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  对于CS的分析你可以能会从页面开始,其实那并不是一个很好的方法,因为CS采用了MasterPage和内建的ThemeSkins,页面一层嵌套一层,如果你对CS页面执行机制不了解,或者你是初学者,这个时候可能就会碰壁,接着就放弃了对CS更深入的了解。我希望我的专题能从CS的运行过程开始一步一步地讲解,同时把ASP.NET的运行机理也表述出来,因此学习了解CS的过程就是对ASP.NET深入了解得过程。当然,我个人的开发经验与水平也是有限的,如果在专题中表述有问题,或者有疑问可以直接在文章的评论中直接指出,我将万分感谢你。

在分析CSHttpModule.cs的时候,你会看到这样两句代码:

CSEvents.UserKnown(csContext.User);

CSEvents.CSException(csException);

其实短短两行代码后面隐藏了DelegatesEvents的大量运用,CS也通过这样的运用实现了一种模块化的处理机制,即CSModules

打开CommunityServerWeb项目下的communityserver.config文件,这是CS的配置文件(Web.config不同,communityserver.config主要配置的是CS内部的一些运行机制,而Web.config主要配置的是与Asp.net的交互)。找到文件中的这段:

<CSModules>

              <add name = "CSMembershipRulesModule" type = "CommunityServer.Components.CSMembershipRulesModule, CommunityServer.Components" />

              <add name = "CSCatastrophicExceptionModule" type = "CommunityServer.Components.CSCatastrophicExceptionModule, CommunityServer.Components" />

        <add name = "CSExceptionModule" type = "CommunityServer.Components.CSExceptionModule, CommunityServer.Components" />

              <add name = "IrcCommands" type = "CommunityServer.Discussions.Components.IrcCommandsModule, CommunityServer.Discussions" />

              <add name = "ForumCensorship" type = "CommunityServer.Discussions.Components.CensorshipModule, CommunityServer.Discussions" />

              <add name = "ForumEmoticon" type = "CommunityServer.Discussions.Components.EmoticonModule, CommunityServer.Discussions" />

              <add name = "ForumSourceCode" type = "CommunityServer.Discussions.Components.SourceCodeModule, CommunityServer.Discussions" />

              <add name = "ForumHtmlScrubbing" type = "CommunityServer.Discussions.Components.HtmlScrubbingModule, CommunityServer.Discussions" />

              <add name = "BBcodeToHtml" type = "CommunityServer.Discussions.Components.BBcodeToHtmlModule, CommunityServer.Discussions" />

              <add name = "ForumPlainText" type = "CommunityServer.Discussions.Components.PlainTextModule, CommunityServer.Discussions" />

    

              <add name = "WeblogCensorModule" type = "CommunityServer.Blogs.Components.CensorModule, CommunityServer.Blogs" />

              <add name = "WeblogPostandArticleHtmlScrubbing" type = "CommunityServer.Blogs.Components.PostandArticleHtmlScrubbing, CommunityServer.Blogs" />

              <add name = "WeblogFeedbackHtmlFormatting" type = "CommunityServer.Blogs.Components.FeedbackHtmlFormatting, CommunityServer.Blogs" />

              <add name = "TrackbackModule" type = "CommunityServer.Blogs.Components.TrackbackModule, CommunityServer.Blogs" />

              <add name = "XmlRpcPingModule" type = "CommunityServer.Blogs.Components.XmlRpcPingModule, CommunityServer.Blogs" />

              <add name = "WeblogFormattingModule" type = "CommunityServer.Blogs.Components.WeblogFormattingModule, CommunityServer.Blogs" />

              <add name = "PictureCensor" type = "CommunityServer.Galleries.Components.CensorPictureModule, CommunityServer.Galleries" />

              <add name = "PictureHtmlScrubber" type = "CommunityServer.Galleries.Components.HtmlScrubberModule, CommunityServer.Galleries" />

