filecatalogloader.java

ssd3练习6的答案

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

/**
 * Creates a file catalog and loads it with data stored in a file.
 * 
 * @author Wang Yunsheng
 * @version 1.0.0
 * @see CatalogLoader
 * @see Catalog
 * @see CoffeeBrewer
 * @see Coffee
 */
public class FileCatalogLoader implements CatalogLoader {
	/* Prefix of a line with coffee data */
	private final static String COFFEE = "Coffee";

	/* Prefix of a line with coffeeBrewer data */
	private final static String COFFEEBREWER = "Brewer";

	/* Prefix of a line with product data */
	private final static String PRODUCT = "Product";

	/* Delimiter */
	private final static String DELIM = "_";

	/* Standard input stream */
	private static BufferedReader stdIn = new BufferedReader(
			new InputStreamReader(System.in));

	/* Standard output stream */
	private static PrintWriter stdOut = new PrintWriter(System.out, true);

	/* Standard error stream */
	private static PrintWriter stdErr = new PrintWriter(System.err, true);

	/**
	 * Extracts the pruduct data in the specified line and returns a
	 * {@link Product} object that encapsulates the product data.
	 * 
	 * @param line
	 *            a string that contains product data.
	 * @return a <code>Product</code> object that encapsulates the product
	 *         data in the specified line.
	 * @throws DataFormatException
	 *             if the line contains errors.
	 */
	private Product readProduct(String line) throws DataFormatException {
		StringTokenizer tokenizer = new StringTokenizer(line, DELIM);

		if (tokenizer.countTokens() != 4) {

			throw new DataFormatException(line);
		} else {

			try {

				String prefix = tokenizer.nextToken();

				return new Product(tokenizer.nextToken(),
						tokenizer.nextToken(), Double.parseDouble(tokenizer
								.nextToken()));

			} catch (NumberFormatException nfe) {

				throw new DataFormatException(line);
			}

		}

	}

	/**
	 * Extracts the coffee data in the specified line and returns a
	 * {@link Coffee} object that encapsulates the coffee data.
	 * 
	 * @param line
	 *            a string that contains coffee data.
	 * @return a <code>Coffee</code> object that encapsulates the recording
	 *         data in the specified line.
	 * @throws DataFormatException
	 *             if the line contains errors.
	 */
	private Coffee readCoffee(String line) throws DataFormatException {

		StringTokenizer tokenizer = new StringTokenizer(line, DELIM);

		if (tokenizer.countTokens() != 10) {

			throw new DataFormatException(line);
		} else {

			try {
				String prefix = tokenizer.nextToken();
				{

					return new Coffee(tokenizer.nextToken(), tokenizer
							.nextToken(), Double.parseDouble(tokenizer
							.nextToken()), tokenizer.nextToken(), tokenizer
							.nextToken(), tokenizer.nextToken(), tokenizer
							.nextToken(), tokenizer.nextToken(), tokenizer
							.nextToken());
				}

			} catch (NumberFormatException nfe) {

				throw new DataFormatException(line);
			}

		}

	}

	/**
	 * Extracts the coffeeBrewer data in the specified line and returns a
	 * {@link CoffeeBrewer} object that encapsulates the CoffeeBrewer data.
	 * 
	 * @param line
	 *            a string that contains coffeeBrewer data.
	 * @return a <code>CoffeeBrewer</code> object that encapsulates the
	 *         coffeeBrewer data in the specified line.
	 * @throws DataFormatException
	 *             if the line contains errors.
	 */
	private CoffeeBrewer readCoffeeBrewer(String line)
			throws DataFormatException {
		StringTokenizer tokenizer = new StringTokenizer(line, DELIM);

		if (tokenizer.countTokens() != 7) {

			throw new DataFormatException(line);
		} else {

			try {

				String prefix = tokenizer.nextToken();

				return new CoffeeBrewer(tokenizer.nextToken(), tokenizer
						.nextToken(),
						Double.parseDouble(tokenizer.nextToken()), tokenizer
								.nextToken(), tokenizer.nextToken(), Integer
								.parseInt(tokenizer.nextToken()));

			} catch (NumberFormatException nfe) {

				throw new DataFormatException(line);
			}

		}

	}

	/**
	 * Loads the information in the specified file into a coffee catalog and
	 * returns the catalog.
	 * 
	 * @param filename
	 *            The name of a file that contains catalog information.
	 * @return a coffee catalog.
	 * @throws IOException
	 *             if there is an error reading the information in the specified
	 *             file.
	 * @throws FileNotFoundException
	 *             if the specified file does not exist.
	 * @throws DataFormatException
	 *             if the file contains malformed data.
	 */
	public Catalog loadCatalog(String filename) throws FileNotFoundException,
			IOException, DataFormatException {

		Catalog catalog = new Catalog();

		BufferedReader reader = new BufferedReader(new FileReader(filename));
		String line = reader.readLine();

		while (line != null) {

			if (line.startsWith(COFFEE)) {
				catalog.addProduct((Product) readCoffee(line));
			} else if (line.startsWith(COFFEEBREWER)) {
				catalog.addProduct((Product) readCoffeeBrewer(line));
			} else if (line.startsWith(PRODUCT)) {
				catalog.addProduct(readProduct(line));
			} else {

				throw new DataFormatException(line);
			}

			line = reader.readLine();
		}

		reader.close();

		return catalog;
	}

}