使用JSP做购物车一（实现）

按照上篇文章的分析来具体实现：

定义所需包名来分工：

功能一：显示所有图书：

1、数据层：用双列集合来保存数据，用静态方法来添加数据里嵌套Book类（在实体类包domain里来创建，代码在下面）的构造方法，

public class DB {
	private static Map map=new LinkedHashMap();
	static
	{
		map.put("1", new Book("1","java","A",20));
		map.put("2", new Book("2","c++","B",21));
		map.put("3", new Book("3","PHP","C",22));
		map.put("4", new Book("4",".NET","D",23));
		map.put("4", new Book("5","Python","E",23));
		map.put("6", new Book("6","C#","F",23));
	}

          /*按照实施过程来创建查找方法，通过类名来调用该静态方法。返回map对象。即上篇文章的

             实施过程，可返回参考*/

         //注意map的key和value对应
	public static Map findAllBook()
	{
		
		return map;
		
	}
	public static Book findBookById(String id)
	{
		return DB.findBookById(id);
		
	}
}

2、实体层

public class Book {
	private String id;
	private String name;
	private String author;
	private double price;
	private int num=1;
	public Book() {
	}

            //即对应DB类里的new Book("1","java","A",20)
	public Book(String id, String name, String author, int price) {
		super();
		this.id = id;
		this.name = name;
		this.author = author;
		this.price = price;
	}

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getAuthor() {
		return author;
	}

	public void setAuthor(String author) {
		this.author = author;
	}

	public double getPrice() {
		return price;
	}

	public void setPrice(int price) {
		this.price = price;
	}

}

3、访问层

//访问层/持久层
public class BookDao {
	//查询所有的图书
	private DB db=new DB();
	public Map findAllBook()
	{
		return DB.findAllBook();
		
	}
	public static Book findBookById(String id){
		return DB.findBookById(id);
	}

}

4、业务层

public class BookService {

	private BookDao bookDao = new BookDao();
	// 查询所有图书
	public Map findAllBook() {
		return bookDao.findAllBook();
	}
	// 购买图书
	public void buyBook(String id, Car car) {
		// 取得图书列表
		Map map = car.getMap();
		// 根据id获得图书
		Item item = map.get(id);
		if (item == null) {
			Book book = bookDao.findBookById(id);
			// 加入购物车
			item = new Item();
			// Book book =new Book();

			item.setBook(book);
			item.setNum(1);
			map.put(id, item);

		} else {
			item.setNum(item.getNum() + 1);
		}
	}

	public void deleteBook(String id, Car car) {
		Map map = car.getMap();
		map.remove(id);
	}

	public void clearCar(Car car) {
		Map map = car.getMap();
		map.clear();
	}

	public void updateBook(String id, int num, Car car) {
		Map map = car.getMap();
		Item item = map.get(id);
		item.setNum(num);
	}

}

5、控制层

public class ListBookServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		BookService bookservice=new BookService();
		Map map=bookservice.findAllBook();
		request.setAttribute("map", map);
		//请求转发：
		request.getRequestDispatcher("/view/listAllBook.jsp").forward(request, response);
	}
}

6、显示层

listAllBook.jsp

	
			

		
图书列表
		

			
编号
			
书名
			
作者
			
单价
		
		

				
${entry.value.id}
				
${entry.value.name}
				
${entry.value.auther}
				
${entry.value.price}
				
购买