1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/task2/solution10/src/org/apidesign/apifest08/currency/OfflineConverterProvider.java	Wed Oct 01 10:43:05 2008 +0200
     1.3 @@ -0,0 +1,120 @@
     1.4 +package org.apidesign.apifest08.currency;
     1.5 +
     1.6 +import java.util.*;
     1.7 +
     1.8 +/**
     1.9 + * ConvertorProvider class is introduced to handle
    1.10 + */
    1.11 +public final class OfflineConverterProvider implements CurrencyConverterProvider {
    1.12 +
    1.13 +
    1.14 +	// we can't synchronize on DEFAULT as it's not final and can even be null in synchronized section
    1.15 +	private static final Object LOCK = new Object();
    1.16 +	private static CurrencyConverterProvider DEFAULT;
    1.17 +
    1.18 +	// this is not nice and could be static, but future usage is uncertain and it's pretty easy to create
    1.19 +	private final Map<Currency, Double> rates;
    1.20 +
    1.21 +	private OfflineConverterProvider() {
    1.22 +		rates = new HashMap<Currency, Double>();
    1.23 +		// simple initialization just for Task1Test
    1.24 +		rates.put(Currency.getInstance("USD"), 100.0);
    1.25 +		rates.put(Currency.getInstance("CZK"), 1700.0);
    1.26 +		rates.put(Currency.getInstance("SKK"), 2125.0);
    1.27 +	}
    1.28 +
    1.29 +	/**
    1.30 +	 * Provides default implementation of ConvertorProvider. This Converter does nos not ensure accuracy
    1.31 +	 * of exchange rates, but should be functional at any circumstances including being offline.
    1.32 +	 *
    1.33 +	 * @return
    1.34 +	 */
    1.35 +	public static CurrencyConverterProvider getInstance() {
    1.36 +		// should be necessary in current implementation as creating CurrencyConverterProvider is cheap, but for future
    1.37 +		if (DEFAULT == null)
    1.38 +			synchronized (LOCK) {
    1.39 +				if (DEFAULT == null)
    1.40 +					DEFAULT = new OfflineConverterProvider();
    1.41 +			}
    1.42 +		return DEFAULT;
    1.43 +	}
    1.44 +
    1.45 +	@Override
    1.46 +	public CurrencyConverter getConverter(double amount1, /*@NotNull*/ String currency1,
    1.47 +									   double amount2, /*@NotNull*/ String currency2)
    1.48 +			throws IllegalArgumentException {
    1.49 +
    1.50 +		return getConverter(amount1, Currency.getInstance(currency2), amount2, Currency.getInstance(currency1));
    1.51 +	}
    1.52 +
    1.53 +	/**
    1.54 +	 * Retrieves converter that is capable of converting values between currency1 and currency2. The exchange is
    1.55 +	 * specified in easy to understand way. By specifying values in two currencies that are equal. For example
    1.56 +	 * CurrencyConverter.getConverter(25, "CZK", 1, "EUR"); means 25CKZ is equal to 1EUR. This enables user to
    1.57 +	 * use this method without having to calculate anything. In general this can be expressed by formula
    1.58 +	 * amount1[currency1] = amount2[currency2].
    1.59 +	 *
    1.60 +	 * @param amount1
    1.61 +	 * @param currency1
    1.62 +	 * @param amount2
    1.63 +	 * @param currency2
    1.64 +	 *
    1.65 +	 * @return
    1.66 +	 *
    1.67 +	 * @throws IllegalArgumentException
    1.68 +	 * @throws CurrencyNotAvailableException
    1.69 +	 *
    1.70 +	 */
    1.71 +	@Override
    1.72 +	public CurrencyConverter getConverter(double amount1, /*@NotNull*/ Currency currency1,
    1.73 +									   double amount2, /*@NotNull*/ Currency currency2)
    1.74 +			throws IllegalArgumentException, CurrencyNotAvailableException {
    1.75 +		if (amount1 <= 0.0 || amount2 <= 0.0)
    1.76 +			throw new IllegalArgumentException(
    1.77 +					String.format("The specified currency values (%1$s, %2$s)", amount1, amount2));
    1.78 +		return new ConstantRateConverter(currency2, currency1, amount2 / amount1);
    1.79 +	}
    1.80 +
    1.81 +	/**
    1.82 +	 * Creates a new converter that is able to convert between all specified currencies.
    1.83 +	 *
    1.84 +	 * @param currencies that the converter should be created for
    1.85 +	 *
    1.86 +	 * @return converter able to convert between all specified currencies
    1.87 +	 *
    1.88 +	 * @throws CurrencyNotAvailableException
    1.89 +	 *          thrown when one of the currencies is not available
    1.90 +	 */
    1.91 +	@Override
    1.92 +	public CurrencyConverter getConverter(/*@NotNull*/ Currency... currencies) throws CurrencyNotAvailableException {
    1.93 +		for (Currency c : currencies) {
    1.94 +			if (c == null)
    1.95 +				throw new NullPointerException("One of the specified currencies is null");
    1.96 +			if (!rates.containsKey(c))
    1.97 +				throw new CurrencyNotAvailableException(c);
    1.98 +		}
    1.99 +		return new MultiCurrencyConstantRateConverter(rates);
   1.100 +	}
   1.101 +
   1.102 +	/**
   1.103 +	 * Creates a new converter that is able to convert between all specified currencies.
   1.104 +	 *
   1.105 +	 * @param currencies that the converter should be created for
   1.106 +	 *
   1.107 +	 * @return converter able to convert between all specified currencies
   1.108 +	 *
   1.109 +	 * @throws CurrencyNotAvailableException
   1.110 +	 *                                  thrown when one of the currencies is not available
   1.111 +	 * @throws NullPointerException	 if any of the specified currencies is null
   1.112 +	 * @throws IllegalArgumentException if any of the specified currencies is not a valid ISO code
   1.113 +	 */
   1.114 +	@Override
   1.115 +	public CurrencyConverter getConverter(/*@NotNull*/ String... currencies)
   1.116 +			throws CurrencyNotAvailableException, IllegalArgumentException, NullPointerException {
   1.117 +
   1.118 +		Currency[] c2 = new Currency[currencies.length];
   1.119 +		for (int i = 0; i < c2.length; i++)
   1.120 +			c2[i] = Currency.getInstance(currencies[i]);
   1.121 +		return getConverter(c2);
   1.122 +	}
   1.123 +}