ASP.NET购物车实现过程详解

1、 将test数据库附加到数据库管理系统中；数据库中的book_info包含下列数据：

2、 新建一个网站，将images文件夹复制到网站中；
3、 在default.aspx中，通过datalist控件展示数据库中的所有数据，以行为主序，每行3列，单击购买按钮时，将商品的id和数量保存到hashtable中，并将hashtable放置到session中。

protected void datalist1_itemcommand(object source, datalistcommandeventargs e) 
  { 
    string id = e.commandargument.tostring(); 
    hashtable ht; 
    if (session["shopcar"] == null) 
    { 
      ht = new hashtable(); 
      ht.add(id, 1); 
      session["shopcar"] = ht; 
    } 
    else 
    { 
      ht = (hashtable)session["shopcar"]; 
      if (ht.contains(id)) 
      { 
        int count = int.parse(ht[id].tostring()); 
        ht[id] = count + 1; 
        session["shopcar"] = ht; 
        response.write(count + 1); 
      } 
      else 
      { 
        ht.add(id, 1); 
        session["shopcar"] = ht; 
      } 
    } 
  } 

4、 在default.aspx中添加一个超链接，链接到shopcart.aspx,在shopcart.aspx中显示用户购买的商品信息。
提示：

a、在shopcart中先定义下列变量：

hashtable ht;
  datatable dt;
  string connstring=@"datasource=.\sqlexpress;initial catalog=test;integrated security=true";
  sqlconnection conn;
  sqlcommand cmd;
 sqldatareader sdr;

b、页面中添加一个gridview。
c、在page_load中，将dt实例化，建立各列。

protected void page_load(object sender, eventargs e)
  {
    dt = new datatable();
    datacolumn col = new datacolumn();
    col.columnname= "id";
    col.datatype =system.type.gettype("system.string");
    dt.columns.add(col);
    col = new datacolumn();
    col.columnname= "name";
    col.datatype =system.type.gettype("system.string");
    dt.columns.add(col);
    col = new datacolumn();
    col.columnname= "num";
    col.datatype =system.type.gettype("system.int32");
    dt.columns.add(col);
    col = new datacolumn();
    col.columnname= "price";
    col.datatype =system.type.gettype("system.single");
    dt.columns.add(col);
    col = new datacolumn();
    col.columnname= "total";
    col.datatype =system.type.gettype("system.single");
    dt.columns.add(col);
    if (!ispostback)
    {
      bind();
    }
  }
 
 
  public void bind()
  {
    
 
    if (session["shopcar"] == null)
    {
      response.write("<script>if(confirm('你没有登录')window.location='default15.aspx';else window.close();</script>");
    }
    else
    {
      ht = (hashtable)session["shopcar"];
      foreach (object item in ht.keys)
      {
        string id = item.tostring();
        int num = int.parse(ht[item].tostring());
        string sql = "selectbook_name,price from book_info where book_id='" + id + "'";
        conn = new sqlconnection(connstring);
        cmd = new sqlcommand(sql, conn);
        conn.open();
        sdr =cmd.executereader();
        if (sdr.hasrows)
        {
          sdr.read();
          datarow row = dt.newrow();
          row["id"] = id;
          row["num"] = num;
          row["name"] = sdr.getstring(0);
          row["price"] =float.parse(sdr[1].tostring());
          row["total"] =num*(float.parse(sdr[1].tostring()));
          dt.rows.add(row);
        }
        sdr.close();
        conn.close();
               
      }
      gridview1.datasource = dt.defaultview;
      gridview1.databind();
    }
}

d、这时可以看到用户购买的商品，但不能修改数量，也不能删除。
e、添加修改数量，删除商品功能，在aspx页面中定义gridview中的各列：

 <asp:gridview id="gridview1" runat="server" autogeneratecolumns="false">
     <columns>
       <asp:boundfield datafield="id" headertext="id" />
       <asp:boundfield datafield="name" headertext="名称" />
       <asp:boundfield datafield="price" headertext="价格" />
       <asp:templatefield>      
        <itemtemplate>
         <asp:textbox runat="server" id="textbox1" text='<%# eval("num") %>'
            ontextchanged="textbox1_textchanged" autopostback="true" ></asp:textbox>
        </itemtemplate>      
       </asp:templatefield>
      <asp:boundfield datafield="total" headertext="总计" />
      <asp:templatefield>
       <itemtemplate>
        <asp:button runat="server" id="button1" commandargument='<%# eval("id") %>'
           text="删除" onclick="button1_click" />
       
