
* 每年月数
*/
public static final String YEARMOTHS = "12";
/**
* 每月天数
*/
public static final String MOTHDAYS = "30";
/**
* 数字“1”
*/
public static final BigDecimal ONE = new BigDecimal(1);
/**
* 数字“100”
*/
public static final BigDecimal HUNDRED = new BigDecimal(100);
/**
* 数字“0.01”
*/
public static final BigDecimal ONEHUNDREDTH = new BigDecimal(0.01);
public static BigDecimal newBigDecimal(String str){
return (str == null || str.trim().isEmpty()) ? BigDecimal.ZERO : new BigDecimal(str);
}
/**
* <p>Description: 加法返回格式化结果数字</p>
* @param addend
* @param augend
* @return
*/
public static BigDecimal add(BigDecimal addend, BigDecimal augend){
return formatMoney(addend.add(augend, MATHCONTEXT));
}
/**
* <p>Description: 加法返回格式化结果数字</p>
* @param addend
* @param augend
* @return
*/
public static BigDecimal add(String addend, String augend){
BigDecimal decimalAddend = newBigDecimal(addend);
BigDecimal decimalAugend = newBigDecimal(augend);
return formatMoney(decimalAddend.add(decimalAugend, MATHCONTEXT));
}
/**
* <p>Description: 加法返回格式化结果字符串</p>
* @param addend
* @param augend
* @return
*/
public static String addToString(BigDecimal addend, BigDecimal augend){
return formatToString(addend.add(augend, MATHCONTEXT));
}
/**
* <p>Description: 加法返回格式化结果字符串</p>
* @param addend
* @param augend
* @return
*/
public static String addToString(String addend, String augend){
BigDecimal decimalAddend = newBigDecimal(addend);
BigDecimal decimalAugend = newBigDecimal(augend);
return formatToString(decimalAddend.add(decimalAugend, MATHCONTEXT));
}
/**
* <p>Description: 减法返回格式化结果数字</p>
* @param minuend
* @param subtrahend
* @return
*/
public static BigDecimal subtract(BigDecimal minuend, BigDecimal subtrahend){
return formatMoney(minuend.subtract(subtrahend, MATHCONTEXT));
}
/**
* <p>Description: 减法返回格式化结果数字</p>
* @param minuend
* @param subtrahend
* @return
*/
public static BigDecimal subtract(String minuend, String subtrahend){
BigDecimal decimalMinuend = newBigDecimal(minuend);
BigDecimal decimalSubtrahend = newBigDecimal(subtrahend);
return formatMoney(decimalMinuend.subtract(decimalSubtrahend, MATHCONTEXT));
}
/**
* <p>Description: 减法返回格式化结果字符串</p>
* @param minuend
* @param subtrahend
* @return
*/
public static String subtractToString(BigDecimal minuend, BigDecimal subtrahend){
return formatToString(minuend.subtract(subtrahend, MATHCONTEXT));
}
/**
* <p>Description: 减法返回格式化结果字符串</p>
* @param minuend
* @param subtrahend
* @return
*/
public static String subtractToString(String minuend, String subtrahend){
BigDecimal decimalMinuend = newBigDecimal(minuend);
BigDecimal decimalSubtrahend = newBigDecimal(subtrahend);
return formatToString(decimalMinuend.subtract(decimalSubtrahend, MATHCONTEXT));
}
/**
* <p>Description: 乘法返回格式化结果数字</p>
* @param multiplier
* @param multiplicand
* @return
*/
public static BigDecimal multiply(BigDecimal multiplier, BigDecimal multiplicand){
return formatMoney(multiplier.multiply(multiplicand, MATHCONTEXT));
}
/**
* <p>Description: 乘法返回格式化结果数字</p>
* @param multiplier
* @param multiplicand
* @return
*/
public static BigDecimal multiply(String multiplier, String multiplicand){
BigDecimal decimalMultiplier = newBigDecimal(multiplier);
BigDecimal decimalMultiplicand = newBigDecimal(multiplicand);
return formatMoney(decimalMultiplier.multiply(decimalMultiplicand, MATHCONTEXT));
}
/**
* <p>Description: 乘法返回格式化结果字符串</p>
* @param multiplier
* @param multiplicand
* @return
*/
public static String multiplyToString(BigDecimal multiplier, BigDecimal multiplicand){
return formatToString(multiplier.multiply(multiplicand, MATHCONTEXT));
}
/**
* <p>Description: 乘法返回格式化结果字符串</p>
* @param multiplier
* @param multiplicand
* @return
*/
public static String multiplyToString(String multiplier, String multiplicand){
BigDecimal decimalMultiplier = newBigDecimal(multiplier);
BigDecimal decimalMultiplicand = newBigDecimal(multiplicand);
return formatToString(decimalMultiplier.multiply(decimalMultiplicand, MATHCONTEXT));
}
/**
* <p>Description: 除法返回格式化结果数字</p>
* @param dividend
* @param divisor
* @return
*/
public static BigDecimal divide(BigDecimal dividend, BigDecimal divisor){
