exercise 6.filecatalogloader.java

CMU SSD3 课程完整答案（除EXAM）

import java.io.*;
import java.util.*;

/**
 * The class FileCatalogLoader implements interface CatalogLoader. It is used to
 * obtain a product catalog from a file.
 * 
 * @author Neil
 * @version 1.1.0
 * @see CatalogLoader
 * @see Product
 * @see Coffee
 * @see CoffeeBrewer
 */
public class FileCatalogLoader implements CatalogLoader {

	/**
	 * This method reads a line of coffee-accessory data. It uses the class
	 * StringTokenizer to extract the accessory data in the specified line. If
	 * the line is error free, this method returns a Product object that
	 * encapsulates the accessory data. If the line has errors, that is, if it
	 * does not have the expected number of tokens or the token that should
	 * contain a double does not; this method throws a DataFormatException that
	 * contains the line of malformed data.
	 * 
	 * @param line
	 *            a line of coffee-accessory data.
	 * @return a Product object that encapsulates the accessory data.
	 * @throws DataFormatException
	 *             a DataFormatException that contains the line of malformed
	 *             data.
	 */
	private Product readProduct(String line) throws DataFormatException {

		StringTokenizer tknzr = new StringTokenizer(line, "_");

		String code;
		String description;
		double price;

		tknzr.nextToken();

		code = tknzr.nextToken();
		description = tknzr.nextToken();
		price = Double.parseDouble(tknzr.nextToken());

		return new Product(code, description, price);
	}

	/**
	 * This method reads a line of coffee data. It uses the class
	 * StringTokenizer to extract the coffee data in the specified line. If the
	 * line is error free, this method returns a Coffee object that encapsulates
	 * the coffee data. If the line has errors, that is, if it does not have the
	 * expected number of tokens or the token that should contain a double does
	 * not; this method throws a DataFormatException that contains the line of
	 * malformed data.
	 * 
	 * @param line
	 *            a line of coffee data.
	 * @return a Coffee object that encapsulates the coffee data.
	 * @throws DataFormatException
	 *             a DataFormatException that contains the line of malformed
	 *             data.
	 */
	private Coffee readCoffee(String line) throws DataFormatException {

		StringTokenizer tknzr = new StringTokenizer(line, "_");

		String code;
		String description;
		double price;
		String origin;
		String roast;
		String flavor;
		String aroma;
		String acidity;
		String body;

		tknzr.nextToken();

		code = tknzr.nextToken();
		description = tknzr.nextToken();
		price = Double.parseDouble(tknzr.nextToken());
		origin = tknzr.nextToken();
		roast = tknzr.nextToken();
		flavor = tknzr.nextToken();
		aroma = tknzr.nextToken();
		acidity = tknzr.nextToken();
		body = tknzr.nextToken();

		return new Coffee(code, description, price, origin, roast, flavor,
				aroma, acidity, body);
	}

	/**
	 * This method reads a line of coffee-brewer data. It uses the class
	 * StringTokenizer to extract the brewer data in the specified line. If the
	 * line is error free, this method returns a CoffeeBrewer object that
	 * encapsulates the brewer data. If the line has errors, that is, if it does
	 * not have the expected number of tokens or the tokens that should contain
	 * a number do not; this method throws a DataFormatException that contains
	 * the line of malformed data.
	 * 
	 * @param line
	 *            a line of coffee-brewer data.
	 * @return a CoffeeBrewer object that encapsulates the brewer data.
	 * @throws DataFormatException
	 *             a DataFormatException that contains the line of malformed
	 *             data.
	 */
	private CoffeeBrewer readCoffeeBrewer(String line)
			throws DataFormatException {

		StringTokenizer tknzr = new StringTokenizer(line, "_");

		String code;
		String description;
		double price;
		String model;
		String waterSupply;
		int numberOfCups;

		tknzr.nextToken();

		code = tknzr.nextToken();
		description = tknzr.nextToken();
		price = Double.parseDouble(tknzr.nextToken());
		model = tknzr.nextToken();
		waterSupply = tknzr.nextToken();
		numberOfCups = Integer.parseInt(tknzr.nextToken());

		return new CoffeeBrewer(code, description, price, model, waterSupply,
				numberOfCups);
	}

	/**
	 * Loads the product catalog with the data in the specified file.
	 * 
	 * @param filename
	 *            The name of a file that contains catalog information.
	 * @return the product catalog.
	 * @throws FileNotFoundException
	 *             if the specified file does not exist.
	 * @throws IOException
	 *             if there is an error reading the information in the specified
	 *             file.
	 * @throws DataFormatException
	 *             if the file contains badly-formed data.
	 */
	public Catalog loadCatalog(String fileName) throws FileNotFoundException,
			IOException, DataFormatException {

		Catalog result = new Catalog();
		BufferedReader fileIn = new BufferedReader(new FileReader(fileName));

		String line = fileIn.readLine();

		while (line != null) {
			StringTokenizer tknzr = new StringTokenizer(line, "_");
			String type = tknzr.nextToken();

			if (type.equals("Coffee"))
				result.addProduct((readCoffee(line)));
			if (type.equals("Brewer"))
				result.addProduct(readCoffeeBrewer(line));
			if (type.equals("Product"))
				result.addProduct(readProduct(line));

			line = fileIn.readLine();
		}

		fileIn.close();
		return result;
	}
}