              <add name = "PictureComments" type = "CommunityServer.Galleries.Components.CommentModule, CommunityServer.Galleries" />

              <!-- <add name = "MaxPictureSize" type = "CommunityServer.Galleries.Components.MaxPictureSizeModule, CommunityServer.Galleries" maxWidth="1024" maxHeight="768" quality="90" /> -->

         </CSModules>

我们拿出其中的一个来分析运行过程,例:

     <add name = "CSExceptionModule" type = "CommunityServer.Components.CSExceptionModule, CommunityServer.Components" />

这是CS中异常处理的模块,当发生异常的时候该模块将调用一个RedirectToMessage方法,提示一个友好的错误界面,告诉请求的用户有错误发生。那么CS系统是如何在发生错误的时候自动调用RedirectToMessage方法转向另外一个页面提示友好错误的呢?先打开CommunityServerComponents项目下Components文件夹中的CSApplication.cs

 

using System;

using System.Collections;

using System.ComponentModel;

using System.Web.Caching;

using System.Xml;

using CommunityServer.Configuration;

 

namespace CommunityServer.Components

{

 

     #region Delegates

     //Do we want one single delegate or a custom one for each type

     //public delegate void CSEventHandler(object sender, CSEventArgs e);

     public delegate void CSUserEventHandler(User user, CSEventArgs e);

     public delegate void CSPostEventHandler(Post post, CSEventArgs e);

     public delegate void CSSectionEventHandler(Section section, CSEventArgs e);

     public delegate void CSGroupEventHandler(Group group, CSEventArgs e);

     public delegate void CSExceptionHandler(CSException csEx, CSEventArgs e);

     #endregion

 

     /// <summary>

     /// Summary description for CSApplication.

     /// </summary>

     public class CSApplication

     {

         #region private members

         private EventHandlerList Events = new EventHandlerList();

         private static readonly object sync = new object();

         private Hashtable modules = new Hashtable();

         #endregion

 

         #region Event Keys (static)

         private static object EventAuthorizePost = new object();

         private static object EventPrePostUpdate = new object();

         private static object EventPreProcessPost = new object();

         private static object EventPostPostUpdate = new object();

         private static object EventRatePost = new object();

         //private static object EventPreRenderPost = new object();

 

         private static object EventPreUserUpdate = new object();

         private static object EventPostUserUpdate = new object();

         private static object EventUserRemove = new object();

         private static object EventUserKnown = new object();

         private static object EventUserValidated = new object();

 

         private static object EventPreSectionUpdate = new object();

         private static object EventPostSectionUpdate = new object();

 

         private static object EventPreSectionGroupUpdate = new object();

         private static object EventPostSectionGroupUpdate = new object();

 

         private static object EventUnhandledException = new object();

         #endregion

 

         #region cnstr

         private CSApplication()

         {

         }

 

         internal static CSApplication Instance()

         {

              const string key = "CSApplication";

              CSApplication app = CSCache.Get(key) as CSApplication;

              if(app == null)

              {

                   lock(sync)

                   {

                       app = CSCache.Get(key) as CSApplication;

                       if(app == null)

                       {

                            CSConfiguration config = CSContext.Current.Config;

 

                            XmlNode node = config.GetConfigSection("CommunityServer/CSModules");

                            app = new CSApplication();

                            if(node != null)

                            {

                                 foreach(XmlNode n in node.ChildNodes)

                                 {

                                     if(n.NodeType != XmlNodeType.Comment)

                                     {

                                          switch(n.Name)

                                          {

                                               case "clear":

                                                   app.modules.Clear();

                                                   break;

                                               case "remove":

                                                   app.modules.Remove(n.Attributes["name"].Value);

                                                   break;

                                               case "add":

                                              

                                                   string name = n.Attributes["name"].Value;

                                                   string itype = n.Attributes["type"].Value;

 

                                                   Type type = Type.GetType(itype);

 

                                                   if(type == null)

                                                        throw new Exception(itype + " does not exist");

