Java实现等额本息

绝地灬酷狼 2021-11-17 23:22 324阅读 0赞

import java.math.BigDecimal;
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.HashMap;
    import java.util.Map;
    
    /**
     * 等额本息
     */
    public class EqualPrincipalInterestUtil {
    
    	/**
    	 * 每期本金+利息
    	 * 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
    	 *            本金
    	 * @param periodRate
    	 *            每期利率
    	 * @param periodMonthNum
    	 *            期数
    	 * @return
    	 */
    	public static double getPerPeriodPrincipalInterest(double invest, double periodRate, int periodMonthNum) {
    		BigDecimal monthIncome = new BigDecimal(invest)
    				.multiply(new BigDecimal(periodRate * Math.pow(1 + periodRate, periodMonthNum)))
    				.divide(new BigDecimal(Math.pow(1 + periodRate, periodMonthNum) - 1), 4, BigDecimal.ROUND_HALF_UP);
    		return monthIncome.doubleValue();
    	}
    
    	/**
    	 * 每期利息
    	 * 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
    	 *            本金
    	 * @param periodRate
    	 *            每期利率
    	 * @param periodMonthNum
    	 *            期数
    	 * @return
    	 */
    	public static Map<Integer, BigDecimal> getPerPeriodInterest(double invest, double periodRate, int periodMonthNum) {
    		Map<Integer, BigDecimal> map = new HashMap<Integer, BigDecimal>();
    		BigDecimal periodInterest;
    		for (int i = 1; i < periodMonthNum + 1; i++) {
    			BigDecimal multiply = new BigDecimal(invest).multiply(new BigDecimal(periodRate));
    			BigDecimal sub = new BigDecimal(Math.pow(1 + periodRate, periodMonthNum))
    					.subtract(new BigDecimal(Math.pow(1 + periodRate, i - 1)));
    			periodInterest = multiply.multiply(sub).divide(new BigDecimal(Math.pow(1 + periodRate, periodMonthNum) - 1),
    					6, BigDecimal.ROUND_HALF_UP);
    			periodInterest = periodInterest.setScale(4, BigDecimal.ROUND_HALF_UP);
    			map.put(i, periodInterest);
    		}
    		return map;
    	}
    
    	/**
    	 * 每期还款本金
    	 * 
    	 * @param invest
    	 *            本金
    	 * @param periodRate
    	 *            每期利率
    	 * @param periodNum
    	 *            期数
    	 * @return
    	 */
    	public static Map<Integer, BigDecimal> getPerPeriodPrincipal(double invest, double periodRate, int periodNum) {
    		BigDecimal monthIncome = new BigDecimal(invest)
    				.multiply(new BigDecimal(periodRate * Math.pow(1 + periodRate, periodNum)))
    				.divide(new BigDecimal(Math.pow(1 + periodRate, periodNum) - 1), 4, BigDecimal.ROUND_HALF_UP);
    		Map<Integer, BigDecimal> mapInterest = getPerPeriodInterest(invest, periodRate, periodNum);
    		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;
    	}
    
    	/**
    	 * 总利息
    	 * 
    	 * @param invest
    	 *            本金
    	 * @param periodRate
    	 *            每期利率
    	 * @param periodNum
    	 *            期数
    	 * @return
    	 */
    	public static double getInterestCount(double invest, double periodRate, int periodNum) {
    		BigDecimal count = new BigDecimal(0);
    		Map<Integer, BigDecimal> mapInterest = getPerPeriodInterest(invest, periodRate, periodNum);
    
    		for (Map.Entry<Integer, BigDecimal> entry : mapInterest.entrySet()) {
    			count = count.add(entry.getValue());
    		}
    		return count.doubleValue();
    	}
    
    	/**
    	 * 本息总和
    	 * 
    	 * @param invest
    	 *            本金
    	 * @param periodRate
    	 *            每期利率
    	 * @param periodNum
    	 *            期数
    	 * @return
    	 */
    	public static double getPrincipalInterestCount(double invest, double periodRate, int periodNum) {
    		BigDecimal perMonthInterest = new BigDecimal(invest);
    		Map<Integer, BigDecimal> mapInterest = getPerPeriodInterest(invest, periodRate, periodNum);
    		for (Map.Entry<Integer, BigDecimal> entry : mapInterest.entrySet()) {
    			perMonthInterest = perMonthInterest.add(entry.getValue());
    		}
    		return perMonthInterest.doubleValue();
    	}
    
    	/**
    	 * 每期还款日期
    	 * @param start_date
    	 * 				起租日
    	 * @param perPeriodMonthNum
    	 * 				每期月数
    	 * @param periodNum
    	 * 				期数
    	 * @return
    	 */
    	public static Map<Integer, String> getRepaymentDate(String start_date, int perPeriodMonthNum, int periodNum) {
    		Map<Integer, String> periodRepaymentDate = new HashMap<Integer, String>();
    		String nextRepaymentDate = start_date;
    		periodRepaymentDate.put(1, nextRepaymentDate);
    		for (int i = 2; i < periodNum + 1; i++) {
    			nextRepaymentDate = getMonthAdd(perPeriodMonthNum, nextRepaymentDate, "yyyyMMdd");
    			periodRepaymentDate.put(i, nextRepaymentDate);
    		}
    		return periodRepaymentDate;
    	}
    
    	/**
    	 * 功能描述：返回指定日期加上多少月之后的时间<BR>
    	 * @param from   yyyyMMdd
    	 * @param day
    	 * @param formatStr
    	 * @return
    	 */
    	public static String getMonthAdd(int day,String from,String formatStr){
    		SimpleDateFormat sdf=new SimpleDateFormat(formatStr);
    		Calendar calendar = Calendar.getInstance();
    		try {
    			calendar.setTime(sdf.parse(from));
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    		calendar.add(Calendar.MONTH, day);
    		String date = sdf.format(calendar.getTime());
    		return date;
    	}
    	
    	public static void main(String[] args) {  
            double invest = 10000; // 本金  
            int periodNum = 4;
            double periodRate = 0.12/3; // 年利率  
            System.out.println("等额本息---本金：" + invest);  
            double perMonthPrincipalInterest = getPerPeriodPrincipalInterest(invest, periodRate, periodNum);  
            System.out.println("等额本息---每期还款本息：" + perMonthPrincipalInterest);  
            Map<Integer, BigDecimal> mapInterest = getPerPeriodInterest(invest, periodRate, periodNum);  
            System.out.println("等额本息---每期还款利息：" + mapInterest);  
            Map<Integer, BigDecimal> mapPrincipal = getPerPeriodPrincipal(invest, periodRate, periodNum);  
            System.out.println("等额本息---每期还款本金：" + mapPrincipal);  
            double count = getInterestCount(invest, periodRate, periodNum);  
            System.out.println("等额本息---总利息：" + count);  
            double principalInterestCount = getPrincipalInterestCount(invest, periodRate, periodNum);  
            System.out.println("等额本息---应还本息总和：" + principalInterestCount);  
        }
    }