Html页面：
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>图书选择页面</title>
</head>
<body>
<form action="Experiment/Car" method="post">
<input type="checkbox" name="book" value="java"/>java<br>
<input type="checkbox" name="book" value="javaweb"/>javaWeb<br>
<input type="checkbox" name="book" value="python"/>python<br>
<input type="submit" name="登录"/>
</form>
</body>
</html> 
实现购物车的功能：
package Experiment;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;
public class Car extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
resp.setContentType("text/html,chardrt=UTF-8");
PrintWriter out = resp.getWriter();
HttpSession hs = req.getSession();
Map<String,Integer> car = (Map<String, Integer>)hs.getAttribute("shoppingCar");
//如果回话域没有shoppingcar,则实例化一个
if(car==null){
car = new HashMap<String, Integer>();
}
//获取用户的所选择的商品
String[] book = req.getParameterValues("book");
// if(book!=null&&book.length>0){
// for(int i=0;i<book.length;i++){
// out.println(book[i]);
// }
// }
if(book!=null&&book.length>0){
for(String bookname:book){
//判断该物品是否在购物车中
if(car.get(bookname)!=null){
int num = car.get(bookname);
car.put(bookname,num+1);
}else{
car.put(bookname,1);
}
}
}
hs.setAttribute("shoppingCar",car);
resp.sendRedirect("http://localhost:8080/javaWeb_war_exploded/Experiment/CarList");
}
}
从会话域中取出购物车，并对购物车进行遍历显示。
package Experiment;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;
public class CarList extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
resp.setContentType("text/html,charset=UTF-8");
PrintWriter out = resp.getWriter();
HttpSession session = req.getSession();
Map<String,Integer> car = (Map<String, Integer>)session.getAttribute("shoppingCar");
if(car!=null&&car.size()>0){
out.println("your car list:<br>");
//遍历显示购物车里面的商品
for (String bookname:car.keySet()){
out.println(bookname+","+car.get(bookname)+"<br>");
}
}else{
out.println("no goods+<br>");
}
out.println("<a href = 'http://localhost:8080/javaWeb_war_exploded/BookChoose.jsp'>keep going");
}
}