 

                                                   ICSModule mod = Activator.CreateInstance(type) as ICSModule;

 

                                                   if(mod == null)

                                                        throw new Exception(itype + " does not implement ICSModule or is not configured correctly");

 

                                                   mod.Init(app, n);

                                                   app.modules.Add(name,mod);

 

 

                                                   break;

 

                                          }

                                     }

                                 }

                            }

                            CacheDependency dep = new CacheDependency(null, new string[]{CSConfiguration.CacheKey});

                            CSCache.Max(key, app,dep);

                       }

 

                      

                   }

              }

              return app;

         }

         #endregion

 

         #region Post Events

 

         #region Execute Events

 

         internal void ExecuteAuthorizePost()

         {

              ExecuteUserEvent(EventAuthorizePost,CSContext.Current.User);

         }

 

         internal void ExecutePrePostEvents(Post post, ObjectState state, ApplicationType appType)

         {

              ExecutePostEvent(EventPreProcessPost,post,state,appType);

         }

 

         internal void ExecutePrePostUpdateEvents(Post post, ObjectState state, ApplicationType appType)

         {

              ExecutePostEvent(EventPrePostUpdate,post,state,appType);

         }

 

         internal void ExecutePostPostUpdateEvents(Post post, ObjectState state, ApplicationType appType)

         {

              ExecutePostEvent(EventPostPostUpdate,post,state,appType);

         }

 

         internal void ExecuteRatePostEvents(Post post, ApplicationType appType)

         {

              ExecutePostEvent(EventRatePost,post,ObjectState.None,appType);

         }

 

//       internal void ExecutePrePostRender(Post post, ApplicationType appType)

//       {

//            ExecutePostEvent(EventPreRenderPost,post,ObjectState.None,appType);

//       }

 

         protected void ExecutePostEvent(object EventKey, Post post,ObjectState state, ApplicationType appType)

         {

              CSPostEventHandler handler = Events[EventKey] as CSPostEventHandler;

              if (handler != null)

              {

                   handler(post, new CSEventArgs(state,appType));

              }

         }

 

         #endregion

 

         #region Events

         /// <summary>

         /// Event raised before a user accesses a page which can be used to create content

         /// </summary>

         public event CSUserEventHandler AuthorizePost

         {

              add{Events.AddHandler(EventAuthorizePost, value);}

              remove{Events.RemoveHandler(EventAuthorizePost, value);}

         }

 

         /// <summary>

         /// Event raised before any post processing takes place

         /// </summary>

         public event CSPostEventHandler PreProcessPost

         {

              add{Events.AddHandler(EventPreProcessPost, value);}

              remove{Events.RemoveHandler(EventPreProcessPost, value);}

         }

 

         /// <summary>

         /// Fires after PreProcessPost but before the post change is commited to the datastore

         /// </summary>

         public event CSPostEventHandler PrePostUpdate

         {

              add{Events.AddHandler(EventPrePostUpdate, value);}

              remove{Events.RemoveHandler(EventPrePostUpdate, value);}

         }

 

         /// <summary>

         /// Fires after a post change is commited to the datastore

         /// </summary>

         public event CSPostEventHandler PostPostUpdate

         {

              add{Events.AddHandler(EventPostPostUpdate, value);}

              remove{Events.RemoveHandler(EventPostPostUpdate, value);}

         }

 

         /// <summary>

         /// Fires after a Post or Thread is rated

         /// </summary>

         public event CSPostEventHandler RatePost

         {

              add{Events.AddHandler(EventRatePost, value);}

              remove{Events.RemoveHandler(EventRatePost, value);}

         }

 

//       /// <summary>

//       /// Event raised before an individual post is rendered

//       /// </summary>

//       public event CSPostEventHandler PreRenderPost

//       {

//            add{Events.AddHandler(EventPreRenderPost, value);}

//            remove{Events.RemoveHandler(EventPreRenderPost, value);}

//       }

 

