1.1 --- a/task2/solution06/src/org/apidesign/apifest08/currency/Convertor.java Tue Oct 07 00:25:53 2008 +0200
1.2 +++ b/task2/solution06/src/org/apidesign/apifest08/currency/Convertor.java Tue Oct 07 00:42:57 2008 +0200
1.3 @@ -4,23 +4,44 @@
1.4
1.5 import java.math.BigDecimal;
1.6 import java.math.RoundingMode;
1.7 +import java.util.ArrayList;
1.8 import java.util.Currency;
1.9 +import java.util.List;
1.10
1.11 public final class Convertor {
1.12
1.13 - private final Currency first;
1.14 - private final Currency second;
1.15 - private final BigDecimal rateValue; // a rate between the first currency and the second currency
1.16 - public static final BigDecimal one = new BigDecimal(1);
1.17 + private List<ConvertorDelegate> convertorDelegates = new ArrayList<ConvertorDelegate>();
1.18
1.19 +
1.20 + /**
1.21 + * Create new instance of the converter for the given currencies and its rate.
1.22 + *
1.23 + * @param rateValue the rate between the first and the second currency
1.24 + * @param currencyFirst the first currency
1.25 + * @param currencySecond the second currency
1.26 + */
1.27 public Convertor(BigDecimal rateValue, Currency currencyFirst, Currency currencySecond) {
1.28 notNull(currencyFirst, "currencyFirst");
1.29 notNull(currencySecond, "currencySecond");
1.30 - notNull(rateValue, "rateValue");
1.31 + notNull(rateValue, "rateValue");
1.32 + convertorDelegates.add(new ConvertorDelegate(rateValue, currencyFirst, currencySecond));
1.33 + }
1.34 +
1.35 + /**
1.36 + * Create new instance of the convertor from the given convertors.
1.37 + * @param convertors the convertors
1.38 + */
1.39 + public Convertor(Convertor... convertors) {
1.40 + notNull(convertors, "convertors");
1.41 + if(convertors.length == 0) {
1.42 + throw new IllegalArgumentException("There must be at least one converter.");
1.43 + }
1.44
1.45 - this.rateValue = rateValue;
1.46 - this.first = currencyFirst;
1.47 - this.second = currencySecond;
1.48 + for(Convertor convertor: convertors) {
1.49 + if(convertor != null) {
1.50 + convertorDelegates.addAll(convertor.convertorDelegates);
1.51 + }
1.52 + }
1.53 }
1.54
1.55 /**
1.56 @@ -38,27 +59,66 @@
1.57 notNull(amount, "amount");
1.58 notNull(fromCurrency, "fromCurrency");
1.59 notNull(toCurrency, "toCurrency");
1.60 + ConvertorDelegate appropriateDelegate = null;
1.61
1.62 - if((fromCurrency != first && fromCurrency != second) || (toCurrency != first && toCurrency != second)) {
1.63 + //try find an appropriate delegate for conversion
1.64 + for(ConvertorDelegate delegate : convertorDelegates) {
1.65 + if(delegate.isConversionSupported(fromCurrency, toCurrency)) {
1.66 + appropriateDelegate = delegate;
1.67 + break;
1.68 + }
1.69 + }
1.70 +
1.71 + if(appropriateDelegate == null) {
1.72 throw new UnsupportedConversionException(fromCurrency, toCurrency);
1.73 - }
1.74 -
1.75 - BigDecimal rateValue = getRateValue(fromCurrency, toCurrency);
1.76 - BigDecimal result = rateValue.multiply(amount);
1.77 - return new Amount(result, toCurrency);
1.78 + }
1.79 +
1.80 + return appropriateDelegate.convert(amount, fromCurrency, toCurrency);
1.81 }
1.82
1.83 - private BigDecimal getRateValue(Currency fromCurrency, Currency toCurrency) {
1.84 + /**
1.85 + * Internal delegate implements a logic for conversion between two currencies
1.86 + * and vice versa.
1.87 + * @see #isConversionSupported(Currency, Currency)
1.88 + */
1.89 + private static class ConvertorDelegate {
1.90 + private final Currency first;
1.91 + private final Currency second;
1.92 + private final BigDecimal rateValue; // a rate between the first currency and the second currency
1.93 + public static final BigDecimal one = new BigDecimal(1);
1.94
1.95 - BigDecimal retVal;
1.96 -
1.97 - if(first == fromCurrency) {
1.98 - retVal = rateValue;
1.99 - } else {
1.100 - //reverse rate
1.101 - retVal = one.divide(rateValue, 10 ,RoundingMode.HALF_UP);
1.102 + private ConvertorDelegate(BigDecimal rateValue, Currency currencyFirst, Currency currencySecond) {
1.103 + this.rateValue = rateValue;
1.104 + this.first = currencyFirst;
1.105 + this.second = currencySecond;
1.106 }
1.107
1.108 - return retVal;
1.109 + private Amount convert(BigDecimal amount, Currency fromCurrency, Currency toCurrency) throws ConversionException {
1.110 + BigDecimal rateValue = getRateValue(fromCurrency, toCurrency);
1.111 + BigDecimal result = rateValue.multiply(amount);
1.112 + return new Amount(result, toCurrency);
1.113 + }
1.114 +
1.115 + private BigDecimal getRateValue(Currency fromCurrency, Currency toCurrency) {
1.116 +
1.117 + BigDecimal retVal;
1.118 +
1.119 + if(first == fromCurrency) {
1.120 + retVal = rateValue;
1.121 + } else {
1.122 + //reverse rate
1.123 + retVal = one.divide(rateValue, 10 ,RoundingMode.HALF_UP);
1.124 + }
1.125 +
1.126 + return retVal;
1.127 + }
1.128 +
1.129 + /**
1.130 + * @return <code>true</code> if the delegate is able to convert from the given currency
1.131 + * to the given currency and vice versa otherwise <code>false</code>.
1.132 + */
1.133 + private boolean isConversionSupported(Currency fromCurrency, Currency toCurrency) {
1.134 + return ((fromCurrency == first || fromCurrency == second) && (toCurrency == first || toCurrency == second));
1.135 + }
1.136 }
1.137 }