HomeServlet：
@WebServlet({ “/HomeServlet”, “/home” })
public class HomeServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public HomeServlet() {
super ();
}
protected void doGet(HttpServlet request request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding(“utf-8”);
response.setContentType(“text/html;charset=utf-8”);
PrintWriter out = response.getWriter();
out.print(“<h2>书单</h2><hr/><br/>”);
out.print(“人类简史<a href='”+request.getContextPath()+”/addCartTip?id=1′>加入购物车</a><br/>”);
out.print(“未来简史<a href='”+request.getContextPath()+”/addCartTip?id=2′>加入购物车</a><br/>”);
out.print(“世界简史<a href='”+request.getContextPath()+”/addCartTip?id=3′>加入购物车</a><br/>”);
out.print(“时间简史<a href='”+request.getContextPath()+”/addCartTip?id=4′>加入购物车</a><br/>”);
out.print(“<a href='”+request.getContextPath()+”/show/cart’>查看购物车</a><br/>”);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
AddCartTipServlet：
@WebServlet({ “/AddCartTipsServlet”, “/addCartTip” })
public class AddCartTipsServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public AddCartTipsServlet() {
super ();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding(“utf-8”);
response.setContentType(“text/html;charset=utf-8”);
Http Session session = request.getSession();
List<String> list = (List<String>) session.getAttribute(“cart”);
if (list== null ){
list= new ArrayList<>();
}
String id = request.getParameter(“id”);
list.add(id);
session.setAttribute(“cart”, list);
System.out.println(list.toString());
response.getWriter().println(“已加入购物车<br/>”
+ “<a href='”+request.getContextPath()+”/home’>继续购物</a><br/>”
+ “<a href='”+request.getContextPath()+”/show/cart’>查看购物车</a><br/>”);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
ShowCartSevlet：
@WebServlet({ “/ShowCartServlet”, “/show/cart” })
public class ShowCartServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public ShowCartServlet() {
super ();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding(“utf-8”);
response.setContentType(“text/html;charset=utf-8”);
PrintWriter out = response.getWriter();
List<String> list = (List<String>)request.getSession().getAttribute(“cart”);
if (list!= null ){
out.print(“你的购物清单：<br/>”);
for (String string : list) {
out.println(DBUtils.findById(string)+”<br/>”);
}
out.println(“<br/><a href='”+request.getContextPath()+”/home’>继续购物</a><br/>”);
} else {
out.println(“你还没有将商品添加到购物车<br/>”
+ “<a href='”+request.getContextPath()+”/home’>返回商品列表</a><br/>”);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
DBUtils：存储着商品信息
public class DBUtils {
private static Map<String,String> map = new HashMap<>();
static {
map.put(“1”, “人类简史”);
map.put(“2”, “未来简史”);
map.put(“3”, “世界简史”);
map.put(“4”, “时间简史”);
}
public static String findById(String id){
return map.get(id);
}
}
