How to make a simple shopping cart with java and jsp

& lt%@? Peggy? language="java "？ content type = " text/html； ? charset=utf-8 "

page encoding = " utf-8 " % & gt；

& lt%@? taglib？ prefix="c "？ uri= "

& lt%@? taglib？ uri= "

& lt！ DOCTYPE？ html？ Public? “-//W3C//DTD？ XHTML？ 1.0? Transition //EN "? "

& lthtml？ xmlns= "

& lthead & gt

& ltmeta？ . kaka.web

Import? Java . io . io exception；

Import? Java . io . printwriter；

Import? Java . util . ArrayList；

Import? Java . util . list；

Import? javax . servlet . servlet exception；

Import? javax.servlet..Kaka . entity . items；

Import? Com.kaka.entity.product;

Import? com . Kaka . service . product service；

Import? com . Kaka . service . impl . productserviceimpl；

Public? Class? Family car? Extension? HttpServlet？ {

Private? Static electricity Final? Dragon? serialVersionUID？ =? 1L；

ProductService？ ps？ =? New? ProductServiceImpl()；

@ Overlay

Protected? Invalid? doPost(HttpServletRequest？ req？ HttpServletResponse？ resp)？ Throwing? ServletException，？ IOException？ {

//Get the id of the goods

String? proId？ =? req . getparameter(" proId ")；

resp . set content type(" text/html； charset = UTF-8 ")；

Printmaker? A writer? =? resp . get writer()；

if(null？ ! =? proId？ & amp& amp？ ! "".Equal to (proId)){

//Return that the shopping cart was added successfully.

//system . out . println(" = = = = = = = = = = = = = "？ +? proId)；

//Query goods according to their id.

Try it? {

Integer? pId？ =? integer . parse int(proId)；

Product? Product? =? PS . findproductbyid(pId)；

if(null？ ! =? Product) {

//After finding the goods, construct the relevant parameters of the goods into a shopping detail and put it in the shopping cart.

Articles? It? =? New? items()；

it . set proid(product . get proid())；

it . set proname(product . getproname())；

it . set proprice(product . get proprice())；

it . setproimg(product . getproimg())；

//First, judge whether there is a shopping cart within the conversation range.

List & ltItems & gt? Shops, cars? =? (list & ltItems & gt)req.getSession (). get attribute(" shopCar ")；

if(null？ ==? Shop car)

//Shopping cart

Shops, cars? =? New? ArrayList & ltItems & gt();

}

//Before adding the goods to the shopping cart, judge whether the shopping details have been included in the shopping cart. If yes, just modify the purchase quantity.

if(shopCar.contains(it)){

int？ Index =? shop car . index of(it)； //Find the location of the shopping details in the shopping cart.

Articles? Articles? =? shopcar . get(index)； //Get the shopping details in the shopping cart.

items . set pronum(items . getpronum()+ 1)；

}? Or what? {

shopcar . add(it)；

}

//Put the shopping cart into the session for access.

req.getSession()。 setAttribute("shopCar "，shop car)；

//Return

writer . print(true)；

}? Or what? {

writer . print(false)；

}

}? Catch? (exception? e)？ {

e . printstacktrace()；

writer . print(false)；

}

}? Or what? {

writer . print(false)；

}

writer . flush()；

writer . close()；

}

@ Overlay

Protected? Invalid? doGet(HttpServletRequest？ req？ HttpServletResponse？ resp)？ Throwing? ServletException，？ IOException？ {

DoPost (request, resp);

}

}

Background management servlet?

Parcel? com . Kaka . web；

Import? Java . io . io exception；

Import? Java . io . printwriter；

Import? Java . util . ArrayList；

Import? Java . util . list；

Import? javax . mail . fetch profile . item；

Import? javax . servlet . servlet exception；

Import? javax.servlet..Kaka . entity . items；

Import? Com.kaka.entity.product;

Import? com . Kaka . service . product service；

Import? com . Kaka . service . impl . productserviceimpl；

Public? Class? HomeCarManager？ Extension? HttpServlet？ {

Private? Static electricity Final? Dragon? serialVersionUID？ =? 1L；

ProductService？ ps？ =? New? ProductServiceImpl()；

@ Overlay

Protected? Invalid? doPost(HttpServletRequest？ req？ HttpServletResponse？ resp)？ Throwing? ServletException，？ IOException？ {

resp . set content type(" text/html； charset = UTF-8 ")；

Printmaker? A writer? =? resp . get writer()；

//Get parameters

String? proId？ =? req . getparameter(" proId ")；

String? num？ =? req . getparameter(" num ")；

if(null？ ! =? proId？ & amp& amp？ null？ ! =? figure

& amp& amp？ ! "".Is equal to (proId)? & amp& amp？ ! "".Equal to (number)) {

Try it? {

Integer? pId？ =? integer . parse int(proId)；

Floating? pNum？ =? float . parse float(num)；

//Obtain the corresponding detailed items according to the id of the goods.

//? First, judge whether there is a shopping cart within the conversation range.

List & ltItems & gt? Shop, car? =? (list & ltItems & gt)? req.getSession()。 get attribute(" shopCar ")；

For (items? It? :? Shop car)

if(it.getProId()==？ pId){

it . setpronum(pNum)；

}

}

writer . print(true)；

}? Catch? (exception? e)？ {

e . printstacktrace()；

}

}? Or what? {

//Delete operation

Try it? {

Integer? pId？ =? integer . parse int(proId)；

//Obtain the corresponding detailed items according to the id of the goods.

//? First, judge whether there is a shopping cart within the conversation range.

List & ltItems & gt? Shop, car? =? (list & ltItems & gt)? req.getSession()。 get attribute(" shopCar ")；

Articles? Articles? =? null

For (items? It? :? Shop car)

if(it.getProId()==？ pId){

Articles? =? It;

Break;

}

}

if(null？ ! =? Project) {

shopcar . remove(items)；

req.getSession()。 SetAttribute("shopCar ");

}

writer . print(true)；

}? Catch? (exception? e)？ {

e . printstacktrace()；

}

}

writer . flush()；

writer . close()；

}

@ Overlay

Protected? Invalid? doGet(HttpServletRequest？ req？ HttpServletResponse？ resp)？ Throwing? ServletException，？ IOException？ {

DoPost (request, resp);

}

}