把CommunityServer的事件框架应用到当前的项目中，可以在一个方法调用中设置其前置和后置事件，从而把一个额外的业务处理外置到别的模块中进行独立处理。
1、需要定义一系列的委托，如public delegate void PSPRoleEventHandler(PRole pRole, PSEventArgs e);委托参数的定义决定以后事件的参数，这里的PSEventArgs用于表示一些通用的参数传入，例如ObjectState针对对象操作的状态。
public enum ObjectState
{
Create,
Update,
Delete,
None,
Runtime
} public class PSEventArgs : EventArgs
{
private ObjectState _state;
public ObjectState State
{
get { return _state; }
}
public PSEventArgs(ObjectState state)
{
_state = state;
}
public PSEventArgs() : this(ObjectState.None) { }
}
2、创建PSApplication类，用于统一定义一些事件，并从配置文件的模块配置加载这些事件的真实调用，以下为一下例子：
public class PSApplication
{
private members#region private members
private EventHandlerList Events = new EventHandlerList();
private static readonly object sync = new object();
private Hashtable modules = new Hashtable();
#endregion
Event Keys (static)#region Event Keys (static)
private static object EventPrePRoleUpdate = new object();
private static object EventPRoleUpdate = new object();
#endregion
cnstr#region cnstr
private PSApplication() { }
internal static PSApplication Instance()
{
const string key = "PSApplication";
HttpContext context = HttpContext.Current;
PSApplication app = context.Cache[key] as PSApplication;
if (app == null)
{
lock (sync)
{
app = context.Cache[key] as PSApplication;
if (app == null)
{
PSConfiguration config = PSConfiguration.GetConfig();
XmlNode node = config.GetConfigSection("Configurations/PSModules");
app = new PSApplication();
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":
XmlAttribute removeNameAtt = n.Attributes["name"];
string removeName = removeNameAtt == null ? null : removeNameAtt.Value;
if (!String.IsNullOrEmpty(removeName) && app.modules.ContainsKey(removeName))
{
app.modules.Remove(removeName);
}
break;
case "add":
XmlAttribute en = n.Attributes["enabled"];
if (en != null && en.Value == "false")
continue;
XmlAttribute nameAtt = n.Attributes["name"];
XmlAttribute typeAtt = n.Attributes["type"];
string name = nameAtt == null ? null : nameAtt.Value;
string itype = typeAtt == null ? null : typeAtt.Value;
if (String.IsNullOrEmpty(name))
{
//EventLogs.Warn("");
continue;
}
if (String.IsNullOrEmpty(itype))
{
//EventLogs.Warn("");
continue;
}
Type type = Type.GetType(itype);
if (type == null)
{
//EventLogs.Warn("");
continue;
}
IPSModule mod = Activator.CreateInstance(type) as IPSModule;
if (mod == null)
{
//EventLogs.Warn("");
continue;
}
mod.Init(app, n);//注意，通过Configurations/PSModules/[Model]/add节的配置可以传递一些扩展的配置
app.modules.Add(name, mod);
break;
}
}
}
}
//以PSConfiguration的CacheKey为依赖项，即PSConfiguration的缓存过期，则本缓存也会过期
CacheDependency dep = new CacheDependency(null, new string[] { PSConfiguration.CacheKey });
context.Cache.Insert(key, app, dep);
}
}
}
return app;
}
#endregion
PRole Events#region PRole Events
internal void ExecutePrePRoleUpdate(PRole pRole, ObjectState state)
{
PSPRoleEventHandler handler = Events[EventPrePRoleUpdate] as PSPRoleEventHandler;
if (handler != null)
{
handler(pRole, new PSEventArgs(state));
}
}
internal void ExecutePRoleUpdate(PRole pRole, ObjectState state)
{
PSPRoleEventHandler handler = Events[EventPRoleUpdate] as PSPRoleEventHandler;
if (handler != null)
{
handler(pRole, new PSEventArgs(state));
}
}
/**//// <summary>
/// 触发事件，在PRole数据保存到数据库之前
/// </summary>
public event PSPRoleEventHandler PrePRoleUpdate
{
add { Events.AddHandler(EventPrePRoleUpdate, value); }
remove { Events.RemoveHandler(EventPrePRoleUpdate, value); }
}
/**//// <summary>
/// 触发事件，在PRole数据保存到数据库之后
/// </summary>
public event PSPRoleEventHandler PRoleUpdate
{
add { Events.AddHandler(EventPRoleUpdate, value); }
remove { Events.RemoveHandler(EventPRoleUpdate, value); }
}
#endregion
}
其中的internal static PSApplication Instance()方法用于实例化PSApplication对象并从配置文件中加载事件真实实现的模块信息，例如模块配置可以写成这样：
<Configurations>
<PSModules>
<add name="PRoleModule" type="CSDN.PermissionService.Components.PRoleModule, CSDN.PermissionService.Components" />
</PSModules>
</Configurations>
这样通过组件CSDN.PermissionService.Components中的CSDN.PermissionService.Components.PRoleModule模块就可以加载对角色操作的一些前后事件的功能
public event PSPRoleEventHandler PrePRoleUpdate 添加或移除在PRole数据保存到数据库之前的触发事件
public event PSPRoleEventHandler PRoleUpdate 添加或移除在PRole数据保存到数据库之后的触发事件
private EventHandlerList Events = new EventHandlerList(); 用于保存一下委托的事件列表
对于模块设计需要定实现一个IPSModule接口
public interface IPSModule
{
void Init(PSApplication psa, XmlNode node);
}
例如：PRoleModule
public class PRoleModule : IPSModule
{
public void Init(PSApplication psa, System.Xml.XmlNode node)
{
psa.PrePRoleUpdate += new PSPRoleEventHandler(psa_PrePRoleUpdate);
psa.PRoleUpdate += new PSPRoleEventHandler(psa_PRoleUpdate);
}
private void psa_PrePRoleUpdate(PRole pRole, PSEventArgs e)
{
//前置事件
}
private void psa_PRoleUpdate(PRole pRole, PSEventArgs e)
{
//后置事件
}
}
在模块里可以注册一些相关的事件，并且实现这些事件，以把一些前置或后置处理外置到主业务体外。
对于PSEvents是些方法调用的封装：
public class PSEvents
{
PRoles#region PRoles
public static void BeforePRole(PRole pRole, ObjectState state)
{
PSApplication.Instance().ExecutePrePRoleUpdate(pRole, state);
}
public static void AfterPRole(PRole pRole, ObjectState state)
{
PSApplication.Instance().ExecutePRoleUpdate(pRole, state);
}
#endregion
}
