c#利用Session对象实现购物车的方法示例

//shopcart.aspx.cs

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;
using system.data.sqlclient;
using system.text.regularexpressions; 

public partial class shopcart : system.web.ui.page
{
  commonclass ccobj = new commonclass();
  dbclass dbobj = new dbclass();
  string strsql;
  datatable dttable;
  hashtable hashcar;
  protected void page_load(object sender, eventargs e)
  {
    if (!ispostback)
    {
      if (session["shopcart"] == null)
      {
        //如果没有购物，则给出相应信息，并隐藏按钮
        this.labmessage.text = "您还没有购物！";
        this.labmessage.visible = true;    //显示提示信息
        this.lnkbtncheck.visible = false;   //隐藏“前往服务台”按钮
        this.lnkbtnclear.visible = false;   //隐藏“清空购物车”按钮
        this.lnkbtncontinue.visible = false;  //隐藏“继续购物”按钮

      }
      else
      {
        hashcar = (hashtable)session["shopcart"]; //获取其购物车
        if (hashcar.count == 0)
        {
          //如果没有购物，则给出相应信息，并隐藏按钮
          this.labmessage.text = "您购物车中没有商品！";
          this.labmessage.visible = true;    //显示提示信息
          this.lnkbtncheck.visible = false;   //隐藏“前往服务台”按钮
          this.lnkbtnclear.visible = false;   //隐藏“清空购物车”按钮
          this.lnkbtncontinue.visible = false;  //隐藏“继续购物”按钮

        }
        else
        {
          //设置购物车内容的数据源
          dttable = new datatable();
          datacolumn column1 = new datacolumn("no");    //序号列
          datacolumn column2 = new datacolumn("bookid");  //书籍id代号
          datacolumn column3 = new datacolumn("bookname"); //书籍名称
          datacolumn column4 = new datacolumn("num");    //数量
          datacolumn column5 = new datacolumn("price");   //单价
          datacolumn column6 = new datacolumn("totalprice");//总价
          dttable.columns.add(column1); //添加新列      
          dttable.columns.add(column2);
          dttable.columns.add(column3);
          dttable.columns.add(column4);
          dttable.columns.add(column5);
          dttable.columns.add(column6);
          datarow row;
          //对数据表中每一行进行遍历，给每一行的新列赋值
          //foreach (object key in hashcar.keys)
          //{
          //  row = dttable.newrow();
          //  row["bookid"] = key.tostring();
          //  row["num"] = hashcar[key].tostring();
          //  dttable.rows.add(row);
          //}
          foreach (dictionaryentry hash in hashcar)
          {
            row = dttable.newrow();
            row["bookid"] = hash.key.tostring();
            row["num"] = hash.value.tostring();
            dttable.rows.add(row);
          }
          //计算价格
          datatable dstable;
          int i = 1;
          float price;//商品单价
          int count; //商品数量
          float totalprice = 0; //商品总价格
          foreach (datarow drrow in dttable.rows)
          {
            strsql = "select bookname,hotprice from tb_bookinfo where bookid=" + convert.toint32(drrow["bookid"].tostring());
            dstable = dbobj.getdatasetstr(strsql, "tbgi");
            drrow["no"] = i;//序号
            drrow["bookname"] = dstable.rows[0][0].tostring();//书籍名称
            drrow["price"] = (dstable.rows[0][1].tostring());//单价
            price = float.parse(dstable.rows[0][1].tostring());//单价
            count = int32.parse(drrow["num"].tostring());
            drrow["totalprice"] = price * count; //总价
            totalprice += price * count; //计算合价
            i++;
          }
          this.labtotalprice.text = "总价：" + totalprice.tostring(); //显示所有商品的价格
          this.gvshopcart.datasource = dttable.defaultview;  //绑定gridview控件
          this.gvshopcart.datakeynames = new string[] { "bookid" };
          this.gvshopcart.databind();
        }
      }
    
    }
    
  }
  public void bind()
  {
    if (session["shopcart"] == null)
    {
      //如果没有购物，则给出相应信息，并隐藏按钮
      this.labmessage.text = "您还没有购物！";
      this.labmessage.visible = true;    //显示提示信息
      this.lnkbtncheck.visible = false;   //隐藏“前往服务台”按钮
      this.lnkbtnclear.visible = false;   //隐藏“清空购物车”按钮
      this.lnkbtncontinue.visible = false;  //隐藏“继续购物”按钮
      
