Servlet/Jsp implement shopping cart and servletjsp shopping cart

Servlet/Jsp implement shopping cart and servletjsp shopping cart

(1) Use servlet to implement a simple Shopping Cart system. The Project structure is as follows: (to create a web Project, you only need to add three files: AddItemServlet, ListItemServlet, and exam403.jsp. Do not worry about other files)

(2) The exam403.jsp code is as follows:

<% @ Page contentType = "text/html; charset = gb2312" language = "java" import = "java. SQL. *" errorPage = "" %> <! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 

(3) The AddItemServlet code is as follows:


Package com. lc. shoppingCar; import javax. servlet. *; import javax. servlet. http. *; import java. io. *; import java. util. *; public class AddItemServlet extends HttpServlet {protected void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, java. io. IOException {ServletContext application = getServletContext (); ServletConfig config = getServletConfig (); response. setContentTyp E ("text/html; charset = gb2312"); PrintWriter out = response. getWriter (); HttpSession session = request. getSession (); request. setCharacterEncoding ("gb2312"); // read the product ID and quantity passed in the form. String id = request. getParameter ("itemID"); String num = request. getParameter ("quantity"); if (id! = Null & num. length ()! = 0) {// read the shopping cart HashMap shoppingCar = (HashMap) session from Sessionn. getAttribute ("shoppingCar"); if (shoppingCar = null) shoppingCar = new HashMap (); // Add the item to the cart String onum = (String) shoppingCar. get (id); if (onum = null) shoppingCar. put (id, num); else {int n1 = Integer. parseInt (num); int n2 = Integer. parseInt (onum); String result = String. valueOf (n1 + n2); shoppingCar. put (id, result);} // write the shopping cart back to the session to save the session. setAttr Ibute ("shoppingCar", shoppingCar);} else // If the input item ID number is blank or the number is blank, the System is displayed. out. print ("the ID of a product is blank, or the number is blank! "); // Return to the product list page response. sendRedirect ("/servletProject/exam403.jsp");} protected void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, java. io. IOException {doGet (request, response );}}

(4) The ListItemServlet code is as follows:


Package com. lc. shoppingCar; import javax. servlet. *; import javax. servlet. http. *; import java. io. *; import java. util. *; public class ListItemServlet extends HttpServlet {protected void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, java. io. IOException {ServletContext application = getServletContext (); ServletConfig config = getServletConfig (); response. setContentTy Pe ("text/html; charset = gb2312"); PrintWriter out = response. getWriter (); HttpSession session = request. getSession (); request. setCharacterEncoding ("gb2312"); // obtain the cart HashMap shoppingCar = (HashMap) session from the session. getAttribute ("shoppingCar"); // if (shoppingCar! = Null) {Set show = shoppingCar. entrySet (); Iterator it = show. iterator (); while (it. hasNext () {out. print (it. next () + "<br>") ;}} else out. print ("the shopping cart is empty! ");} Protected void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, java. io. IOException {doGet (request, response );}}

(5) The implementation effect is as follows:

Visit: http: // localhost: 8080/servletProject/exam403.jsp to learn how to submit the product


Click to view the shopping cart:


OK! This is the end of a simple shopping cart!

JSP interacts with Javascript Servlet to add a shopping cart.
Use form requests or xmlhttprequest.

Question about jsp shopping cart implementation
Your problem is a bit too long. You mean that the session has been saved, and your page jumps.
The page can be implemented using ajax without navigation. We recommend that you do not place the page in the session, because the online shopping mall system will see the items in the shopping cart during your next login, which are all stored in the database.
Session itself is a hash of key and value.