jsp+servlet实现商城购物车功能

加入购物车

商品详情页选中“加入购物车”后跳到AddCart

public class AddCart extends HttpServlet {
	
   
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String id=request.getParameter("id");
		ProductService ps=new ProductService();
		Book b=ps.findBookById(id);
		HttpSession session=request.getSession();
		//从session中获取购物车对象
		Map cart=(Map)session.getAttribute("cart");
		//如果购物车为空，说明没有商品存储在购物车中，创建除购物车
		if(cart==null) {
			cart=new HashMap() ;	
		}
		//向购物车添加商品数量信息
		Integer count=cart.put(b, 1);
		//如果商品数量不为空，则商品数量+1，否则添加新的商品信息
		if(count!=null) {
			cart.put(b, count+1);
		}  
		session.setAttribute("cart", cart);
		request.getRequestDispatcher("cart.jsp").forward(request, response);;
	
	}

	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		doGet(request, response);
	}

}

以map集合存储Book对象还有购买数量，并且新建购物车，存进session中

 

			

				
 序号
				
 商品名称
				
价格
				
 数量
				
库存
				
小计
				
取消
			
		
		
		  
		 
		 

		   

		       
${vs.count}
		       
${entry.key.name}
		       
${entry.key.price }
		       

		           
		           、               
		           
		           
		           
		                   
		       
		       
${entry.key.pnum}
		       
${entry.key.price*entry.value}
		       

		          
		          、            X
               
		    
		 
		 
		 
		 

		
		

		    

	            
合计：  ${total}元
	            
	        
		
		

		

		

		

           继续购物
           立即买单
           
	

public class ChangeNumServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String id = request.getParameter("id");
		int num = Integer.parseInt(request.getParameter("num"));
		
		HttpSession session = request.getSession();
		Map cart = (Map) session.getAttribute("cart");
		ProductService ps=new ProductService();
		Book b=ps.findBookById(id);
		//如果商品数据为0，就删除对象
		if(num==0) {
			cart.clear();
		}else {
			cart.clear();
			cart.put(b, num);
		}
       
		request.getRequestDispatcher("cart.jsp").forward(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

通过id找到对应的book对象后，从session中取出集合，要先清空集合再重新存键值（书和购买数量进去），不清空就会导致一会的cart页面出现多行从购物车里遍历取出来的数据