    }
    else
    {
      hashcar = (hashtable)session["shopcart"]; //获取其购物车
      if (hashcar.count == 0)
      {
        //如果没有购物，则给出相应信息，并隐藏按钮
        this.labmessage.text = "您购物车中没有商品！";
        this.labmessage.visible = true;    //显示提示信息
        this.lnkbtncheck.visible = false;   //隐藏“前往服务台”按钮
        this.lnkbtnclear.visible = false;   //隐藏“清空购物车”按钮
        this.lnkbtncontinue.visible = false;  //隐藏“继续购物”按钮
        
      }
      else
      {
        //设置购物车内容的数据源
        dttable = new datatable();
        datacolumn column1 = new datacolumn("no");    //序号列
        datacolumn column2 = new datacolumn("bookid");  //书籍id代号
        datacolumn column3 = new datacolumn("bookname"); //书籍名称
        datacolumn column4 = new datacolumn("num");    //数量
        datacolumn column5 = new datacolumn("price");   //单价
        datacolumn column6 = new datacolumn("totalprice");//总价
        dttable.columns.add(column1); //添加新列      
        dttable.columns.add(column2);
        dttable.columns.add(column3);
        dttable.columns.add(column4);
        dttable.columns.add(column5);
        dttable.columns.add(column6);
        datarow row;
        //对数据表中每一行进行遍历，给每一行的新列赋值
        foreach (object key in hashcar.keys)
        {
          row = dttable.newrow();
          row["bookid"] = key.tostring();
          row["num"] = hashcar[key].tostring();
          dttable.rows.add(row);
        }
        //计算价格
        datatable dstable;
        int i = 1;
        float price;//商品单价
        int count; //商品数量
        float totalprice = 0; //商品总价格
        foreach (datarow drrow in dttable.rows)
        {
          strsql = "select bookname,hotprice from tb_bookinfo where bookid=" + convert.toint32(drrow["bookid"].tostring());
          dstable = dbobj.getdatasetstr(strsql, "tbgi");
          drrow["no"] = i;//序号
          drrow["bookname"] = dstable.rows[0][0].tostring();//书籍名称
          drrow["price"] = (dstable.rows[0][1].tostring());//单价
          price = float.parse(dstable.rows[0][1].tostring());//单价
          count = int32.parse(drrow["num"].tostring());
          drrow["totalprice"] = price * count; //总价
          totalprice += price * count; //计算合价
          i++;
        }
        this.labtotalprice.text = "总价：" + totalprice.tostring(); //显示所有商品的价格
        this.gvshopcart.datasource = dttable.defaultview;  //绑定gridview控件
        this.gvshopcart.datakeynames=new string[] {"bookid"};
        this.gvshopcart.databind();
      }
    }
      
  
  
  }
  protected void lnkbtnupdate_click(object sender, eventargs e)
  {
    hashcar = (hashtable)session["shopcart"]; //获取其购物车
    //使用foreach语句，遍历更新购物车中的商品数量
    foreach (gridviewrow gvr in this.gvshopcart.rows)
    {
      textbox otb = (textbox)gvr.findcontrol("txtnum"); //找到用来输入数量的textbox控件 
      int count = int32.parse(otb.text);//获得用户输入的数量值
      string bookid = gvr.cells[1].text;//得到该商品的id代
      hashcar[bookid] = count;//更新hashtable表
    }
    session["shopcart"] = hashcar;//更新购物车
    response.redirect("shopcart.aspx");
  }
  protected void lnkbtndelete_command(object sender, commandeventargs e)
  {
    hashcar = (hashtable)session["shopcart"];//获取其购物车
    //从hashtable表中，将指定的商品从购物车中移除，其中，删除按钮(lnkbtndelete)的commandargument参数值为商品id代号
    hashcar.remove(e.commandargument);
    session["shopcart"] = hashcar; //更新购物车
    response.redirect("shopcart.aspx");
  }
  protected void lnkbtnclear_click(object sender, eventargs e)
  {
    session["shopcart"] =null;
    response.redirect("shopcart.aspx");
  }
  protected void lnkbtncontinue_click(object sender, eventargs e)
  {
    response.redirect("default.aspx");
  }
  protected void lnkbtncheck_click(object sender, eventargs e)
  {
    response.redirect("checkout.aspx");
  }
  protected void gvshopcart_pageindexchanging(object sender, gridviewpageeventargs e)
  {
    gvshopcart.pageindex = e.newpageindex;
    bind();

