HttpCacheValidateHandler 委托

定义

命名空间:
System.Web
程序集:
System.Web.dll

表示在从缓存提供项之前调用的方法，用于验证缓存项。

public delegate void HttpCacheValidateHandler(HttpContext ^ context, System::Object ^ data, HttpValidationStatus % validationStatus);
public delegate void HttpCacheValidateHandler(HttpContext context, object data, ref HttpValidationStatus validationStatus);
type HttpCacheValidateHandler = delegate of HttpContext * obj * HttpValidationStatus -> unit
Public Delegate Sub HttpCacheValidateHandler(context As HttpContext, data As Object, ByRef validationStatus As HttpValidationStatus)

参数

context
HttpContext

HttpContext包含有关当前请求的信息的对象。

data
Object

用于验证缓存项的用户提供的数据。

validationStatus
HttpValidationStatus

HttpValidationStatus枚举值。 委托应设置此值以指示验证结果。

示例

下面的代码示例演示如何向应用程序添加新的缓存验证委托。


private void Page_Load(Object sender, EventArgs e)
{
   Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(CacheValidate1), null);
}

public void CacheValidate1(HttpContext context, Object data, ref HttpValidationStatus status) 
{
   if (context.Request.QueryString["Valid"] == "false") 
   {
      status = HttpValidationStatus.Invalid;
   }
   else 
   {
      status = HttpValidationStatus.Valid;
   }
}


Private Sub Page_Load(sender As Object, e As EventArgs)
   Response.Cache.AddValidationCallback(New HttpCacheValidateHandler(AddressOf CacheValidate1), Nothing)
End Sub
   
Public Sub CacheValidate1(context As HttpContext, data As Object, ByRef status As HttpValidationStatus)
   If context.Request.QueryString("Valid") = "false" Then
      status = HttpValidationStatus.Invalid
   Else
      status = HttpValidationStatus.Valid
   End If
End Sub

注解

如果缓存项在方法范围内 HttpCacheValidateHandler 失效，则会从缓存中逐出该项，并且该项的请求被视为缓存未命中。

扩展方法

名称 说明
GetMethodInfo(Delegate)

获取一个对象，该对象表示由指定委托表示的方法。

适用于

另请参阅