一个简单的购物车供初学者学习

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections;
/// <summary>
/// Shopping 的摘要说明
/// </summary>
public class Shopping
{
    //购物车
    public Hashtable SelectedGoods = new Hashtable();
    public Shopping()
    {

    }
}

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page 
{
    private Shopping obj;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["goods"]==null)
        {
            obj = new Shopping();
            Session["goods"] = obj;
        }
        else
        {
            obj = Session["goods"] as Shopping;
        }
        if (!IsPostBack)
        {
            ShowSelectedGoods();//显示被选中的商品
        }
    }
    protected void btnShoppingGoods_Click(object sender, EventArgs e)
    {
        SaveSelectedGoods();//保存被选中的商品
        Response.Redirect("ShowGoods.aspx");

    }
    protected void btnNextBuyComputer_Click(object sender, EventArgs e)
    {
        SaveSelectedGoods();
        Response.Redirect("BuyComputer.aspx");
    }

    private void SaveSelectedGoods()
    {
        CheckBox chk;
        //循环检查位于窗体上的所有控件
        foreach (Control ctl in form1.Controls)
        {
            //如果控件类型名为“CheckBox”
            if (ctl.GetType().Name == "CheckBox")
            {
                chk = ctl as CheckBox;
                //检查一下购物车中是否已有此书了
                if (obj.SelectedGoods.ContainsKey("book:" + chk.ID))
                {
                    if (chk.Checked == false)
                        //从购物车中移除此书
                        obj.SelectedGoods.Remove("book:" + chk.ID);
                }
                else  //购物车中没有此书
                    if (chk.Checked)  //复选框选中
                        //向购物车中添加此书
                        obj.SelectedGoods.Add("book:" + chk.ID, chk.Text);
            }
        }
        //将购物车对象保存到session中
        Session["goods"] = obj;
    }

    private void ShowSelectedGoods()
    {
        foreach (Control ctl in form1.Controls)
            if (ctl.GetType().Name == "CheckBox")
                (ctl as CheckBox).Checked = false;


        foreach (Object key in obj.SelectedGoods.Keys)
        {
            if (key.ToString().IndexOf("book:") != -1)
            {
                string id = key.ToString().Substring(key.ToString().LastIndexOf(":") + 1);
                Control ctl = form1.FindControl(id);
                if (ctl != null)
                    (ctl as CheckBox).Checked = true;
            }
        }
    }
}

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class BuyComputer : System.Web.UI.Page
{
    private Shopping obj;
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["goods"] == null)
        {
            obj = new Shopping();
            Session["goods"] = obj;
        }
        else
        {
            obj = Session["goods"] as Shopping;
        }
        if (!IsPostBack)
        {
            ShowSelectedArticles();
        }
    }
    protected void btnBuyBook_Click(object sender, EventArgs e)
    {
        SaveSelectedArticles();
        Response.Redirect("BuyBook.aspx");
    }

    private void SaveSelectedArticles()
    {
        CheckBox chk;
        //循环检查位于窗体上的所有控件
        foreach (Control ctl in form1.Controls)
        {
            //如果控件类型名为“CheckBox”
            if (ctl.GetType().Name == "CheckBox")
            {
                chk = ctl as CheckBox;
                //检查一下购物车中是否已有此电脑商品了
                if (obj.SelectedGoods.ContainsKey("computer:" + chk.ID))
                {
                    if (chk.Checked == false)
                        //从购物车中移除此电脑商品
                        obj.SelectedGoods.Remove("computer:" + chk.ID);
                }
                else  //购物车中没有此电脑商品
                    if (chk.Checked)  //复选框选中
                        //向购物车中添加此电脑商品
                        obj.SelectedGoods.Add("computer:" + chk.ID, chk.Text);
            }
        }
        //将购物车对象保存到session中
        Session["articles"] = obj;
    }

    private void ShowSelectedArticles()
    {
        foreach (Control ctl in Controls)
            if (ctl.GetType().Name == "CheckBox")
                (ctl as CheckBox).Checked = false;


        foreach (Object key in obj.SelectedGoods.Keys)
        {
            if (key.ToString().IndexOf("computer:") != -1)
            {
                string id = key.ToString().Substring(key.ToString().LastIndexOf(":") + 1);
                Control ctl = form1.FindControl(id);
                if (ctl != null)
                    (ctl as CheckBox).Checked = true;
            }

        }
    }
    protected void btnShoppingGoods_Click(object sender, EventArgs e)
    {
        SaveSelectedArticles();
        Response.Redirect("ShowGoods.aspx");
    }
}

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class ShowGoods : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["goods"]==null)
        {
            Label lblinfo = new Label();
            lblinfo.Text = "无";
            PlaceHolder1.Controls.Add(lblinfo);
        }
        else
        {
            Shopping shop = Session["goods"] as Shopping;
            if (shop.SelectedGoods.Count==0)
            {
                Label lblinfo = new Label();
                lblinfo.Text = "无";
                PlaceHolder1.Controls.Add(lblinfo);
            }
            else
            {
                BulletedList list = new BulletedList();
                foreach (object key in shop.SelectedGoods.Keys)
                {
                    list.Items.Add(shop.SelectedGoods[key].ToString());
                }
                PlaceHolder1.Controls.Add(list);
            }
        }
    }
    protected void btnBuyBook_Click(object sender, EventArgs e)
    {
        Response.Redirect("BuyBook.aspx");
    }
    protected void btnBuyComputer_Click(object sender, EventArgs e)
    {
        Response.Redirect("BuyComputer.aspx");
    }
}