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SalesFormatter接口

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package GourmetCoffee;

public interface SalesFormatter {
	public abstract String formatSales(Sales sales);
}

PlainTextSalesFormatter类

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package GourmetCoffee;

import java.util.ArrayList;
import java.io.*;
 
public class PlainTextSalesFormatter implements SalesFormatter{
 
	private static PlainTextSalesFormatter singletonInstance;
	
	private PlainTextSalesFormatter()
	{
		
	}
	
	public static PlainTextSalesFormatter getSingletonInstance()
	{
		
		if(singletonInstance==null) 
		{
		return singletonInstance=new PlainTextSalesFormatter();
		}
		
		return singletonInstance;
	}
	
	
	private ArrayList<String> info=new ArrayList<String>();
	public String formatSales(Sales sales)
	{
		int k=1;
		
		for(Order order:sales)
		{
			info.add("------------------------\n");
			info.add("Order "+k+"\n\n");
			for(OrderItem orderItem:order)
			{
				info.add(orderItem.getQuantity()+" "+orderItem.getProduct().getCode()+" "+orderItem.getProduct().getPrice()+"\n\n");
			}
			info.add("Total = "+order.getTotalCost()+"\n");
			k++;
			
		}
		String res="";
		for(int i=0;i<info.size();i++)
		{
			res+=info.get(i);
		}
		return res;
	}
}

HTMLSalesFormatter类

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package GourmetCoffee;
import java.util.*;
public class HTMLSalesFormatter implements SalesFormatter{
	 
	private static HTMLSalesFormatter singletonInstance;
	
	private HTMLSalesFormatter()
	{
		
	}
	public static HTMLSalesFormatter getSingletonInstance()
	{
		if(singletonInstance==null) 
		{
		return singletonInstance=new HTMLSalesFormatter();
		}
		
		return singletonInstance;
		
	}
	private ArrayList<String> output=new ArrayList<String>();
	public String formatSales(Sales sales)
	{
		output.add("<html>\n"+"  <body>\n"+"    <center><h2>Orders</h2></center>\n");
		
		for(Order order:sales)
		{
			output.add("    <hr>\n"+"    <h4>Total = "+order.getTotalCost()+"</h4>\n");
			
			for(OrderItem orderItem:order)
			{
				output.add("      <p>\n"+"        <b>code:</b> "+orderItem.getProduct().getCode()+"<br>\n");
				output.add("        <b>quantity:</b> "+orderItem.getQuantity()+"<br>\n");
				output.add("        <b>price:</b> "+orderItem.getProduct().getPrice()+"\n      </p>\n");
			}
		}
		output.add("  </body>\n"+"</html>");
		String res="";
		for(int i=0;i<output.size();i++)
		{
			res+=output.get(i);
		}
		return res;
	}
}

XMLSalesFormatter类

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package GourmetCoffee;
import java.util.ArrayList;
public class XMLSalesFormatter implements SalesFormatter{
	
	private static XMLSalesFormatter singletonInstance;
	
	private XMLSalesFormatter()
	{
		
	}
	public static XMLSalesFormatter getSingletonInstance()
	{
		if(singletonInstance==null) 
		{
		return singletonInstance=new XMLSalesFormatter();
		}
		
		return singletonInstance;
	}
	private ArrayList<String> output=new ArrayList<String>();
	public String formatSales(Sales sales) {
		output.add("<Sales>\n");
		for(Order order: sales)
		{
			output.add("  <Order total=\""+ order.getTotalCost()+"\">\n");
			for(OrderItem orderitem: order)
			{
				output.add("    <OrderItem quantity=\""+ orderitem.getQuantity()+"\" price=\""+orderitem.getProduct()+"\">code1</OrderItem>\n");
			}
			output.add("  </Order>\n");
		}
		output.add("</Sales>\n");
		String res = "" ;
		for(int i=0;i<output.size();i++) {
			res+=output.get(i);
		}
		return res;
	}
}

GourmetCoffee类

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package GourmetCoffee;
import java.io.*;
import java.util.*;
//import java.text.*;

