cookie来实现购物车功能

一、大概思路

　　1、从cookie中取商品列表

　　2、判断要添加的商品是否存在cookie中。

　　3、如果已添加过，则把对应的商品取出来，把要添加的商品的数量加上去。

　　4、如果没有添加过，则把改商品添加到商品列表中。

　　5、再把商品列表序列化，加入cookie中。

二、代码实现

　　1、定义一个购物车商品的pojo

public class cartitem {

    private long id;

    private string title;

    private long price;

    private integer num;

    private string image;

    public long getid() {
        return id;
    }

    public void setid(long id) {
        this.id = id;
    }

    public string gettitle() {
        return title;
    }

    public void settitle(string title) {
        this.title = title;
    }

    public long getprice() {
        return price;
    }

    public void setprice(long price) {
        this.price = price;
    }

    public integer getnum() {
        return num;
    }

    public void setnum(integer num) {
        this.num = num;
    }

    public string getimage() {
        return image;
    }

    public void setimage(string image) {
        this.image = image;
    }
}

　　2、定义一个购物车的接口和实现类

public interface cartservice {

    taotaoresult addcartservice(httpservletrequest request, httpservletresponse response, long itemid, integer num);
}

@service
public class cartserviceimpl implements cartservice {

    @autowired
    private itemservice itemservice;
    @value("${cookie_expire}")
    private integer cookie_expire;

    @override
    public taotaoresult addcartservice(httpservletrequest request, httpservletresponse response, long itemid, integer num) {
        // 1.从cookie中取商品列表
        list<cartitem> list = getcartfromcookie(request);
        // 2.判断是否已经添加过购物车
        boolean haveflag = false;
        for (cartitem c : list) {
            //3.如果添加过,把对应的商品取出来，数量加num
            if(c.getid().longvalue() == itemid) {
                c.setnum(c.getnum() + num);
                haveflag = true;
                break;
            }
        }
        // 4.如果没添加过,则把该商品添加进去。
        if (!haveflag) {
            tbitem item = itemservice.getitembyid(itemid);
            cartitem cartitem = new cartitem();
            cartitem.setnum(num);
            cartitem.setid(itemid);
            cartitem.setprice(item.getprice());
            cartitem.settitle(item.gettitle());
            if (item.getimage() != null) {
                string image = item.getimage();
                string[] strings = image.split(",");
                cartitem.setimage(strings[0]);
            }
            list.add(cartitem);
        }
        // 5.再把list返回到cookie中
        cookieutils.setcookie(request, response, "tt_cart", jsonutils.objecttojson(list), cookie_expire);
　　　　　　
        return taotaoresult.ok();
    }

    private list<cartitem> getcartfromcookie(httpservletrequest request) {
        try {
            string json = cookieutils.getcookievalue(request, "tt_token", true);
            list<cartitem> list = jsonutils.jsontolist(json, cartitem.class);
            if (list == null) {
                return new arraylist<>();
            }else {
                return list;
            }
        }catch (exception e) {
            return new arraylist<>();
        }
    }
}

 　　3、controller来接收前端的请求，并响应到cart-success.jsp页面。

@controller
public class cartcontroller {

    @autowired
    private cartservice cartservice;

    @requestmapping("/cart/add/{itemid}")
    public string addcart(@pathvariable long itemid, integer num, httpservletrequest request, httpservletresponse response) {
        taotaoresult result = cartservice.addcartservice(request, response, itemid, num);
        return "cart-success";
    }
}