         #endregion

 

         #endregion

 

         #region User Events

 

         #region Execute Events

        

         internal void ExecuteUserValidated(User user)

         {

              ExecuteUserEvent(EventUserValidated,user);

         }

 

         internal void ExecuteUserKnown(User user)

         {

              ExecuteUserEvent(EventUserKnown,user);

         }

 

         internal void ExecutePreUserUpdate(User user, ObjectState state)

         {

              ExecuteUserEvent(EventPreUserUpdate,user,state,ApplicationType.Unknown);

         }

 

         internal void ExecutePostUserUpdate(User user, ObjectState state)

         {

              ExecuteUserEvent(EventPostUserUpdate,user,state,ApplicationType.Unknown);

         }

 

         internal void ExecuteUserRemove(User user)

         {

              ExecuteUserEvent(EventUserRemove,user,ObjectState.Delete,ApplicationType.Unknown);

         }

 

         protected void ExecuteUserEvent(object EventKey, User user)

         {

              ExecuteUserEvent(EventKey,user,ObjectState.None,ApplicationType.Unknown);

         }

         protected void ExecuteUserEvent(object EventKey, User user,ObjectState state, ApplicationType appType)

         {

              CSUserEventHandler handler = Events[EventKey] as CSUserEventHandler;

              if (handler != null)

              {

                   handler(user, new CSEventArgs(state,appType));

              }

         }

 

         #endregion

 

         #region Events

 

         /// <summary>

         /// Fires after a user's credentials have been validated.

         /// </summary>

         public event CSUserEventHandler UserValidated

         {

              add{Events.AddHandler(EventUserValidated, value);}

              remove{Events.RemoveHandler(EventUserValidated, value);}

         }

 

         /// <summary>

         /// Fires once the current user has been identified. This user may still be anonymous.

         /// </summary>

         public event CSUserEventHandler UserKnown

         {

              add{Events.AddHandler(EventUserKnown, value);}

              remove{Events.RemoveHandler(EventUserKnown, value);}

         }

 

         /// <summary>

         /// Fires before a User is saved/updated to the datastore

         /// </summary>

         public event CSUserEventHandler PreUserUpdate

         {

              add{Events.AddHandler(EventPreUserUpdate, value);}

              remove{Events.RemoveHandler(EventPreUserUpdate, value);}

         }

 

         /// <summary>

         /// Fires after a User is saved/updated to the datastore

         /// </summary>

         public event CSUserEventHandler PostUserUpdate

         {

              add{Events.AddHandler(EventPostUserUpdate, value);}

              remove{Events.RemoveHandler(EventPostUserUpdate, value);}

         }

 

         /// <summary>

         /// Fires before a User is removed from the datastore.

         /// </summary>

         public event CSUserEventHandler UserRemove

         {

              add{Events.AddHandler(EventUserRemove, value);}

              remove{Events.RemoveHandler(EventUserRemove, value);}

         }

 

         #endregion

 

         #endregion

 

         #region Section Events

 

         internal void ExecutePreSectionUpdate(Section section, ObjectState state, ApplicationType appType)

         {

              CSSectionEventHandler handler = Events[EventPreSectionUpdate] as CSSectionEventHandler;

              if (handler != null)

              {

                   handler(section, new CSEventArgs(state,appType));

              }

         }

 

         internal void ExecutePostSectionUpdate(Section section, ObjectState state, ApplicationType appType)

         {

              CSSectionEventHandler handler = Events[EventPostSectionUpdate] as CSSectionEventHandler;

              if (handler != null)

              {

                   handler(section, new CSEventArgs(state,appType));

              }

         }

 

 

         /// <summary>

         /// Event raised before a section change is committed to the datastore (create/update)

         /// </summary>

         public event CSSectionEventHandler PreSectionUpdate

         {

              add{Events.AddHandler(EventPreSectionUpdate, value);}

              remove{Events.RemoveHandler(EventPreSectionUpdate, value);}

         }

 

