Ajax 学习

//SERVLET类

package com.ajax.app.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.ajax.beans.ShoppingCart;
import com.fasterxml.jackson.databind.ObjectMapper;

@WebServlet("/addToCart")//这里这样写注解后就不用再web.xml中配置servlet了
public class AddToCartServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1.获取请求参数：id , price
        
        String bookName = request.getParameter("id");
        int price = Integer.parseInt(request.getParameter("price"));
        
        //2.获取购物车对象。
        HttpSession session = request.getSession();
        ShoppingCart sc = (ShoppingCart) session.getAttribute("sc");
        if(sc == null){
            sc = new ShoppingCart();
            session.setAttribute("sc", sc);
        }
        
        //3.把点击的选项加入到购物车中
        sc.addToCart(bookName, price);
        
        //4.准备响应的JSON对象:{"bookName":"","totalNumber":1，"totalMoney":1}
        //这里的\"相当于一个'  但是这里不能写'
    /*    StringBuilder result = new StringBuilder();
        result.append("{")
              .append("\"bookName\":\""+bookName+"\"")
              .append(",")
              .append("\"totalNumber\":"+sc.getTotalNumber())
              .append(",")
              .append("\"totalMoney\":"+sc.getTotalMoney())
              .append("}");
        
        response.setContentType("text/javascript");
        response.getWriter().print(result.toString());*/
        
        ObjectMapper mapper = new ObjectMapper();
        response.setContentType("text/javascript");
        System.out.println(mapper.writeValueAsString(sc));
        //响应ShoppingCart对象的JSON字符串
        response.getWriter().print(mapper.writeValueAsString(sc));
        
        
    }

}


//ShoppingCart类

package com.ajax.beans;

import java.util.HashMap;
import java.util.Map;

public class ShoppingCart {
    
    //存放shoppingcartItem 的键 书名：值
    private Map<String, ShoppingCartItem> items = new HashMap<>();
    
    private String bookName;
    
    
    public void addToCart(String bookName, int price){
        this.bookName = bookName;
        if(items.containsKey(bookName)){
            ShoppingCartItem item = items.get(bookName);
            item.setNumber(item.getNumber() + 1);
            item.setPrice(item.getPrice()+price);
        }else {
            ShoppingCartItem item = new ShoppingCartItem();
            item.setBookName(bookName);
            item.setPrice(price);
            item.setNumber(1);
            
            items.put(bookName, item);
        }
        
    }
    
    public int getTotalNumber(){
        int total = 0;
        for(ShoppingCartItem item: items.values()){
            total += item.getNumber();
        }
        return total;
    }
    
    
    public int getTotalMoney(){
        int money = 0;
        for(ShoppingCartItem item: items.values()){
            money +=  item.getPrice();
        }
        return money;
    }

    public String getBookName() {
        return bookName;
    }

}