我编写的计算按揭记录明细类

计算按揭明细记录的类：

import java.io.FileInputStream;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * @author Alfoo Liu <[e-mail]>
 * @since 2011-11-01 09:58
 */
public class MortgageCalculator {
    final static String default_config_file_name = "MortgageCalculator.properties";
    SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd");
    DecimalFormat df = new DecimalFormat("0.00");
    DecimalFormat dfl = new DecimalFormat("0.0000");
    private Properties configuration = new Properties();

    public MortgageCalculator(String configFilePath) {
        df.setRoundingMode(RoundingMode.UP);
        dfl.setRoundingMode(RoundingMode.UP);

        loadProperties(configFilePath);
    }

    public void loadProperties(String filePath) {
        try {
            FileInputStream fileInputStream = new FileInputStream(filePath);
            configuration.load(fileInputStream);
        } catch (FileNotFoundException fnfe) {
            InputStream resourceAsStream = getClass().getResourceAsStream(default_config_file_name);
            try {
                configuration.load(resourceAsStream);
            } catch (IOException e) {
                System.err.println("failed read config file: " + default_config_file_name + " from classpath "
                        + this.getClass().getPackage().getName());
            }
        } catch (IOException ioe) {
            System.err.println("failed read config file: " + filePath);
        }
    }

    public Properties getConfiguration() {
        return configuration;
    }

    public void printMortgageDetailInfo(List<MortgageBean> payList) {
        for (MortgageBean bean : payList) {
            System.out.println(bean.toString());
        }
    }

    /**
     * calculte method: (total - benjin_money * cur_month) * rate_month + benjin_money;
     * @return List pay list;
     */
    public List<MortgageBean> calculate() {
        List<MortgageBean> payList = new ArrayList<MortgageBean>();
        int period = getPeriod(), restPeriod;
        double totalPrincipal = getTotalPrincipal();
        String currentDateStr = getFirstPayDate();
        double restPrincipal = totalPrincipal, interest, principal, rate, monthRate;

        rate = getFirstPayRate();

        Date currentDate;

        MortgageBean mortgageBean;
        for (int i = 1; i <= period; i++) {
            monthRate = toDouble( dfl.format( rate / 12 ) );

            restPeriod = period - i + 1;
            principal = toDouble( df.format( (restPrincipal / restPeriod) ) );
            String tiqianhuankuanDate = getConfiguration().getProperty("tiqianhuankuanDate");
            if (null != tiqianhuankuanDate && tiqianhuankuanDate.equals(currentDateStr)) {
                principal += toDouble( getConfiguration().getProperty("tiqianhuankuanMoney", "0") );
            }
            interest = toDouble( df.format( (restPrincipal - principal) * monthRate ) );

            restPrincipal = toDouble(df.format(restPrincipal - principal));


            currentDate = getDate(currentDateStr);

            mortgageBean = new MortgageBean(currentDate, i, rate, toDouble( df.format(principal + interest) ),
                    principal, interest, restPrincipal);
            payList.add(mortgageBean);

            currentDateStr = getNextPayDate(currentDate);
            rate = toDouble( dfl.format( getNextPayRate(currentDate, rate) ) );
        }

        return payList;
    }

    protected double toDouble(String dv) {
        return Double.parseDouble(dv);
    }

    private double getDiscount() {
        return Double.parseDouble(getConfiguration().getProperty("rateDiscount"));
    }

    private int getPeriod() {
        return Integer.parseInt( getConfiguration().getProperty("periods") );
    }

    private double getTotalPrincipal() {
        return Double.parseDouble(getConfiguration().getProperty("totalPrincipal"));
    }

    private String getFirstPayDate() {
        return configuration.getProperty("firstMortgageDate");
    }

    private Date getDate(String date) {
        try {
            return format.parse(date);
        } catch (ParseException e) {
            System.err.println("invalid date format: " + date);
            return null;
        }
    }

    private double getFirstPayRate() {
        String firstPayDate = "MortgageRate." + getFirstPayDate();
        String firstRateStr = configuration.getProperty(firstPayDate);
        double v = Double.parseDouble(firstRateStr)/100 * getDiscount();
        return toDouble( dfl.format(v) );
    }

    private String getNextPayDate(Date date) {
        GregorianCalendar gc = new GregorianCalendar(Locale.SIMPLIFIED_CHINESE);
        gc.setTime(date);
        gc.add(Calendar.MONTH, 1);