       </itemtemplate>
      
      </asp:templatefield>
     </columns>     
    </asp:gridview>

f、为gridview中的文本框添加textchanged事件：

protected void textbox1_textchanged(object sender, eventargs e)
  {
    
    hashtable ht =(hashtable)session["shopcar"];
    if (ht == null) return;
    for (int i = 0; i < gridview1.rows.count;i++)
    {
      string id =gridview1.rows[i].cells[0].text.tostring();
      response.write(id);
      string num = ((textbox)gridview1.rows[i].findcontrol("textbox1")).text;
      response.write("  "+num+"<br />");
      ht[id] = num;
    }
    session["shopcar"] = ht;
    bind();
   
  }

g、为按钮添加单击事件：

protected void button1_click(object sender, eventargs e)
  {
    string id = ((button)sender).commandargument;
    hashtable ht = (hashtable)session["shopcar"];
    if (ht == null) return;
    ht.remove(id);
    bind();
}

购物车代码：showcart.aspx.cs

using system; 
using system.collections.generic; 
using system.linq; 
using system.web; 
using system.web.ui; 
using system.web.ui.webcontrols; 
using system.collections; 
using system.data; 
using system.data.sqlclient; 
 
public partial class shopcart : system.web.ui.page 
{ 
  hashtable ht; 
  datatable dt; 
  string connstr = "data source=.\\sqlexpress;attachdbfilename=f:

\\test.mdf;integrated security=true;connect timeout=30;user instance=true"; 
  sqlconnection conn; 
  sqlcommand cmd; 
  sqldatareader sdr; 
  protected void page_load(object sender, eventargs e) 
  { 
    dt = new datatable(); 
    datacolumn col = new datacolumn(); 
    col.columnname = "id"; 
    col.datatype = system.type.gettype("system.string"); 
    dt.columns.add(col); 
    col = new datacolumn(); 
    col.columnname = "name"; 
    col.datatype = system.type.gettype("system.string"); 
    dt.columns.add(col); 
    col = new datacolumn(); 
    col.columnname = "num"; 
    col.datatype = system.type.gettype("system.int32"); 
    dt.columns.add(col); 
    col = new datacolumn(); 
    col.columnname = "price"; 
    col.datatype = system.type.gettype("system.single"); 
    dt.columns.add(col); 
    col = new datacolumn(); 
    col.columnname = "total"; 
    col.datatype = system.type.gettype("system.single"); 
    dt.columns.add(col); 
 
    if (!ispostback) 
    { 
      bind(); 
    } 
 
  } 
 
  public void bind() 
  { 
    if (session["shopcar"] == null) 
    { 
      response.write("<script>if(confirm('你没有登录')window.location='default.aspx';else window.close();</script>"); 
    } 
    else 
    { 
      ht = (hashtable)session["shopcar"]; 
      foreach (object item in ht.keys) 
      { 
        string id = item.tostring(); 
 
        int num = int.parse((ht[item].tostring())); 
        string sql = "select book_name,price from book_info where book_id='" + id + "'"; 
        conn = new sqlconnection(connstr); 
 
        cmd = new sqlcommand(sql, conn); 
        conn.open(); 
 
        sdr = cmd.executereader(); 
        if (sdr.hasrows) 
        { 
          sdr.read(); 
          datarow row = dt.newrow(); 
          row["id"] = id; 
          row["num"] = num; 
          row["name"] = sdr.getstring(0); 
          row["price"] = float.parse(sdr[1].tostring()); 
          row["total"] = num * (float.parse(sdr[1].tostring())); 
          dt.rows.add(row); 
 
        } 
        sdr.close(); 
        conn.close(); 
      } 
    } 
    gridview1.datasource = dt.defaultview; 
    gridview1.databind(); 
 
  } 
  protected void textbox1_textchanged(object sender, eventargs e) 
  { 
    hashtable ht = (hashtable)session["shopcar"]; 
    if (ht == null) return; 
    for (int i = 0; i < gridview1.rows.count; i++) 
    { 
      string id = gridview1.rows[i].cells[0].text.tostring(); 
      response.write(id); 
      string num = ((textbox)gridview1.rows[i].findcontrol("textbox1")).text; 
      response.write("  " + num + "<br />"); 
      ht[id] = num; 
    } 
    session["shopcar"] = ht; 
    bind(); 
 
  } 
  protected void button1_click(object sender, eventargs e) 
  { 
    string id = ((button)sender).commandargument; 
    hashtable ht = (hashtable)session["shopcar"]; 
    if (ht == null) return; 
    ht.remove(id); 
    bind(); 
 
  } 
} 

制作一个简单的购物车就是这么简单，大家可以按照我的思路进行创作，在此基础上在添加一些功能。