  }
  protected void txtnum_textchanged(object sender, eventargs e)
  {
    hashcar = (hashtable)session["shopcart"]; //获取其购物车
    foreach (gridviewrow gvr in this.gvshopcart.rows)
    {

      textbox otb = (textbox)gvr.findcontrol("txtnum"); //找到用来输入数量的textbox控件 
      int count = int32.parse(otb.text);//获得用户输入的数量值
      string bookid = gvr.cells[1].text;//得到该商品的id代
      hashcar[bookid] = count;//更新hashtable表

    }
    session["shopcart"] = hashcar;//更新购物车
    bind();

  }

//shopcart.aspx

            <table cellspacing="0" cellpadding="0" width="95%" align="center" border="0" style="font-size: 9pt">
               <tr>
               <td align="center">
                <asp:label id="labmessage" runat="server" visible="false"></asp:label></td>
              </tr>
              <tr>
               <td align="left" height =30px>
                <asp:label id="labtotalprice" runat="server" text="0.00 " ></asp:label>￥</td>
              </tr>
              <tr style =" font :9pt; font-family :宋体;" valign =top >
              <td align="left" style="height: 135px">
              
               <asp:gridview id="gvshopcart" datakeynames ="bookid"  runat="server" autogeneratecolumns="false" allowpaging="true" onpageindexchanging="gvshopcart_pageindexchanging" >
                 <columns>
                   <asp:boundfield datafield="no" headertext="序号" readonly="true">
                     <itemstyle horizontalalign="center" />
                     <headerstyle horizontalalign="center" />
                   </asp:boundfield> 
                   <asp:boundfield datafield="bookid" headertext="书籍id" readonly="true">
                     <itemstyle horizontalalign="center" />
                     <headerstyle horizontalalign="center" />
                   </asp:boundfield>                  
                   <asp:boundfield datafield="bookname" headertext="书籍名称" readonly="true">
                   <itemstyle horizontalalign="center" />
                   <headerstyle horizontalalign="center" />
                   </asp:boundfield> 
                   <asp:templatefield headertext="数量">
                  <itemtemplate >
                    <asp:textbox id="txtnum" runat="server" text =<%#eval("num") %> width =60px ontextchanged="txtnum_textchanged"></asp:textbox>
                    <asp:regularexpressionvalidator
                id="regularexpressionvalidator1" runat="server" controltovalidate="txtnum"
                errormessage="×" validationexpression="^\+?[1-9][0-9]*$"></asp:regularexpressionvalidator>
                </itemtemplate>
                </asp:templatefield>
                  
                   <asp:templatefield headertext =单价>
                     <headerstyle horizontalalign=center />
                     <itemstyle horizontalalign =center />
                     <itemtemplate >
                      <%#eval("price")%>￥
                     </itemtemplate>  
                   </asp:templatefield>
                  <asp:templatefield headertext =总价>
                     <headerstyle horizontalalign=center />
                     <itemstyle horizontalalign =center />
                     <itemtemplate >
                      <%#eval("totalprice")%>￥
                     </itemtemplate>  
                   </asp:templatefield>
                   <asp:templatefield>
                     <headerstyle horizontalalign=center />
                     <itemstyle horizontalalign =center />
                     <itemtemplate >
                       <asp:linkbutton id="lnkbtndelete" runat="server" commandargument ='<%#eval("bookid") %>' oncommand ="lnkbtndelete_command">删除</asp:linkbutton>
                     </itemtemplate>  
                   </asp:templatefield>
                   