        Date nextMonth = gc.getTime();
        return format.format(nextMonth);
    }

    private double getNextPayRate(Date date, double lastPayRate) {
        String property = configuration.getProperty("MortgageRate." + getNextPayDate(date));

        if (null == property) {
            return lastPayRate;
        }

        double v = Double.parseDouble(property) * getDiscount() / 100;
        return toDouble( dfl.format(v) );
    }


    public static void main(String[] args) {
        MortgageCalculator calculator = new MortgageCalculator("");
        calculator.loadProperties("");
        List<MortgageBean> mortgageBeanList = calculator.calculate();
        calculator.printMortgageDetailInfo(mortgageBeanList);
    }
}

按揭的Bean类：

import java.io.Serializable;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @author Alfoo Liu <[e-mail]>
 * @since 2011-11-01 10:36
 */
public class MortgageBean implements Serializable {
    DecimalFormat df = new DecimalFormat("0.00");
    DecimalFormat dfl = new DecimalFormat("0.00%");
    final static SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    final static String DELIMETER = "\t\t";
    private Date mortgageDate;
    private int mortgageNumber;
    private double rate;
    /*当前月份还的款总额*/
    private double currentMonthPay;
    /*当前月份还的本金*/
    private double currentMonthPrincipal;
    /*当前月还的利息*/
    private double currentMonthInterest;
    /*剩余本金*/
    private double restPrincipal;

    public MortgageBean(Date mortgageDate, int mortgageNumber, double rate, double currentMonthPay,
                        double currentMonthPrincipal, double currentMonthInterest, double restPrincipal) {
        this.mortgageDate = mortgageDate;
        this.mortgageNumber = mortgageNumber;
        this.rate = rate;
        this.currentMonthPay = currentMonthPay;
        this.currentMonthPrincipal = currentMonthPrincipal;
        this.currentMonthInterest = currentMonthInterest;
        this.restPrincipal = restPrincipal;
    }

    public Date getMortgageDate() {
        return mortgageDate;
    }

    public void setMortgageDate(Date mortgageDate) {
        this.mortgageDate = mortgageDate;
    }

    public int getMortgageNumber() {
        return mortgageNumber;
    }

    public void setMortgageNumber(int mortgageNumber) {
        this.mortgageNumber = mortgageNumber;
    }

    public double getRate() {
        return rate;
    }

    public void setRate(float rate) {
        this.rate = rate;
    }

    public double getCurrentMonthPay() {
        return currentMonthPay;
    }

    public void setCurrentMonthPay(float currentMonthPay) {
        this.currentMonthPay = currentMonthPay;
    }

    public double getCurrentMonthPrincipal() {
        return currentMonthPrincipal;
    }

    public void setCurrentMonthPrincipal(float currentMonthPrincipal) {
        this.currentMonthPrincipal = currentMonthPrincipal;
    }

    public double getCurrentMonthInterest() {
        return currentMonthInterest;
    }

    public void setCurrentMonthInterest(float currentMonthInterest) {
        this.currentMonthInterest = currentMonthInterest;
    }

    public double getRestPrincipal() {
        return restPrincipal;
    }

    public void setRestPrincipal(float restPrincipal) {
        this.restPrincipal = restPrincipal;
    }

    @Override public String toString() {
        StringBuilder sb = new StringBuilder();

        sb.append(format.format( getMortgageDate() ));
        sb.append(DELIMETER);
        sb.append( getMortgageNumber() );
        sb.append(DELIMETER);

        sb.append( dfl.format(getRate()) );
        sb.append(DELIMETER);
        sb.append( df.format(getCurrentMonthPay()) );
        sb.append(DELIMETER);
        sb.append( df.format(getCurrentMonthPrincipal()) );
        sb.append(DELIMETER);
        sb.append( df.format(getCurrentMonthInterest()) );
        sb.append(DELIMETER);
        sb.append( df.format(getRestPrincipal()) );

        return sb.toString();
    }
}

配置文件，放在这个类相同的目录下：

#如果你家的还款日期是26号，则把日期的末两位全部改成26，日期格式为yyyyMMdd
#format: yyyyMMdd
firstMortgageDate=20100326
#第一次还款的利率
firstMortgageRate=5.94
#利率折扣
rateDiscount=0.7
#Unit: Month
periods=240
#Unit: yuan
totalPrincipal=300000
#提前还款月份
tiqianhuankuanDate=20111226
#Unit: yuan
tiqianhuankuanMoney=80000


#各期还款利率
MortgageRate.20100326=5.94
MortgageRate.20101026=6.14
MortgageRate.20101226=6.40
MortgageRate.20110226=6.60
MortgageRate.20110426=6.80
MortgageRate.20110726=7.05