filecatalogloader.java

ssd3 exercise6正确的

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


public class FileCatalogLoader implements CatalogLoader  
{
	private final static String PRODUCT__PREFIX = "Product";
    
	private final static String COFFEE__PREFIX= "Coffee";
	 
	private final static String  BREWER__PREFIX= "Brewer";
	private final static String DELIM = "_";


	public Catalog loadCatalog (String filename) throws IOException,
		FileNotFoundException, DataFormatException 
	{

		Catalog catalog = new Catalog();

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

		while (line != null) 
		{

			Product product = null;


			if (line.startsWith( PRODUCT__PREFIX)) 
			{
				product = readProduct(line);
			} 
			else if (line.startsWith( COFFEE__PREFIX)) 
			{
				product = readCoffee(line);
			} 
			else if(line.startsWith(  BREWER__PREFIX))
			{
				product= readCoffeeBrewer(line);
			}
			else 
			{

				throw new DataFormatException(line);
			}

			catalog.addProduct(product);

			line =  reader.readLine();
		}

		return catalog;
	}

	/**
	 * @param line
	 * @return
	 */
	

	/**
	 * Extracts the book data in the specified line and returns
	 * a {@link Book} object that encapsulates the book data.
	 *
	 * @param line  a string that contains book data.
	 * @return  a <code>Book</code> object that encapsulates the
	 *          book 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 recording data in the specified line and returns
	 * a {@link Recording} object that encapsulates the book data.
	 *
	 * @param line  a string that contains recording data.
	 * @return  a <code>Recording</code> object that encapsulates the
	 *          recording 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);
			}
		}
	}
	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);
			}
		}
	}

}