 

         /// <summary>

         /// Event raised after a section chage is committed to the data store

         /// </summary>

         public event CSSectionEventHandler PostSectionUpdate

         {

              add{Events.AddHandler(EventPostSectionUpdate, value);}

              remove{Events.RemoveHandler(EventPostSectionUpdate, value);}

         }

 

         #endregion

 

         #region Group Events

 

         internal void ExecutePreSectionGroupUpdate(Group group, ObjectState state, ApplicationType appType)

         {

              CSGroupEventHandler handler = Events[EventPreSectionGroupUpdate] as CSGroupEventHandler;

              if (handler != null)

              {

                   handler(group, new CSEventArgs(state,appType));

              }

         }

 

         internal void ExecutePostSectionGroupUpdate(Group group, ObjectState state, ApplicationType appType)

         {

              CSGroupEventHandler handler = Events[EventPostSectionGroupUpdate] as CSGroupEventHandler;

              if (handler != null)

              {

                   handler(group, new CSEventArgs(state,appType));

              }

         }

 

         /// <summary>

         /// Event raised before a group chage is committed to the datastore (create/update)

         /// </summary>

         public event CSGroupEventHandler PreSectionGroupUpdate

         {

              add{Events.AddHandler(EventPreSectionGroupUpdate, value);}

              remove{Events.RemoveHandler(EventPreSectionGroupUpdate, value);}

         }

 

         /// <summary>

         /// Event raised after a group chage is committed to the data store

         /// </summary>

         public event CSGroupEventHandler PostSectionGroupUpdate

         {

              add{Events.AddHandler(EventPostSectionGroupUpdate, value);}

              remove{Events.RemoveHandler(EventPostSectionGroupUpdate, value);}

         }

 

         #endregion

 

         #region Exceptions

         /// <summary>

         /// Event raised before a group chage is committed to the datastore (create/update)

         /// </summary>

         public event CSExceptionHandler CSException

         {

              add{Events.AddHandler(EventUnhandledException, value);}

              remove{Events.RemoveHandler(EventUnhandledException, value);}

         }

 

         internal void ExecuteCSExcetion(CSException csEx)

         {

              CSExceptionHandler handler = Events[EventUnhandledException] as CSExceptionHandler;

              if (handler != null)

              {

                   handler(csEx,new CSEventArgs());

              }

         }

 

         #endregion

 

     }

}

 

文件太长,我们抓出关键的部分来分析:

public delegate void CSExceptionHandler(CSException csEx, CSEventArgs e);

这里先申明一个委托,相当于一个函数指针。在通俗一点理解它就是一个跑腿的,专管传递对象与对象间的调用信息。

接下来:

internal static CSApplication Instance()

         {

              const string key = "CSApplication";

              CSApplication app = CSCache.Get(key) as CSApplication;

              if(app == null)

              {

                   lock(sync)

                   {

                       app = CSCache.Get(key) as CSApplication;

                       if(app == null)

                       {

                            CSConfiguration config = CSContext.Current.Config;

 

                            XmlNode node = config.GetConfigSection("CommunityServer/CSModules");

                            app = new CSApplication();

                            if(node != null)

                            {

                                 foreach(XmlNode n in node.ChildNodes)

                                 {

                                     if(n.NodeType != XmlNodeType.Comment)

                                     {

                                          switch(n.Name)

                                          {

                                               case "clear":

                                                   app.modules.Clear();

                                                   break;

                                               case "remove":

                                                   app.modules.Remove(n.Attributes["name"].Value);

                                                   break;

                                               case "add":

                                              

                                                   string name = n.Attributes["name"].Value;

                                                   string itype = n.Attributes["type"].Value;

 

                                                   Type type = Type.GetType(itype);

 

                                                   if(type == null)

                                                        throw new Exception(itype + " does not exist");

 

                                                   ICSModule mod = Activator.CreateInstance(type) as ICSModule;

