1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/task4/solution13/src/org/apidesign/apifest08/currency/Convertor.java Sat Oct 11 23:38:46 2008 +0200
1.3 @@ -0,0 +1,218 @@
1.4 +package org.apidesign.apifest08.currency;
1.5 +
1.6 +import java.math.BigDecimal;
1.7 +import java.math.MathContext;
1.8 +import java.math.RoundingMode;
1.9 +
1.10 +/** Convertor able to convert amount from one currency to other currency.
1.11 + * <p>
1.12 + * Conversion method are:
1.13 + * <ul>
1.14 + * <li>{@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal)} - convert
1.15 + * using exchange rate specified in exchange rate provide. This method is not try
1.16 + * use reverted excahnage rate.
1.17 + * <li>{@link #convertWithReversibleRates(ConvertorCurrency, ConvertorCurrency, BigDecimal)} -
1.18 + * convert using exchange rate specified in exchange rate provide. This method
1.19 + * is not trying to use reverted exchange rate.
1.20 + * </ul>
1.21 + *
1.22 + * Exchange rate is provided by {@link ExchangeRateProvider}.
1.23 + */
1.24 +public class Convertor {
1.25 + private Convertor[] convertors;
1.26 +
1.27 + /** Create new <code>Convertor</code> as merge of provided convertors. Merged convertor will use
1.28 + * provided convertors to convert between currencies.
1.29 + * <p>
1.30 + * Only one should be able to provide conversion between currencies. If more than one convertos
1.31 + * are able to convert currency, one of conversions will be used (it is not defined which).
1.32 + *
1.33 + * @since version 2
1.34 + * @param convertors Convertor used to create merge-convertor.
1.35 + * @return Returns new convertor instance.
1.36 + */
1.37 + public static Convertor createConvertorAsMerge(Convertor[] convertors) {
1.38 + return new Convertor(convertors);
1.39 + }
1.40 +
1.41 + boolean remainderAllowed = true; //if false, remained is not allowed (should be true ideally, but can't handle it now)
1.42 + ExchangeRateProvider exchangeRateProvider;
1.43 +
1.44 + /** Create simle convertor.
1.45 + */
1.46 + private Convertor() {
1.47 + this.convertors=new Convertor[0];
1.48 + }
1.49 +
1.50 + /** Create merge convertor.
1.51 + */
1.52 + private Convertor(Convertor[] convertors) {
1.53 + this.convertors = convertors;
1.54 + }
1.55 +
1.56 + /**
1.57 + * Create new <code>Convertor</code> using <code>ExchangeRateProvider</code>.
1.58 + *
1.59 + * @param exchangeRateProvider {@link ExchangeRateProvider} used to get exchange rate.
1.60 + *
1.61 + * @return Returns <code>Convertor</code> which can be used to convert money.
1.62 + * @since version1
1.63 + */
1.64 + public static Convertor createConvertor(ExchangeRateProvider exchangeRateProvider) {
1.65 + Convertor c = new Convertor();
1.66 +
1.67 + c.exchangeRateProvider = exchangeRateProvider;
1.68 + return c;
1.69 + }
1.70 +
1.71 + /**
1.72 + * Convert <code>amount</code> from <code>fromCurrency</code> to <code>toCurrency</code> as specified
1.73 + * in <code>ExchangeRateProvider</code>.
1.74 + *
1.75 + * @param amount Amount which should be converted. Can't be negative value (can be zero or positive).
1.76 + * @return Return <code>ConversionResult</code> which holds conversion result.
1.77 + * @since version1
1.78 + * @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
1.79 + */
1.80 + public ConversionResult convert(BigDecimal amount) {
1.81 + return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, false,false);
1.82 + }
1.83 +
1.84 + /**
1.85 + * Convert <code>amount</code> from <code>toCurrency</code> to <code>fromCurrency</code> as specified
1.86 + * in <code>ExchangeRateProvider</code>. This is <em>reverted</em> order than suggested by names of currency fields in <code>ExchangeRate</code>.
1.87 + *
1.88 + * @param amount Amount which should be converted. Can't be negative value (can be zero or positive).
1.89 + * @return Return <code>ConversionResult</code> which holds conversion result.
