原文:
http://blog.joycode.com/dotey/archive/2004/12/20/41438.aspx
asp.net forums中定时器的应用
在Asp.Net中使用定时器,破宝之前已有Blog写过《在 ASP.NET 中使用计时器(Timer)》,这里主要针对Asp.Net Forums来说一下其具体实现。
在Asp.Net Forums中,对定时器有如下应用:
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
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
其实稍加改进就可以应用到我们自己的项目中,例如前不久刚做一个项目,因为数据量过于庞大,每次从数据库取非常慢,然后改成使用定时器,每隔12小时将最新的数据列表生成静态的文本。
BTW: 有技术八股文之嫌哦:P
分类:
8.技术转载区
本文转自浪子博客园博客,原文链接:http://www.cnblogs.com/walkingboy/archive/2005/04/14/137748.html,如需转载请自行联系原作者