 

                                                   if(mod == null)

                                                        throw new Exception(itype + " does not implement ICSModule or is not configured correctly");

 

                                                   mod.Init(app, n);

                                                   app.modules.Add(name,mod);

 

 

                                                   break;

 

                                          }

                                     }

                                 }

                            }

                            CacheDependency dep = new CacheDependency(null, new string[]{CSConfiguration.CacheKey});

                            CSCache.Max(key, app,dep);

                       }

 

                      

                   }

              }

              return app;

         }

这段很重要,通过读取communityserver.config文件的<CSModules>,初始化每个CSModule,注意,初始化后并且调用了这些CSModule中的Init方法。具体看看这些Module中的Init都做了什么,打开CommunityServerComponents项目下的Components文件夹中的CSExceptionModule.cs

//------------------------------------------------------------------------------

// <copyright company="Telligent Systems">

//     Copyright (c) Telligent Systems Corporation. All rights reserved.

// </copyright>

//------------------------------------------------------------------------------

 

using System;

using System.Web;

 

namespace CommunityServer.Components

{

     /// <summary>

     /// Summary description for CSExceptionModule.

     /// </summary>

     public class CSExceptionModule : ICSModule

     {

         public CSExceptionModule()

         {

              //

              // TODO: Add constructor logic here

              //

         }

          #region ICSModule Members

 

         public void Init(CSApplication csa, System.Xml.XmlNode node)

         {

              csa.CSException +=new CSExceptionHandler(csa_CSException);

         }

 

         #endregion

 

         private void csa_CSException(CSException csEx, CSEventArgs e)

         {

              CSContext csContext = CSContext.Current;

 

              if (csEx.ExceptionType != CSExceptionType.UnknownError && csContext.IsWebRequest)

              {

                   RedirectToMessage(csContext.Context, csEx);

              }

         }

 

         private static void RedirectToMessage (HttpContext context, CSException exception)

         {

 

              if ((exception.InnerException != null) && ( exception.InnerException is CSException))

              {

                   CSException inner = (CSException) exception.InnerException;

              }

              context.Response.Redirect(Globals.GetSiteUrls().Message( exception.ExceptionType ), true);

         }

 

     }

}

哈哈,原来在Init方法里把一个CSExceptionHandler委托添加到CSException事件上,这个委托指向csa_CSException方法,还是通俗点说:如果CSException这个事件发生了,CSExceptionHandler这个跑腿的委托就会马上告诉csa_CSException方法要他执行,如果事件没有被激发就什么也不做。

名词: event 关键字使您得以指定当代码中的某些“事件”发生时调用的委托。此委托可以有一个或多个关联的方法,当代码指示该事件已发生时将调用关联的方法。

 

那么这个CSException又是怎么回事?在哪里定义的?我们回到CSApplication.cs文件中,看样几行:

         public event CSExceptionHandler CSException

         {

              add{Events.AddHandler(EventUnhandledException, value);}

              remove{Events.RemoveHandler(EventUnhandledException, value);}

     }

这里定义了一个CSException事件,而事件发生的时候只能用CSExceptionHandler这个委托来做跑腿的。其实CS中是把委托都存放在了一个EventHandlerList中,因此此处你可以看到addremove, 这是访问器的声明,用于添加或移除客户代码中的事件处理程序,这样做的好处是公开大量的事件但不为每个事件分配字段,而是使用EventHandlerList存储这些事件实例。为了理解事件的调用执行过程,我们还必须看几个文件:CSEvents.csCSEventArgs.cs

CSEventArgs.cs存储事件的数据,这个很好理解,它继承自EventArgs。当事件发生时CSEventArgs用来传递事件的信息,这里传递两个值:ObjectStateApplicationType(可以在Enumerations文件夹下找到这两个枚举的内容)

CSEvents.cs这是对事件调用的一个包装器,看异常处理的包装:

         public static void CSException(CSException csEx)