1.90 + * @since version1
1.91 + * @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
1.92 + */
1.93 + public ConversionResult convertBack(BigDecimal amount) {
1.94 + return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, true,false);
1.95 + }
1.96 +
1.97 + private ConversionResult convertUsingSimpleConvertor(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, boolean reversibleExRate, BigDecimal amount, boolean convertBack) throws ConversionNotSupportedException, RuntimeException {
1.98 + ConversionResult result = new ConversionResult();
1.99 +
1.100 + //ExchangeRate rate = exchangeRateProvider.getExchangeRate();
1.101 + ExchangeRate rate;
1.102 + if (reversibleExRate) {
1.103 + rate = exchangeRateProvider.getReversibleExchangeRate(fromCurrency, toCurrency);
1.104 + } else {
1.105 + rate = exchangeRateProvider.getExchangeRate(fromCurrency, toCurrency);
1.106 + }
1.107 + if (rate == null) {
1.108 + return null;
1.109 + }
1.110 +
1.111 + int fromFranctionDigits = fromCurrency.getDefaultFractionDigits();
1.112 + int toFractionDigits = toCurrency.getDefaultFractionDigits();
1.113 +
1.114 + if (toFractionDigits != 2) {
1.115 + throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getToCurrency() + " has " + toFractionDigits + " defaultFractionDigits");
1.116 + }
1.117 + if (fromFranctionDigits != 2) {
1.118 + throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getFromCurrency() + " has " + fromFranctionDigits + " defaultFractionDigits");
1.119 + }
1.120 +
1.121 + if (amount.signum() == -1) {
1.122 + throw new RuntimeException("Can convert only non-negative value, current value is " + amount);
1.123 + }
1.124 +
1.125 +
1.126 + MathContext context = new MathContext(0, RoundingMode.DOWN);
1.127 +
1.128 + BigDecimal from;
1.129 + BigDecimal to;
1.130 + if (convertBack) {
1.131 + //converting in reverted way
1.132 + to = rate.getFromValue();
1.133 + from = rate.getToValue();
1.134 + } else {
1.135 + //converting in normal way
1.136 + from = rate.getFromValue();
1.137 + to = rate.getToValue();
1.138 + }
1.139 +
1.140 + BigDecimal amountCent = amount.movePointRight(toFractionDigits);
1.141 +
1.142 + final BigDecimal multiplied = amountCent.multiply(to, context);
1.143 + BigDecimal[] division = multiplied.divideAndRemainder(from, context);
1.144 +
1.145 + if (!remainderAllowed && !(BigDecimal.ZERO.equals(division[1]))) {
1.146 + throw new RuntimeException("Remained is not allowed - remaining amount is " + division[1] + " cents");
1.147 + } else {
1.148 + result.setRemainder(BigDecimal.ZERO);
1.149 + }
1.150 +
1.151 + BigDecimal converted = division[0].movePointLeft(toFractionDigits);
1.152 + converted = converted.setScale(toFractionDigits); //XXX ugly
1.153 + result.setConverted(converted);
1.154 + //result.setRemainder(...);
1.155 + return result;
1.156 + }
1.157 +
1.158 +
1.159 + private ConversionResult convertValue(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,BigDecimal amount, boolean convertBack,boolean reversibleExRate) throws RuntimeException {
1.160 + //result.setRemainder(...);
1.161 + if (convertors.length==0) {
1.162 + return convertUsingSimpleConvertor(fromCurrency, toCurrency, reversibleExRate, amount, convertBack);
1.163 + } else {
1.164 + ConversionResult result = null;
1.165 + for (int i = 0;i<convertors.length;i++) {
1.166 + Convertor subConvertor = convertors[i];
1.167 + result = subConvertor.convertValue(fromCurrency, toCurrency, amount, convertBack, reversibleExRate);
1.168 + if (result!=null) {
1.169 + break;
1.170 + }
1.171 + }
1.172 + return result;
1.173 + }
1.174 + }
1.175 +
1.176 + /**
1.177 + * Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
1.178 + * <p>
1.179 + * Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
1.180 + * This method is using only exchange rate from->to and not trying to use reverted excange rate to->from.
1.181 + *
1.182 + * @param fromCurrency Source currency to convert from.
1.183 + * @param toCurrency Target currency to convert to.
1.184 + * @param value Value in source currency which should be converted.
1.185 + * @return Return conversion result.
1.186 + * @since version2
1.187 + * @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code> is not supported.
1.188 + */
1.189 + public ConversionResult convert(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
1.190 + ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,false);
1.191 + if (result==null) {
1.192 + //throw new ConversionNotSupportedException("Conversion from " + fromCurrency + " to " + toCurrency + " is not supported");
1.193 + throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),false);
1.194 + }
1.195 + return result;
1.196 + }
1.197 +
1.198 + /**
1.199 + * Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
1.200 + * Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
1.201 + * <p>
1.202 + * This method is using only exchange rate from->to and if not found, it is trying to use reverted excange rate to->from.
1.203 + *
1.204 + * @param fromCurrency Source currency to convert from.
1.205 + * @param toCurrency Target currency to convert to.
1.206 + * @param value Value in source currency which should be converted.
1.207 + * @return Return conversion result.
1.208 + * @since version2
1.209 + * @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code>
1.210 + * is not supported and neither conversion from <code>toCurrency</code> to <code>fromCurrency</code> is not supported.
1.211 + */
1.212 + public ConversionResult convertWithReversibleRates(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
1.213 + ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,true);
1.214 + if (result==null) {
1.215 + //throw new ConversionNotSupportedException("Neither onversion nor reverted conversion from " + fromCurrency + " to " + toCurrency + " is not supported,");
1.216 + throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),true);
1.217 + }
1.218 + return result;
1.219 + }
1.220 +
1.221 +}