Page.IsCallback

最新推荐文章于 2021-03-28 17:02:59 发布

最新推荐文章于 2021-03-28 17:02:59 发布 · 112 阅读

本文探讨了 ASP.NET 2.0 中引入的新特性 Client Callback 的工作原理及其实现方式。该特性允许在不触发页面回发的情况下异步调用服务器端事件，从而提高用户体验并减少服务器负载。通过使用 Page 类中的 GetCallbackEventReference 方法可以生成客户端所需的异步调用代码。

IsPostback shows the page is posted back or loaded first time.
IsCallBack indicates whether the page request is the result of a call back.

Client Callback is a new feature in ASP.NET 2.0. It allows calling server side events asynchronously, without causing postback. It is possible to do asynchronous call using explicit AJAX, but in ASP.NET 2.0 and above versions a clean framework is available to do this. This article describes how Client Callbacks works and also explores how Client Callback framework has been implemented in ASP.NET.

Consider in a page you have a textbox and a button. when the button is clicked,you need to display some complex content in the textbox(suppose that it takes 5 seconds).there are two ways to do this,By explicit Ajax,or Client Callback.the following is the second method.

Generating Client Side Code for Callback

For implementing callback in client side, a new method "GetCallbackEventReference" in Page Class is available. You can use this method to generate client side code which is required for the asynchronous call to server. In the example, client side code is generated like this;