                 </columns>
                </asp:gridview>
              </td>
              </tr>
              <tr align =left valign =top >
                <td align="center" >
                  <asp:linkbutton id="lnkbtnupdate" runat="server" onclick="lnkbtnupdate_click">更新购物车</asp:linkbutton>
                   <asp:linkbutton id="lnkbtnclear" runat="server" onclick="lnkbtnclear_click" >清空购物车</asp:linkbutton>
                  <asp:linkbutton id="lnkbtncontinue" runat="server" onclick="lnkbtncontinue_click" >继续购物</asp:linkbutton> 
                  <asp:linkbutton id="lnkbtncheck" runat="server" onclick="lnkbtncheck_click" >前往服务台</asp:linkbutton>
                  </td>
              </tr>
              <tr>
              <td align="left" >
                <br />
                 <li>如果要修改商品数量，请单击“更新购物车”按钮    </li> <li>如果要取消某个商品，请单击“删除”
              <br />
              </li>
              </td>
              </tr>
            </table>

default.aspx.cs //添加物品到购物车代码

  protected void dldiscount_itemcommand(object source, datalistcommandeventargs e)
  {
    if (e.commandname == "detailsee")
    {
      addressback(e);
    }
    else if (e.commandname == "buy")
    {
      addshopcart(e);
    } 

 

  }
  protected void dlhot_itemcommand(object source, datalistcommandeventargs e)
  {
    if (e.commandname == "detailsee")
    {
      addressback(e);
    }
    else if (e.commandname == "buy")
    {
      addshopcart(e);
    }

  }
  /// <summary>
  /// 向购物车中添加新商品
  /// </summary>
  /// <param name="e">
  /// 获取或设置可选参数，
  /// 该参数与关联的 commandname 
  /// 一起被传递到 command 事件。
  /// </param> 
  public void addshopcart(datalistcommandeventargs e)
  {
    hashtable hashcar;
    if (session["shopcart"] == null)
    {
      //如果用户没有分配购物车
      hashcar = new hashtable();     //新生成一个
      hashcar.add(e.commandargument, 1); //添加一个商品
      session["shopcart"] = hashcar;   //分配给用户
    }
    else
    {
      //用户已经有购物车
      hashcar = (hashtable)session["shopcart"];//得到购物车的hash表
      if (hashcar.contains(e.commandargument))//购物车中已有此商品，商品数量加1
      {
        int count = convert.toint32(hashcar[e.commandargument].tostring());//得到该商品的数量
        hashcar[e.commandargument] = (count + 1);//商品数量加1
      }
      else
        hashcar.add(e.commandargument, 1);//如果没有此商品，则新添加一个项
    }

  }


this.clientscript.registerstartupscript(this.gettype(),"",<script>alert("商品添加成功!")</script>);

private void datagrid1_itemcommand(object source, system.web.ui.webcontrols.datagridcommandeventargs e)//假设前面购买命令是一个命令名为buy的linkbutton
{//关键，建立和加如购物车
string pid=this.datagrid1.datakeys[e.item.itemindex].tostring();//取出编号
if(e.commandname=="buy")//如果命令名是 buy，说明是购买
{
if(session["bus"]==null)//先就得检查购物车是否存在,如果不存在,就建立 
{
system.collections.hashtable ht=new hashtable();//先建立一个哈希表
ht.add(pid,1);//哈希表中的两个列，一个key，一个value ，key放编号，value放购买数量好了，预设置为１
session["bus"]=ht;//将哈希表赋值给session对象
}
else//如果存在的话
{
hashtable ht=(hashtable)session["bus"];//使用强制类型转换，再将session["bus"]赋值给哈希表对象 ht
if(ht[pid]==null)//如果哈希表中对应的ｉｄ没有，
{
ht[pid]=1;//那就直接给他设为　１
}
else//如果已经有对应的ｉｄ
{
ht[pid]=(int)ht[pid]+1;//那么就把原来的取出来再加上　１
}
session["bus"]=ht;//最后再更新session 对象
}
}
 } 

this.datalist1.datasource=(hashtable)session["bus"];
this.datalist1.databind();
1private void linkbutton1_click(object sender, system.eventargs e)
{
 foreach(datalistitem dl in this.datalist1.items)//遍历集合
{
textbox tb=(textbox)dl.findcontrol("textbox1");//找到文本框
int newpid=convert.toint32(tb.text.tostring());//查出文本框里面的值
 label label1=(label)dl.findcontrol("key");//找到装载哈希表key字段的那个控件
string pid=label1.text.tostring();//把他的值拿出来
 hashtable ht=(hashtable)session["bus"];//把session["bus"]对象赋值给哈希表 ht
int oldpid=(int)ht[pid];//求得原来的数量
 if(newpid!=oldpid)//如果文本框里的值不等于原来的数量，就用新的更换到哈希表中的值
{
ht[pid]=newpid;
}
session["bus"]=ht;//最后再更新session 对象
}
}