Java tutorial
/* * Copyright (c) 2012 Brown Bag Consulting. * This file is part of the ExpressUI project. * Author: Juan Osuna * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License Version 3 * as published by the Free Software Foundation with the addition of the * following permission added to Section 15 as permitted in Section 7(a): * FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY * Brown Bag Consulting, Brown Bag Consulting DISCLAIMS THE WARRANTY OF * NON INFRINGEMENT OF THIRD PARTY RIGHTS. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. * * The interactive user interfaces in modified source and object code versions * of this program must display Appropriate Legal Notices, as required under * Section 5 of the GNU Affero General Public License. * * You can be released from the requirements of the license by purchasing * a commercial license. Buying such a license is mandatory as soon as you * develop commercial activities involving the ExpressUI software without * disclosing the source code of your own applications. These activities * include: offering paid services to customers as an ASP, providing * services from a web application, shipping ExpressUI with a closed * source product. * * For more information, please contact Brown Bag Consulting at this * address: juan@brownbagconsulting.com. */ package com.expressui.domain.ecbfx; import com.expressui.domain.RestClientService; import org.apache.commons.lang.time.DateUtils; import org.joda.money.CurrencyUnit; import org.joda.money.IllegalCurrencyException; import org.joda.money.Money; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.stereotype.Service; import javax.annotation.Resource; import javax.ws.rs.GET; import javax.ws.rs.Produces; import javax.xml.bind.annotation.*; import java.math.BigDecimal; import java.math.RoundingMode; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.*; /** * Service for fetching currency exchange rates from European Central Bank. * See http://www.ecb.int/stats/eurofxref/eurofxref-daily.xml */ @Configuration @Service public class EcbfxService extends RestClientService { private static final DateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd"); private Date rateDay; private Date fetchDay; private Map<String, BigDecimal> rates; @Resource private ECBFXClient ecbfxClient; public BigDecimal convert(BigDecimal amount, String sourceCurrencyCode, String targetCurrencyCode) throws IllegalCurrencyException { if (sourceCurrencyCode.equals(targetCurrencyCode)) return amount; Map<String, BigDecimal> rates = getFXRates(); BigDecimal inverseRate = rates.get(sourceCurrencyCode); if (inverseRate == null) throw new IllegalCurrencyException("Unknown currency: " + sourceCurrencyCode); BigDecimal sourceRate = new BigDecimal(1).divide(inverseRate, 10, RoundingMode.HALF_EVEN); CurrencyUnit sourceCurrencyUnit = CurrencyUnit.of(sourceCurrencyCode); Money amountInSourceCurrency = Money.of(sourceCurrencyUnit, amount, RoundingMode.HALF_EVEN); Money amountInEuros; if (sourceCurrencyUnit.getCurrencyCode().equals("EUR")) { amountInEuros = amountInSourceCurrency; } else { amountInEuros = amountInSourceCurrency.convertedTo(CurrencyUnit.of("EUR"), sourceRate, RoundingMode.HALF_EVEN); } BigDecimal targetRate = rates.get(targetCurrencyCode); if (targetRate == null) throw new IllegalCurrencyException("Unknown currency: " + targetCurrencyCode); Money amountInTargetCurrency = amountInEuros.convertedTo(CurrencyUnit.of(targetCurrencyCode), targetRate, RoundingMode.HALF_EVEN); return amountInTargetCurrency.getAmount(); } public Map<String, BigDecimal> getFXRates() { if (rateDay == null || (DateUtils.truncatedCompareTo(rateDay, new Date(), Calendar.DAY_OF_MONTH) < 0 && DateUtils.truncatedCompareTo(fetchDay, new Date(), Calendar.DAY_OF_MONTH) < 0)) { fetchFXRates(); } return rates; } private void fetchFXRates() { rates = new HashMap<String, BigDecimal>(); ECBFXResponse ecbfxResponse = ecbfxClient.getFXRates(); try { rateDay = DATE_FORMAT.parse(ecbfxResponse.mainCube.quoteDate.time); fetchDay = DateUtils.truncate(new Date(), Calendar.DAY_OF_MONTH); } catch (ParseException e) { throw new RuntimeException(e); } for (ECBFXResponse.MainCube.QuoteDate.Rate rate : ecbfxResponse.mainCube.quoteDate.rates) { rates.put(rate.currency, new BigDecimal(rate.rate)); } rates.put("EUR", new BigDecimal(1)); } @Bean ECBFXClient getEcbfxClient(@Value("${ecbfxService.url:}") String url) throws Exception { return create(url, ECBFXClient.class); } static interface ECBFXClient { @GET @Produces("application/xml") ECBFXResponse getFXRates(); } private static final String NAMESPACE = "http://www.ecb.int/vocabulary/2002-08-01/eurofxref"; @XmlRootElement(namespace = "http://www.gesmes.org/xml/2002-08-01", name = "Envelope") @XmlAccessorType(XmlAccessType.FIELD) static class ECBFXResponse { @XmlElement(name = "Cube", namespace = NAMESPACE) public MainCube mainCube; @XmlAccessorType(XmlAccessType.FIELD) public static class MainCube { @XmlElement(name = "Cube", namespace = NAMESPACE) public QuoteDate quoteDate; @XmlAccessorType(XmlAccessType.FIELD) public static class QuoteDate { @XmlAttribute public String time; @XmlElement(name = "Cube", namespace = NAMESPACE) public List<Rate> rates; @XmlAccessorType(XmlAccessType.FIELD) public static class Rate { @XmlAttribute public String currency; @XmlAttribute public String rate; } } } } }