asp.net网站实现类似timer的定时任务

using System;using System.Data;using System.Data.SqlClient;using System.Security.Principal;using System.Threading;using System.Net;using System.Diagnostics;using System.Collections;using System.ComponentModel;using System.Web;using System.Web.Mail;using System.Web.Caching;using System.Web.SessionState;using System.IO;using System.Messaging;namespace TestCacheTimeout {/// <summary>/// Summary description for Global./// </summary>public class Global : System.Web.HttpApplication{private const string DummyPageUrl = "http://localhost/TestCacheTimeout/WebForm1.aspx";private const string CONNECTION_STRING = "Data Source=(local);Initial Catalog=tempdb;Integrated Security=SSPI;";private const string LOG_FILE = @"c:\temp\Cachecallback.txt";private const string MSMQ_NAME = ".\\private$\\ASPNETService";private const string DummyCacheItemKey = "GagaGuguGigi";public static ArrayList _JobQueue = new ArrayList();/// <summary>/// Required designer variable./// </summary>private System.ComponentModel.IContainer components = null;public Global(){InitializeComponent();}protected void Application_Start(Object sender, EventArgs e){RegisterCacheEntry();}/// <summary>/// Register a cache entry which expires in 1 minute and gives us a callback./// </summary>/// <returns></returns>private void RegisterCacheEntry(){// Prevent duplicate key additionif( null != HttpContext.Current.Cache[ DummyCacheItemKey ] ) return;HttpContext.Current.Cache.Add( DummyCacheItemKey, "Test", null, DateTime.MaxValue,TimeSpan.FromMinutes(1), CacheItemPriority.NotRemovable,new CacheItemRemovedCallback( CacheItemRemovedCallback ) );}/// <summary>/// Callback method which gets invoked whenever the cache entry expires./// We can do our "service" works here./// </summary>/// <param name="key"></param>/// <param name="value"></param>/// <param name="reason"></param>public void CacheItemRemovedCallback(string key,object value,CacheItemRemovedReason reason){Debug.WriteLine("Cache item callback: " DateTime.Now.ToString() );// Do the service worksDoWork();// We need to register another cache item which will expire again in one// minute. However, as this callback occurs without any HttpContext, we do not// have access to HttpContext and thus cannot access the Cache object. The// only way we can access HttpContext is when a request is being processed which// means a webpage is hit. So, we need to simulate a web page hit and then // add the cache item.HitPage();}/// <summary>/// Hits a local webpage in order to add another expiring item in cache/// </summary>private void HitPage(){WebClient client = new WebClient();client.DownloadData(DummyPageUrl);}/// <summary>/// Asynchronously do the 'service' works/// </summary>private void DoWork(){Debug.WriteLine("Begin DoWork...");Debug.WriteLine("Running as: " WindowsIdentity.GetCurrent().Name );DoSomeFileWritingStuff();DoSomeDatabaseOperation();DoSomeEmailSendStuff();DoSomeMSMQStuff();ExecuteQueuedJobs();Debug.WriteLine("End DoWork...");}/// <summary>/// Execute jobs that are queued for execution at a specific time/// </summary>private void ExecuteQueuedJobs(){ArrayList jobs = new ArrayList();// Collect which jobs are overdueforeach( Job job in _JobQueue ){if( job.ExecutionTime <= DateTime.Now )jobs.Add( job );}// Eecute the jobs that are overdueforeach( Job job in jobs ){lock( _JobQueue ){_JobQueue.Remove( job );}job.Execute();}}/// <summary>/// Test file write. Make sure the path allows ASPNET or NETWORK SERVICE account/// to write /// </summary>private void DoSomeFileWritingStuff(){Debug.WriteLine("Writing to file...");try{using( StreamWriter writer = new StreamWriter(LOG_FILE, true) ){writer.WriteLine("Cache Callback: {0}", DateTime.Now);writer.Close();}}catch( Exception x ){Debug.WriteLine( x );}Debug.WriteLine("File write successful");}/// <summary>/// Test database connectivity/// </summary>private void DoSomeDatabaseOperation(){Debug.WriteLine("Connecting to database...");using( SqlConnection con = new SqlConnection(CONNECTION_STRING) ){con.Open();using( SqlCommand cmd = new SqlCommand( "INSERT INTO ASPNETServiceLog VALUES (@Message, @DateTime)", con ) ){cmd.Parameters.Add("@Message", SqlDbType.VarChar, 1024).Value = "Hi I'm the ASP NET Service";cmd.Parameters.Add("@DateTime", SqlDbType.DateTime).Value = DateTime.Now;cmd.ExecuteNonQuery();}con.Close();}Debug.WriteLine("Database connection successful");} /// <summary>/// Test email send/// </summary>private void DoSomeEmailSendStuff(){try{MailMessage msg = new MailMessage();msg.From = "abc@cde.fgh";msg.To = "ijk@lmn.opq";msg.Subject = "Reminder: " DateTime.Now.ToString();msg.Body = "This is a server generated message";SmtpMail.Send( msg );}catch( Exception x ){Debug.WriteLine( x );}}/// <summary>/// Test MSMQ/// </summary>private void DoSomeMSMQStuff(){using( MessageQueue queue = new MessageQueue(MSMQ_NAME) ){queue.Send(DateTime.Now);queue.Close();}}protected void Session_Start(Object sender, EventArgs e){}protected void Application_BeginRequest(Object sender, EventArgs e){// If the dummy page is hit, then it means we want to add another item// in cacheif( HttpContext.Current.Request.Url.ToString() == DummyPageUrl ){// Add the item in cache and when succesful, do the work.RegisterCacheEntry();}}protected void Application_EndRequest(Object sender, EventArgs e){}protected void Application_AuthenticateRequest(Object sender, EventArgs e){}protected void Application_Error(Object sender, EventArgs e){Debug.WriteLine( Server.GetLastError() );}protected void Session_End(Object sender, EventArgs e){}protected void Application_End(Object sender, EventArgs e){}#region Web Form Designer generated code/// <summary>/// Required method for Designer support - do not modify/// the contents of this method with the code editor./// </summary>private void InitializeComponent(){ this.components = new System.ComponentModel.Container();}#endregion}}