filecatalogloader.java

CMU_ ssd3_第三单元答案 绝对正确

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

/**
 * This class is used to obtain a product catalog from a file.
 *
 * @author LT
 * @version 1.0.0
 * @see CatalogLoader
 * created on 2006-11-25
 */
public class FileCatalogLoader 
				implements CatalogLoader {
	
	/*Prefix of a line with coffee data*/
	private final static String COFFEE_PREFIX = "Coffee";
	
	/*Prefix of a line with coffee brewer data*/
	private final static String BREWER_PREFIX = "Brewer";
	
	/*Prefix of a line with product data*/
	private final static String PRODUCT_PREFIX= "Product";
	
	/*The string tokenizer*/
	private static StringTokenizer tokenizer;
	
	/*The specified tokenizer*/
	private static String TOKENIZER = "_";
	
	/**
	 * Returns a {@link @Product} object that encapsulates the 
	 * 		   accessory data in the specified line.
	 * 
	 * @param line The line with the accessory data of Product.
	 * @return a Product object that encapsulates the 
	 * 		   accessory data  in the specified line.
	 * @throws DataFormatException 
	 * 		   if it does not have the expected number of tokens 
	 * 		   or the token that should contain a double does not.
	 */
	private Product readProduct(String line)
    				throws DataFormatException {
		
		String code = "",
		       description = "";

		double price = 0.0;
		
		if( tokenizer.countTokens() != 3 ) {
			
			throw new DataFormatException( line );
			
		} else {
			try {
					code = tokenizer.nextToken();
					description = tokenizer.nextToken();
					price = Double.parseDouble( tokenizer.nextToken() );
		
					Product product = new Product( code, description, price );
		
					return product;
			} catch( NumberFormatException dfe ) {
				
				throw new DataFormatException( line );
			}
		}
	}
	
	/**
	 * Returns a {@link @Coffee} object that encapsulates the 
	 * 		   coffee data in the specified line.
	 * 
	 * @param line The line with the data of Coffee.
	 * @return a {@link Coffee} object that encapsulates the 
	 * 		   coffee data in the specified line.
	 * @throws DataFormatException 
	 * 		   if it does not have the expected number of tokens 
	 * 		   or the token that should contain a double does not.
	 */
	private Coffee readCoffee(String line)
    				throws DataFormatException {
		
		String code = "",
		       description = "",
		       origin = "",
		       roast  = "",
		       flavor = "",
		       aroma  = "",
		       acidity= "",
		       body   = "";
		
		double price = 0.0;
		
		if( tokenizer.countTokens() != 8 ) {
			
			throw new DataFormatException( line );
		} else {
			try {
					code = tokenizer.nextToken();
					description = tokenizer.nextToken();
					price = Double.parseDouble( tokenizer.nextToken() );
					origin = tokenizer.nextToken();
					roast  = tokenizer.nextToken();
					flavor = tokenizer.nextToken();
					aroma  = tokenizer.nextToken();
					acidity= tokenizer.nextToken();
					body   = tokenizer.nextToken();
		
					Coffee coffee = new Coffee(code,description,price,
								   origin,roast, flavor,
								   aroma, acidity, body);
		
					return coffee;
					
			} catch(NumberFormatException nfe) {
				
				throw new DataFormatException( line );
			}
		}
    }

	/**
	 * Returns a {@link @CoffeeBrewer} object that encapsulates the 
	 * 		   brewer data
	 * 
	 * @param line The line with the data of Coffee Brewer.
	 * @return a {@link CoffeeBrewer} object that encapsulates the 
	 * 		   brewer data
	 * @throws DataFormatException
	 * 		   if it does not have the expected number of tokens 
	 * 		   or the token that should contain a double does not.
	 */
	private CoffeeBrewer readCoffeeBrewer(String line) 
    				throws DataFormatException {
		
		String code  = "",
		       description = "",
		       model = "",
		       waterSupply ="";
		
		double price = 0.0;	   
		int numberOfCups = 0;
		
		if( tokenizer.countTokens() != 4 ) {
			
			throw new DataFormatException( line );
		} else {
			try {
					code = tokenizer.nextToken();
					description = tokenizer.nextToken();
					price = Double.parseDouble( tokenizer.nextToken() );
					model = tokenizer.nextToken();
					waterSupply = tokenizer.nextToken();
					numberOfCups = Integer.parseInt( tokenizer.nextToken() );
		
					CoffeeBrewer coffeeBrewer = 
								new CoffeeBrewer( code, description, price,
										  model,waterSupply,numberOfCups );
		
					return coffeeBrewer;
		
			} catch(NumberFormatException nfe) {
				
				throw new DataFormatException( line );
			}
		}
	}
	
	/**
	 * Returns A {@link @Catalog} object that contains the information
	 * 		   in the specified file.
	 * 
	 * @param filename The file that contains the information.
	 * @return A {@link @Catalog} object that contains the information
	 * 		   in the specified file.
	 * @throws FileNotFoundException
	 * 		   if the file doesn't exist or can't be found
	 * @throws IOException
	 * @throws DataFormatException
	 * 		   if it does not have the expected tokens
	 */
	public Catalog loadCatalog(String filename)
    				throws FileNotFoundException, 
    				       IOException,
    				       DataFormatException {
		
		BufferedReader fileIn =
				new BufferedReader( new FileReader(filename) );
		
		Catalog catalog = new Catalog();
		
		String line = fileIn.readLine();
		
		while( line != null ) {
		
			tokenizer = new StringTokenizer(line, TOKENIZER);
			tokenizer.nextToken();
			
			if( line.startsWith(COFFEE_PREFIX) ) 
				catalog.addProduct( readCoffee(line) );
			else if( line.startsWith(BREWER_PREFIX))
					catalog.addProduct( readCoffeeBrewer(line) );
			else if( line.startsWith(PRODUCT_PREFIX))
					catalog.addProduct( readProduct(line) );
			else {
				
				throw new DataFormatException( line );
			}
			
			line = fileIn.readLine();
		}
		
		fileIn.close();
		
		return catalog;
	}
}