如何让asp.net的页面（类）定时运行

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我们有时候写的程序没有前台的页面，只是一个对数据库操作的过程，因为它的操作可能会大量使用数据库。因为它占用的资源比较大，我们一般都会让他在半夜的时候显示。这时候我们可以采用数据库的作业功能。可是有一个问题是，如果我们的这个操作还要从别的网站页面中取得相应的信息后，再进行处理。这怎么办呢。下面就是我采用的方法。

我要完成的功能是这样的，根据我数据库中的IP，到www.ip138.com上取得相应的地址，然后存入数据库中。

下面是我的代码(我建立的是一个类)
这个类是我要运行的代码，你要在Global.asax中运行它

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Text;
using System.Net;
using System.Threading;
using System.Data;
using System.Data.SqlClient;
using System.Collections;

namespace getPageValue
{
public class TimeRun
{

#region 数据库操作
public string dbType = "0";

public SqlConnection conn = new SqlConnection("server=.;uid=sa;pwd=123;database=DBCT_Dev");
//public SqlConnection conn = new SqlConnection("server=221.208.196.14;uid=hesdb;pwd=hes@2007;database=NEW_HEasySchoolDB");

public SqlCommand cmd;

public SqlDataAdapter da;

//关闭所有资源
public void Reset()
{
cmd.Dispose();
da.Dispose();
conn.Dispose();
conn.Close();
}

/// <summary>
/// 根据传入的语句，得到DataSet
/// </summary>
/// <param name="strsql"></param>
/// <returns></returns>
public DataSet GetDataSet(string strsql)
{
//this.Reset();

cmd = new SqlCommand("", conn);
cmd.CommandText = strsql;
DataSet ds = new DataSet();
da = new SqlDataAdapter();
da.SelectCommand = cmd;
da.Fill(ds);
return ds;
}

/// <summary>
/// 根据传入的语句，得到DataTable
/// </summary>
/// <param name="strsql"></param>
/// <returns></returns>
public DataTable GetDataTable(string strsql)
{
DataSet ds = GetDataSet(strsql);
return ds.Tables[0];
}

/// <summary>
/// 语句执行删除，插入，修改操作.
/// </summary>
/// <param name="strsql"></param>
/// <returns></returns>
public bool ExecuteSql(string strsql)
{
//this.Reset();
conn.Close();
conn.Open();
cmd = new SqlCommand("", conn);
cmd.CommandText = strsql;

return cmd.ExecuteNonQuery() != 0;
}

/// <summary>
/// 根据传入语句，取得相应数量，一般传入值为select count(*) from table
/// </summary>
/// <param name="strsql"></param>
/// <returns></returns>
public int ExecuteScalarSql(string strsql)
{
conn.Open();
cmd = new SqlCommand("", conn);
cmd.CommandText = strsql;

return Convert.ToInt32(cmd.ExecuteScalar());
//conn.Close();
}

/// <summary>
/// 根据传进来的值，取相应的字段
/// </summary>
/// <param name="GetTable">所要查询的表</param>
/// <param name="GetValue">所要得到的字段值</param>
/// <param name="Wherestr">条件语句</param>
/// <returns></returns>
public string GetSingleValue(string GetTable, string GetValue, string Wherestr)
{
string strsql = "select " + GetValue + " from " + GetTable + " where " + Wherestr + "";
DataTable dt = this.GetDataTable(strsql);
if (dt.Rows.Count > 0)
return dt.Rows[0][0].ToString();
else
return "无信息";
}

#endregion
private static ManualResetEvent allDone = new ManualResetEvent(false);

public static string singleip;
private static readonly TimeRun _ScheduledTask = null;
private System.Threading.Timer UpdateTimer = null;
//间隔时间，这里设置为15分钟
private int Interval = 15 * 60000;
private int _IsRunning;
static TimeRun()
{
_ScheduledTask = new TimeRun();
}
public static TimeRun Instance()
{
return _ScheduledTask;
}
public void Start()
{
if(UpdateTimer == null)
{
UpdateTimer = new System.Threading.Timer(new System.Threading.TimerCallback(UpdateTimerCallback), null, Interval, Interval);
}
}
private void UpdateTimerCallback(object sender)
{
if(Interlocked.Exchange(ref _IsRunning, 1) == 0)
{
try
{
//此处写你自己想执行的任务

if (DateTime.Now.ToShortTimeString() == "10:51")
{
//将数据库中Code为空ip不为空的记录存入，放到一个DataTable中。
string strsql = "select top 30 * from UserCode where UserIP<>'' and (Code is null or code = '')";

