使用ASP.NET Cache 的 CacheDependency 來偵測資料庫是否變更

2008-04-12

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ASP.NET

小弟前陣子在討論區看到此篇文章...經過測試後有小小心得..分享給大家呀...

首先準備下列檔案：

CacheDependencyDataAdd.aspx,CacheDependencyDataAdd.aspx.cs→做資料更新網頁

CacheDependencyDemo.aspx,CacheDependencyDemo.aspx.cs→做資料瀏覽網頁

CheckChange.txt→檢查資料是否有更改的文字檔(內容空的)

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CacheDependencyDemo.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="CacheDependencyDemo.aspx.cs" Inherits="CacheDependencyDemo" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>CacheDependencyDemo</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server">
        </asp:GridView>

    </div>
    </form>
</body>
</html>

CacheDependencyDemo.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.Web.Caching;

using System.Data.SqlClient;

public partial class CacheDependencyDemo : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

if (Cache["data"] == null)

{

DataTable dt = GetData();

//增加一個檢查資料是否有更改的文字檔

CacheDependency file = new CacheDependency(Server.MapPath("CheckChange.txt"));

Cache.Insert("data", dt, file, DateTime.MaxValue, TimeSpan.FromMinutes(10));

this.GridView1.DataSource = dt;

this.GridView1.DataBind();

Response.Write("no Cache");

}

else

{

DataTable dt = (DataTable)Cache["data"];

this.GridView1.DataSource = dt;

this.GridView1.DataBind();

Response.Write("use Cache");

}

//取得資料

protected DataTable GetData()

{

using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))

{

string queryString = "SELECT * FROM [user]";

SqlCommand cmd = new SqlCommand(queryString, conn);

SqlDataAdapter adapter = new SqlDataAdapter(cmd);

DataTable dt = new DataTable();

adapter.Fill(dt);

return dt;

}

CacheDependencyDataAdd.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="CacheDependencyDataAdd.aspx.cs" Inherits="CacheDependencyDataAdd" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>CacheDependencyDataAdd</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="id"
            DataSourceID="SqlDataSource1" OnRowUpdated="GridView1_RowUpdated">
            <Columns>
                <asp:CommandField ShowEditButton="True" />
                <asp:BoundField DataField="id" HeaderText="id" InsertVisible="False" ReadOnly="True"
                    SortExpression="id" />
                <asp:BoundField DataField="name" HeaderText="name" SortExpression="name" />
                <asp:BoundField DataField="tel" HeaderText="tel" SortExpression="tel" />
                <asp:BoundField DataField="gender" HeaderText="gender" SortExpression="gender" />
            </Columns>
        </asp:GridView>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
            SelectCommand="SELECT * FROM [user]" UpdateCommand="UPDATE [user] SET name = @name, tel = @tel, gender = @gender WHERE (id = @id)">
            <UpdateParameters>
                <asp:Parameter Name="name" />
                <asp:Parameter Name="tel" />
                <asp:Parameter Name="gender" />
            </UpdateParameters>
        </asp:SqlDataSource>

    </div>
    </form>
</body>
</html>

CacheDependencyDataAdd.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.IO;

public partial class CacheDependencyDataAdd : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void GridView1_RowUpdated(object sender, GridViewUpdatedEventArgs e)

{

//資料有更新時,將檢查資料是否有更改的文字檔,做更新動作,如果沒做此動作資料不會馬上更新

using (System.IO.StreamWriter StreamWriter1 = new StreamWriter(Server.MapPath("CheckChange.txt")))

{

//寫入一串文字,讓文字檔有異動過

StreamWriter1.WriteLine(DateTime.Now.ToString());

}

執行如果：

CacheDependencyDemo

CacheDependencyDataAdd

參考網址：

http://www.blueshop.com.tw/board/show.asp?subcde=BRD20080402082116KNJ&fumcde=FUM20041006161839LRJ

http://aspnet.4guysfromrolla.com/articles/121802-1.aspx

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