而在Asp.Net Forums中有很好的例子，定时器应用如下：
1. 更新论坛统计信息
2. 定时索引指定条数的帖子
3. 定时群发队列中的邮件
Forums中对定时器的调用是放在自定义HttpModule的Init方法中（如果您没有使用HttpModule，也可以在Globals.aspx中的Application_OnStart 中调用定时器）。
| // 定时器 static Timer statsTimer; static Timer emailTimer; // 定时间隔 private long EmailInterval = ForumConfiguration.GetConfig().ThreadIntervalEmail * 60000; private long StatsInterval = ForumConfiguration.GetConfig().ThreadIntervalStats * 60000; public String ModuleName { get { return "ForumsHttpModule"; } } // ********************************************************************* // ForumsHttpModule // /**//// <summary> /// Initializes the HttpModule and performs the wireup of all application /// events. /// </summary> /// <param name="application">Application the module is being run for</param> public void Init(HttpApplication application) { // Wire-up application events // // 略去其他代码 ForumConfiguration forumConfig = ForumConfiguration.GetConfig(); // 如果使用定时器并且定时器还没初始化 if( forumConfig != null && forumConfig.IsBackgroundThreadingDisabled == false ) { if (emailTimer == null) // 新建定时器 // 新建一个TimerCallback委托，具体要执行的方法在ScheduledWorkCallbackEmailInterval中 emailTimer = new Timer(new TimerCallback(ScheduledWorkCallbackEmailInterval), application.Context, EmailInterval, EmailInterval); if( forumConfig.IsIndexingDisabled == false && statsTimer == null ) { statsTimer = new Timer(new TimerCallback(ScheduledWorkCallbackStatsInterval), application.Context, StatsInterval, StatsInterval); } } } /**//// <summary> /// 释放定时器 /// </summary> public void Dispose() { statsTimer = null; emailTimer = null; } Timer Callbacks#region Timer Callbacks /**//// <summary> /// 定时发送队列中待发送的邮件 /// </summary> private void ScheduledWorkCallbackEmailInterval (object sender) { try { // 当处理邮件时暂停定时器 emailTimer.Change( System.Threading.Timeout.Infinite, EmailInterval ); // 发送队列中的邮件 // Emails.SendQueuedEmails( (HttpContext) sender); // 更新匿名用户 // Users.UpdateAnonymousUsers( (HttpContext) sender); } catch( Exception e ) { ForumException fe = new ForumException( ForumExceptionType.EmailUnableToSend, "Scheduled Worker Thread failed.", e ); fe.Log(); } finally { // 重新启动定时器 emailTimer.Change( EmailInterval, EmailInterval ); } } /**//// <summary> /// 定时索引帖子和定时更新论坛统计信息 /// </summary> private void ScheduledWorkCallbackStatsInterval(object sender) { try { // 休眠定时器 statsTimer.Change( System.Threading.Timeout.Infinite, StatsInterval ); // 每次索引100篇帖子 // Search.IndexPosts( (HttpContext) sender, 100); // 更新论坛统计信息 SiteStatistics.LoadSiteStatistics( (HttpContext) sender, true, 1 ); } catch( Exception e ) { ForumException fe = new ForumException( ForumExceptionType.UnknownError, "Failure performing scheduled statistics maintenance.", e ); fe.Log(); } finally { // 唤醒定时器 statsTimer.Change( StatsInterval, StatsInterval); } } #endregion |