DataTable dt = GetDataTable(strsql);

for (int i = 0; i < dt.Rows.Count; i++)
{
//调用转化方法
getPost(dt.Rows[i]["id"].ToString());

//每次调用间隔一秒，通过实验得到，如果你的数据量大，最好间隔5秒
Thread.Sleep(5000);
}

dt.Dispose();
}
}
catch(Exception ex)
{
}
finally
{
Interlocked.Exchange(ref _IsRunning, 0);
}
}
}
public void Stop()
{
if(UpdateTimer != null)
{
UpdateTimer.Dispose();
UpdateTimer = null;
}
}

public void getPost(string id)
{

//singleid 传入的用户信息ID
//singleip 根据用户信息ID，而取到的IP
//strAction post必传值之一
//strCode　传入用户信息表中的code值

string singleid = id;

//通过GetSingleValue方法，得到相应的值，这里GetSingleValue（表名，要得到的值，条件语句）
singleip = GetSingleValue("UserCode", "UserIP", "id=" + singleid).Trim();

//建立HttpWebRequest
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create("http://www2.ip138.com/ips8.asp");
myRequest.Method = "POST";
myRequest.ContentType = "application/x-www-form-urlencoded";

//开始调用异步操作
myRequest.BeginGetRequestStream(new AsyncCallback(ReadCallback), myRequest);

allDone.WaitOne();

//异步回调方法使用 EndGetResponse 方法返回实际的 WebResponse。
HttpWebResponse response = (HttpWebResponse)myRequest.GetResponse();
Stream streamResponse = response.GetResponseStream();
StreamReader streamRead = new StreamReader(streamResponse, Encoding.Default);
string content = streamRead.ReadToEnd();

streamResponse.Close();
streamRead.Close();

response.Close();

//判断是否是有省市的信息，如果信息中有省，市，则进行存入数据库。其它信息，则为0035进入其它
//string singleip = "";
string strCode = "";

if (singleip == "127.0.0.1")
{
strCode = "0008";
}
else
{
if (content.IndexOf("省") == -1 && content.IndexOf("市") == -1 && singleid != "127.0.0.1")
{
if (content.IndexOf("查询太频繁") != -1)
{
strCode = "查询太频繁";
}
else
{
strCode = "0035";
}
}
else
{
if (content.IndexOf("省") != -1)
{
string con = content.Substring(content.IndexOf("本站主数据") + 6, content.IndexOf("</li><li>参考数据一") - content.IndexOf("本站主数据") - 1);
string strpro = con.Substring(0, con.IndexOf("省") + 1);
strCode = GetSingleValue("S_Province", "ProvinceCode", "ProvinceName='" + strpro + "'").Trim();
//strCode = strpro;
}

if (content.IndexOf("市") != -1)
{
string con = content.Substring(content.IndexOf("本站主数据") + 6, content.IndexOf("</li><li>参考数据一") - content.IndexOf("本站主数据") - 1);
string strpro = con.Substring(con.IndexOf("省") + 1, con.IndexOf("市") - con.IndexOf("省"));
strCode += GetSingleValue("S_City", "ZipCode", "CityName='" + strpro + "'").Trim(); ;
}
}

}

if (strCode == "")
{
strCode = "0035";
}

//将信息存入hashtable

string strsql = "update UserCode set Code='" + strCode + "' where id=" + id + "";
try
{
ExecuteSql(strsql);
}
catch
{

}

}

private void ReadCallback(IAsyncResult asynchronousResult)
{
try
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;

Stream postStream = request.EndGetRequestStream(asynchronousResult);

ASCIIEncoding encoding = new ASCIIEncoding();
string postData = "ip=" + singleip;
postData += "&action=2";
byte[] data = encoding.GetBytes(postData);

postStream.Write(data, 0, postData.Length);
postStream.Close();

allDone.Set();
}
catch
{ return; }

}

}
}

Global.asax文件中的代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;
using System.Timers;

namespace getPageValue
{

public class Global : System.Web.HttpApplication
{

protected void Application_Start(object sender, EventArgs e)
{
TimeRun.Instance().Start();
}

private void mess(object sender, ElapsedEventArgs e)
{
TimeRun.Instance().Stop();
}

protected void Session_Start(object sender, EventArgs e)
{

}

protected void Application_BeginRequest(object sender, EventArgs e)
{

}

protected void Application_AuthenticateRequest(object sender, EventArgs e)
{

}

protected void Application_Error(object sender, EventArgs e)
{

}

protected void Session_End(object sender, EventArgs e)
{

}

protected void Application_End(object sender, EventArgs e)
{

}
}
}