HttpResponse.AddOnSendingHeaders(Action<HttpContext>) HttpResponse.AddOnSendingHeaders(Action<HttpContext>) HttpResponse.AddOnSendingHeaders(Action<HttpContext>) HttpResponse.AddOnSendingHeaders(Action<HttpContext>) Method

定义

注册一个回调,在即将为此请求发送响应标头之前,ASP.NET 运行时将会调用此回调。Registers a callback that the ASP.NET runtime will invoke immediately before response headers are sent for this request.

public:
 System::Web::ISubscriptionToken ^ AddOnSendingHeaders(Action<System::Web::HttpContext ^> ^ callback);
public System.Web.ISubscriptionToken AddOnSendingHeaders (Action<System.Web.HttpContext> callback);
member this.AddOnSendingHeaders : Action<System.Web.HttpContext> -> System.Web.ISubscriptionToken
Public Function AddOnSendingHeaders (callback As Action(Of HttpContext)) As ISubscriptionToken

参数

callback
Action<HttpContext>

回调方法。The callback method.

返回

表示对 OnSendingHeaders 伪事件的订阅的 ISubscriptionToken 对象。An ISubscriptionToken object that represents the subscription to the OnSendingHeaders pseudo-event.

注解

重要

如果本机模块首先刷新响应,则不会调用 AddOnSendingHeaders 方法。The AddOnSendingHeaders method is not invoked if the native module flushes the response first.

伪事件对 onsendingheaders 与 IHttpModule 管道事件的不同之处在于,它是一个每个请求订阅,而不是按应用程序订阅。The pseudo-event OnSendingHeaders differs from the IHttpModule-level pipeline event in that it is a per-request subscription rather than a per-application subscription. 目的是回调可以修改响应状态代码,也可以设置响应 cookie 或标头。The intent is that the callback may modify the response status code or may set a response cookie or header. 其他使用注意事项和注意事项:Other usage notes and caveats:

  • 此方法仅在以下情况下有效: IIS 在集成管道模式管道中运行,并且仅在当前请求尚未发送响应标头时有效。This method is effective only when IIS runs in integrated pipeline mode pipeline and only if response headers haven't yet been sent for the current request.

  • ASP.NET 运行时不保证调用回调的线程的任何内容。The ASP.NET runtime does not guarantee anything about the thread that the callback is invoked on. 例如,如果正在执行后台刷新,则可在后台线程中同步调用回调。For example, the callback may be invoked synchronously in a background thread if a background flush is being performed. Current不保证在此类线程中可用。Current is not guaranteed to be available in such a thread.

  • 回调不得调用任何操作响应实体正文或导致刷新的方法。The callback must not call any method that manipulates the response entity body or that results in a flush. 例如,回调不得调用Redirect,因为该方法可以操作响应实体正文。For example, the callback must not call Redirect, as that method may manipulate the response entity body.

  • 回调必须只包含短时间运行的同步代码。The callback must contain only short-running synchronous code. 尝试调用异步操作或等待这样的操作可能会导致死锁。Attempting to invoke an asynchronous operation or wait on such an operation could result in a deadlock.

  • 回调不得引发异常;否则,行为是不确定的。The callback must not throw an exception; otherwise behavior is undefined.

适用于