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。