return formatMoney(dividend.divide(divisor, MATHCONTEXT));
}
/**
* <p>Description: 除法返回格式化结果数字</p>
* @param dividend
* @param divisor
* @return
*/
public static BigDecimal divide(String dividend, String divisor){
BigDecimal decimalDividend = newBigDecimal(dividend);
BigDecimal decimalDivisor = newBigDecimal(divisor);
return formatMoney(decimalDividend.divide(decimalDivisor, MATHCONTEXT));
}
/**
* <p>Description: 除法返回格式化结果字符串</p>
* @param dividend
* @param divisor
* @return
*/
public static String divideToString(BigDecimal dividend, BigDecimal divisor){
return formatToString(dividend.divide(divisor, MATHCONTEXT));
}
/**
* <p>Description: 除法返回格式化结果字符串</p>
* @param dividend
* @param divisor
* @return
*/
public static String divideToString(String dividend, String divisor){
BigDecimal decimalDividend = newBigDecimal(dividend);
BigDecimal decimalDivisor = newBigDecimal(divisor);
return formatToString(decimalDividend.divide(decimalDivisor, MATHCONTEXT));
}
/**
* <p>Description: 月利率计算</p>
* @param yearInterestRate
* @return
*/
public static BigDecimal monthInterestRate(BigDecimal yearInterestRate){
BigDecimal dayInterestRate = MoneyUtils.divide(yearInterestRate, YEARDAYS).setScale(5, RoundingMode.CEILING);
System.err.println(dayInterestRate);
BigDecimal monthInterestRate = dayInterestRate.multiply(newBigDecimal(MOTHDAYS));
System.err.println(monthInterestRate);
return monthInterestRate;
}
/**
* <p>Description: 按既定小数位数格式化金额保存</p>
* @param result
* @return
*/
public static BigDecimal formatMoney(BigDecimal result){
return result.setScale(SCALE, SAVEROUNDINGMODE);
}
/**
* <p>Description: 按既定小数位数格式化金额显示</p>
* @param resultStr 要格式化的数
* @param multiple 乘以的倍数
* @return
*/
public static String formatMoneyToShow(String resultStr, BigDecimal multiple){
BigDecimal result = newBigDecimal(resultStr);
return MoneyUtils.formatToString(MoneyUtils.formatMoneyToShow(result, multiple));
}
/**
* <p>Description: 按既定小数位数格式化金额显示</p>
* @param result 要格式化的数
* @param multiple 乘以的倍数
* @return
*/
public static BigDecimal formatMoneyToShow(BigDecimal result, BigDecimal multiple){
return result.multiply(multiple).setScale(MONEYSHOWSCALE, SAVEROUNDINGMODE);
}
/**
* <p>Description: 按既定小数位数格式化利率显示</p>
* @param result 要格式化的数
* @param multiple 乘以的倍数
* @return
*/
public static BigDecimal formatInterestRateToShow(BigDecimal result, BigDecimal multiple){
return result.multiply(multiple).setScale(INTERESTRATESHOWSCALE, SAVEROUNDINGMODE);
}
/**
* <p>Description: 按既定小数位数格式化显示</p>
* @param result 要格式化的数
* @param scale 显示标度（小数位数）
* @return
*/
public static BigDecimal formatToShow(BigDecimal result, int scale){
return result.setScale(scale, SAVEROUNDINGMODE);
}
/**
* <p>Description: 格式化为字符串，进行去零不去零操作</p>
* @param result
* @return
*/
public static String formatToString(BigDecimal result){
if(result == null){
return "";
}else{
return STRIPTRAILINGZEROS ? result.stripTrailingZeros().toPlainString() : result.toPlainString();
}
}
/**
* <p>Description: 按既定小数位数格式化为货币格式</p>
* @param result
* @return
*/
public static String formatToCurrency(BigDecimal result){
BigDecimal temp = result.divide(HUNDRED, SAVEROUNDINGMODE);
NumberFormat numberFormat = NumberFormat.getCurrencyInstance();
return numberFormat.format(STRIPTRAILINGZEROS ? temp.stripTrailingZeros() : temp);
}
public static String formatToPercent(BigDecimal result){
BigDecimal temp = result.divide(HUNDRED, SAVEROUNDINGMODE);
NumberFormat numberFormat = NumberFormat.getPercentInstance();
return numberFormat.format(STRIPTRAILINGZEROS ? temp.stripTrailingZeros() : temp);
}
/**
* <p>Description:格式化数字为千分位显示； </p>
* @param text
* @return
*/
public static String fmtMicrometer(String text){
DecimalFormat df = null;
if(text.indexOf(".") > 0) {
if(text.length() - text.indexOf(".")-1 == 0){
df = new DecimalFormat("###,##0.");
}else if(text.length() - text.indexOf(".")-1 == 1){
df = new DecimalFormat("###,##0.0");
}else {
df = new DecimalFormat("###,##0.00");
}
}else{
df = new DecimalFormat("###,##0.00");
}
double number = 0.0;
try {
number = Double.parseDouble(text);
} catch (Exception e) {
number = 0.0;
}
return df.format(number);
}
}