/**
 * This class implements a gourmet coffee system.
 *
 * @author author name
 * @version 1.1.0
 * @see Product
 * @see Coffee
 * @see CoffeeBrewer
 * @see Catalog
 * @see OrderItem
 * @see Order
 * @see SalesFormatter
 * @see PlainTextSalesFormatter
 * @see HTMLSalesFormatter
 * @see XMLSalesFormatter
 */
public class GourmetCoffee  {

	private static BufferedReader  stdIn =
		new  BufferedReader(new  InputStreamReader(System.in));
	private static PrintWriter  stdOut = new  PrintWriter(System.out, true);
	private static PrintWriter  stdErr = new  PrintWriter(System.err, true);

	private Sales  sales;

	private SalesFormatter  salesFormatter;

	/**
	 * Loads data into the catalog and starts the application.
	 *
	 * @param args  String arguments.  Not used.
	 * @throws IOException if there are errors in the input.
	 */
	public static void  main(String[]  args) throws IOException  {

		GourmetCoffee  application = new  GourmetCoffee();
		application.run();

	}

	/**
	 * Constructs a <code>GourmetCoffee</code> object and
	 * initializes the catalog and sales data.
	 *
	 * @param initialCatalog a product catalog
	 */
	private GourmetCoffee() {

		this.sales = new Sales();
		this.salesFormatter = 
			PlainTextSalesFormatter.getSingletonInstance();

		loadSales(loadCatalog());
	}

	/**
	 * Creates an empty catalog and then add products to it.
	 *
	 * @return a product catalog
	 */
	private Catalog loadCatalog() {

		Catalog catalog = new Catalog();

		catalog.addProduct(
			new Coffee("C001", "Colombia, Whole, 1 lb", 17.99,
				"Colombia", "Medium", "Rich and Hearty", "Rich",
				"Medium", "Full"));
		catalog.addProduct(
			new Coffee("C002", "Colombia, Ground, 1 lb", 18.75,
				"Colombia", "Medium", "Rich and Hearty", "Rich",
				"Medium","Full"));
		catalog.addProduct(
			new Coffee("C003", "Italian Roasts, Whole, 1 lb",
				16.80, "Latin American Blend", "Italian Roast",
				"Dark and heavy", "Intense", "Low", "Medium"));
		catalog.addProduct(
			new Coffee("C004", "Italian Roasts, Ground, 1 lb",
				17.55, "Latin American Blend", "Italian Roast",
				"Dark and heavy", "Intense", "Low", "Medium"));
		catalog.addProduct(
			new Coffee("C005", "French Roasts, Whole, 1 lb",
				16.80, "Latin American Blend", "French Roast",
				"Bittersweet, full intense", "Intense, full", "None", "Medium"));
		catalog.addProduct(
			new Coffee("C006", "French Roasts, Ground, 1 lb",
				17.55, "Latin American Blend", "French Roast",
				"Bittersweet, full intense", "Intense, full", "None", "Medium"));
		catalog.addProduct(
			new Coffee("C007", "Guatemala, Ground, 1 lb", 17.99,
				"Guatemala", "Medium", "Rich and complex", "Spicy",
				"Medium to high", "Medium to full"));
		catalog.addProduct(
			new Coffee("C008", "Guatemala, Ground, 1 lb", 18.75,
				"Guatemala", "Medium", "Rich and complex", "Spicy",
				"Medium to high", "Medium to full"));
		catalog.addProduct(
			new Coffee("C009", "Guatemala, Whole, 1 lb", 19.99,
				"Sumatra", "Medium", "Vibrant and powdery",
				"Like dark chocolate", "Gentle", "Rich and full"));
		catalog.addProduct(
			new Coffee("C010", "Guatemala, Ground, 1 lb", 20.50,
				"Sumatra", "Medium", "Vibrant and powdery",
				"Like dark chocolate", "Gentle", "Rich and full"));
		catalog.addProduct(
			new Coffee("C011", "Special Blend, Whole, 1 lb",
				16.80, "Latin American Blend", "Dark roast",
				"Full, roasted flavor", "Hearty", "Bold and rich", "Full"));
		catalog.addProduct(
			new Coffee("C012", "Special Blend, Ground, 1 lb",
				17.55, "Latin American Blend", "Dark roast",
				"Full, roasted flavor", "Hearty", "Bold and rich", "Full"));

