exercise 5.xmlsalesformatter.java

CMU SSD3 课程完整答案（除EXAM）

import java.util.*;

/**
 * This class implements the interface SalesFormatter. This class is implemented
 * as a singleton so a new object will not be created every time the XML format
 * is used.
 * 
 * @author Neil
 * @version 1.1.0
 * @see Order
 * @see OrderItem
 * @see Product
 */
public class XMLSalesFormatter implements SalesFormatter {

	private static XMLSalesFormatter singletonInstance = null;

	/**
	 * Static method that obtains the single instance of class
	 * XMLSalesFormatter.
	 * 
	 * @return the single instance of class XMLSalesFormatter.
	 */
	public static XMLSalesFormatter getSingletonInstance() {

		if (singletonInstance == null)
			singletonInstance = new XMLSalesFormatter();

		return singletonInstance;
	}

	/**
	 * Constructor that is declared private so it is inaccessible to other
	 * classes. A private constructor makes it impossible for any other class to
	 * create an instance of class XMLSalesFormatter.
	 */
	private XMLSalesFormatter() {

	}

	/**
	 * Produces a string that contains the specified sales information in an XML
	 * format.
	 * 
	 * @return a string that contains the specified sales information in an HTML
	 *         format.
	 */
	public String formatSales(Sales sales) {

		int k = 0;
		String result = "<Sales>\n";

		for (Iterator<Order> i = sales.iterator(); i.hasNext();) {
			Order order = i.next();
			k++;
			result += "  <Order total=\"" + order.getTotalCost() + "\">\n";

			for (Iterator<OrderItem> j = order.iterator(); j.hasNext();) {
				OrderItem orderItem = j.next();
				result += "    <OrderItem quantity=\"" + orderItem.getQuantity()
						+ "\" price=\"" + orderItem.getProduct().getPrice()
						+ "\">" + orderItem.getProduct().getCode()
						+ "</OrderItem>\n";
			}
			result += "  </Order>\n";
		}

		result += "</Sales>";
		return result;
	}
}