1.1 --- a/task3/solution06/src/org/apidesign/apifest08/currency/Convertor.java	Tue Oct 07 11:05:34 2008 +0200
     1.2 +++ b/task3/solution06/src/org/apidesign/apifest08/currency/Convertor.java	Fri Oct 10 21:54:39 2008 +0200
     1.3 @@ -8,6 +8,9 @@
     1.4  import java.util.Currency;
     1.5  import java.util.List;
     1.6  
     1.7 +/**
     1.8 + * Currency covertor.
     1.9 + */
    1.10  public final class Convertor {
    1.11  	
    1.12  	private List<ConvertorDelegate> convertorDelegates = new ArrayList<ConvertorDelegate>();
    1.13 @@ -24,7 +27,22 @@
    1.14  		notNull(currencyFirst, "currencyFirst");
    1.15  		notNull(currencySecond, "currencySecond");		
    1.16  		notNull(rateValue, "rateValue");	
    1.17 -		convertorDelegates.add(new ConvertorDelegate(rateValue, currencyFirst, currencySecond));
    1.18 +		convertorDelegates.add(new ConvertorDelegate(new StaticRateProvider(rateValue), currencyFirst, currencySecond));
    1.19 +	}
    1.20 +	
    1.21 +	/**
    1.22 +	 * Create new instance of the converter for the given currencies and its rate. 
    1.23 +	 * A rate value is provided by {@link RateProvider}.
    1.24 +	 * 
    1.25 +	 * @param rateProvider the rate provider
    1.26 +	 * @param currencyFirst the first currency
    1.27 +	 * @param currencySecond the second currency
    1.28 +	 */
    1.29 +	public Convertor(RateProvider rateProvider, Currency currencyFirst, Currency currencySecond) {
    1.30 +		notNull(currencyFirst, "currencyFirst");
    1.31 +		notNull(currencySecond, "currencySecond");		
    1.32 +		notNull(rateProvider, "rateProvider");
    1.33 +		convertorDelegates.add(new ConvertorDelegate(rateProvider, currencyFirst, currencySecond));
    1.34  	}
    1.35  	
    1.36  	/**
    1.37 @@ -84,11 +102,12 @@
    1.38  	private static class ConvertorDelegate {
    1.39  		private final Currency first;
    1.40  		private final Currency second;
    1.41 -		private final BigDecimal rateValue; // a rate between the first currency and the second currency
    1.42 +		private final RateProvider rateProvider;
    1.43  		public static final BigDecimal one = new BigDecimal(1);
    1.44  		
    1.45 -		private ConvertorDelegate(BigDecimal rateValue, Currency currencyFirst, Currency currencySecond) {
    1.46 -			this.rateValue = rateValue;
    1.47 +		
    1.48 +		private ConvertorDelegate(RateProvider rateProvider, Currency currencyFirst, Currency currencySecond) {
    1.49 +			this.rateProvider = rateProvider;
    1.50  			this.first = currencyFirst;
    1.51  			this.second = currencySecond;
    1.52  		}
    1.53 @@ -104,8 +123,16 @@
    1.54  			BigDecimal retVal;
    1.55  			
    1.56  			if(first == fromCurrency) {
    1.57 +				BigDecimal rateValue = rateProvider.getRate();
    1.58 +				if(rateValue == null) {
    1.59 +					throw new NullPointerException("Rate cannot be null!");
    1.60 +				}
    1.61  				retVal = rateValue;
    1.62  			} else {	
    1.63 +				BigDecimal rateValue = rateProvider.getRate();
    1.64 +				if(rateValue == null) {
    1.65 +					throw new NullPointerException("Rate cannot be null!");
    1.66 +				}
    1.67  				//reverse rate	
    1.68  				retVal = one.divide(rateValue, 10 ,RoundingMode.HALF_UP);
    1.69  			}
    1.70 @@ -121,4 +148,29 @@
    1.71  			return ((fromCurrency == first || fromCurrency == second) && (toCurrency == first || toCurrency == second));
    1.72  		}
    1.73  	}
    1.74 +	
    1.75 +	/**
    1.76 +	 * A rate provider. This class represents a way how could be "static" convertor
    1.77 +	 * extended in order converts according to current rate.
    1.78 +	 */
    1.79 +	public static abstract class RateProvider { 
    1.80 +		
    1.81 +		/**
    1.82 +		 * @return a rate between the from currency and the to currency associated with
    1.83 +		 * a given convertor.
    1.84 +		 */
    1.85 +		public abstract BigDecimal getRate();
    1.86 +	}
    1.87 +	
    1.88 +	private static class StaticRateProvider extends RateProvider{
    1.89 +		private final BigDecimal rateValue;
    1.90 +		
    1.91 +		private StaticRateProvider(BigDecimal rateValue){
    1.92 +			this.rateValue = rateValue;
    1.93 +		}
    1.94 +		
    1.95 +		public BigDecimal getRate() {
    1.96 +			return this.rateValue;
    1.97 +		}
    1.98 +	}
    1.99  }