		catalog.addProduct(
			new CoffeeBrewer("B001", "Home Coffee Brewer",
				150.00, "Brewer 100", "Pourover", 6));
		catalog.addProduct(
			new CoffeeBrewer("B002", "Coffee Brewer, 2 Warmers",
				200.00, "Brewer 200", "Pourover", 12));
		catalog.addProduct(
			new CoffeeBrewer("B003", "Coffee Brewer, 3 Warmers",
				280.00, "Brewer 210", "Pourover", 12));
		catalog.addProduct(
			new CoffeeBrewer("B004", "Commercial Brewer, 20 cups",
				380.00, "Quick Coffee 100", "Automatic", 20));
		catalog.addProduct(
			new CoffeeBrewer("B005", "Commercial Brewer, 40 cups",
				480.00, "Quick Coffee 200", "Automatic", 40));

		catalog.addProduct(
			new Product("A001", "Almond Flavored Syrup", 9.00));
		catalog.addProduct(
			new Product("A002", "Irish Creme Flavored Syrup", 9.00));
		catalog.addProduct(
			new Product("A003", "Mint Flavored syrup", 9.00));
		catalog.addProduct(
			new Product("A004", "Caramel Flavored Syrup", 9.00));
		catalog.addProduct(
			new Product("A005", "Gourmet Coffee Cookies", 12.00));
		catalog.addProduct(
			new Product("A006", "Gourmet Coffee Travel Thermo", 18.00));
		catalog.addProduct(
			new Product("A007", "Gourmet Coffee Ceramic Mug", 8.00));
		catalog.addProduct(
			new Product("A008", "Gourmet Coffee 12 Filters", 15.00));
		catalog.addProduct(
			new Product("A009", "Gourmet Coffee 36 Filters", 45.00));

		return catalog;
	}

	/**
	 * Initializes the sales object.
	 */
	private void loadSales(Catalog catalog) {

		Order orderOne = new Order();

		orderOne.addItem(new OrderItem(catalog.getProduct("C001"), 5));
		this.sales.addOrder(orderOne);

		Order orderTwo = new Order();

		orderTwo.addItem(new OrderItem(catalog.getProduct("C002"), 2));
		orderTwo.addItem(new OrderItem(catalog.getProduct("A001"), 2));
		this.sales.addOrder(orderTwo);

		Order orderThree = new Order();

		orderThree.addItem(new OrderItem(catalog.getProduct("B002"), 1));
		this.sales.addOrder(orderThree);
	}

	/**
	 * Displays a menu of options and verifies the user's choice.
	 *
	 * @return an integer in the range [0,3]
	 */
	private int  getChoice() throws IOException  {

		int  input;

		do  {
			try  {
				stdErr.println();
				stdErr.print("[0]  Quit\n"
				             + "[1]  Display sales (Plain Text)\n"
				             + "[2]  Display sales (HTML)\n"
				             + "[3]  Display sales (XML)\n"
				             + "choice> ");
				stdErr.flush();

				input = Integer.parseInt(stdIn.readLine());

				stdErr.println();

				if (0 <= input && 3 >= input)  {
					break;
				} else {
					stdErr.println("Invalid choice:  " + input);
				}
			} catch (NumberFormatException  nfe)  {
				stdErr.println(nfe);
			}
		}  while (true);

		return  input;
	}

	/**
	 * Changes the sales formatter.
	 *
	 * @param newFormatter a sales formatter
	 */
	private void setSalesFormatter(SalesFormatter newFormatter){
		this.salesFormatter = newFormatter;
	}

	/**
	 * Displays the sales information in the current format.
	 */
	private void displaySales() {
		System.out.println(this.salesFormatter.formatSales(sales));
	}

	/**
	 * Presents the user with a menu of options and executes the
	 * selected task.
	 */
	private void run() throws IOException  {

		int  choice = getChoice();

		while (choice != 0)  {

			if (choice == 1)  {

				this.setSalesFormatter(PlainTextSalesFormatter.getSingletonInstance());
				this.displaySales();

			} else if (choice == 2)  {

				this.setSalesFormatter(HTMLSalesFormatter.getSingletonInstance());
				this.displaySales();

			} else if (choice == 3)  {

				this.setSalesFormatter(XMLSalesFormatter.getSingletonInstance());
				this.displaySales();
			}

			choice = getChoice();
		}
	}
}

注意事项

接口的继承及重写

在GourmetCoffee类中通过setSalesFormatter()改写本类中的salesFormatter，通过formatSales实现多态