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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package bigbank;
import java.io.ByteArrayInputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.osoa.sca.ServiceRuntimeException;
import org.osoa.sca.annotations.Reference;
import org.osoa.sca.annotations.Service;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndFeed;
/**
* @version $Rev$ $Date$
*/
@Service(ExchangeRate.class)
public class ExchangeRateImpl {
@Reference
protected CurrencyExchange exchangeRate;
private final DocumentBuilder builder;
public ExchangeRateImpl() {
try {
builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
} catch (ParserConfigurationException e) {
throw new IllegalArgumentException(e);
}
}
/**
* Retrieve the live currency exchange rate from a live feed and extract the data for a given
* currecy using XPath
* @param currency The currency
* @return The exchange rate
*/
public double getExchangeRate(String currency) {
try {
System.out.println("Retrieving exchange rate...");
// first try to get a live exchange rate quote from the RSS feed
SyndFeed feed = null;
try {
feed = exchangeRate.getRates();
// if the RSS feed isn't responding, continue with the demo using historical data
} catch (Exception e) {
System.out.println("Exchange rate live quote not available, using historical data");
return 0.74107;
}
// extract the exchange rate from the feed data
SyndEntry entry = (SyndEntry)feed.getEntries().get(0);
String rateTable = entry.getDescription().getValue();
Document doc = builder.parse(new ByteArrayInputStream(rateTable.getBytes()));
Node node = doc.getDocumentElement();
XPath path = XPathFactory.newInstance().newXPath();
XPathExpression exp = path.compile("/TABLE/TR[TD[1]='" + currency.toUpperCase() + "']/TD[2]");
Node rateNode = (Node)exp.evaluate(node, XPathConstants.NODE);
double rate = Double.valueOf(rateNode.getTextContent().trim());
System.out.println("Exchange rate: USD 1.0=" + currency + " " + rate);
return rate;
} catch (Exception e) {
throw new ServiceRuntimeException(e);
}
}
}
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