         {

              CSApplication.Instance().ExecuteCSExcetion(csEx);

          }

这里先调用CSApplication.Instance()方法,实例化一个CSApplication对象,如果你是第一次调用Instance()方法,就实例化所有在<CSModules>中配置的类,并且调用他们的Init方法(CSModules中配置的这些类,都实现了ICSModule接口,而这个接口要求继承他的类都具备Init方法),执行Init方法的目的就是把委托添加到事件上,使委托指向的方法可以在事件触发的时候被调用。实例化后再调用ExecuteCSExcetion方法并且传递CSException的实例,ExecuteCSExcetion方法如下:

         internal void ExecuteCSExcetion(CSException csEx)

         {

              CSExceptionHandler handler = Events[EventUnhandledException] as CSExceptionHandler;

              if (handler != null)

              {

                   handler(csEx,new CSEventArgs());

              }

         }

先通过对EventHandlerList索引访问,即Events[EventUnhandledException],从列表中找到这个CSExceptionHandler事件,如果不为null就执行它。EventUnhandledException又是什么,其实这只是一个Key,用来标示存储的事件。

 

有必要总结一下,不然你会被这种调用来调用去的关系搞得一头雾水,

 

      

 

以异常处理为例:

1:在错误发生后,调用Application_OnError方法;

2:在方法的最后调用CSEvents.CSException(csException)

3:进入CSEvents包装器,调用CSApplication.Instance().ExecuteCSExcetion(csEx);

4:执行CSApplication.Instance()方法,如果是第一次执行就根据communityserver.config文件中的配置,把所有的CSModules实例化,并且调用ICSModule接口类中的Init方法,然后缓存这些实例化的类(如果是第二次访问就从缓存中读取)

5:在实现ICSModule接口的类中,如CSExceptionModule.csInit方法是给事件添加委托的过程,这个过程中实现了委托指向的一个或者多个方法与事件进行关联,异常处理的方法csa_CSException(CSException csEx, CSEventArgs e)就是在这里被关联到异常事件上的。

6:经过上面几步后,CS系统接着调用ExecuteCSExcetion方法,在ExecuteCSExcetion方触发了CSException事件

7CSException事件被触发后,就执行事件中委托所指向的函数,这里是CSExceptionModule.cs文件中的private void csa_CSException(CSException csEx, CSEventArgs e)

 

CS如此大量的使用DelegatesEvents带来了什么,也许你会认为它这样是把问题复杂化,而且觉得这非常没有必要,完全可以在异常处理的最后调用处理方法即可,何必通过事件来回周转!最后说明一下这样做的重要性:

1:通过事件使调用方法者与方法本身隔离,如在CSHttpModule.cs文件中的Application_OnError方法触发CSEvents.CSException事件,而事件要做些什么处理,需要调用什么方法Application_OnError根本不知道。如果你要改变CSEvents.CSException事件处理方法的结构,甚至十处理方法的名称,Application_OnError也不需要改动,因为他根本不关心具体的实现,它的任务只是触发这个事件。

2:如果你想一个方法调用多个方法,普通的做法就是在方法中一次调用或者在方法中嵌套调用。这样做并不是一个好的设计模式,而事件可以通过委托调用多个委托指向的方法(在异常处理中只指向了一个方法,当然你可以指向任意N个方法),而这种调用也是相互隔离的,被调用的方法并不致到谁调用它,而调用者也不关心它调用谁。

3:模块化,你的代码直接没有非常的多紧密联系,而是通过事件来通知处理方法,在CS中又加入了xml的配置文件,使得这样的模块化更突出,你设置可以把处理异常的类单独编译在一个dll中。

好处还有很多

 

CS中,对Post内容的不良信息过滤也是同过这样的机制完成的,允许的过程基本一致,只是调用不同的事件处理方法,你可以自己分析。

posted on 2006-06-02 15:25 阿昆 阅读(...) 评论(...) 编辑 收藏