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This article mainly introduces "case analysis of the life cycle of ASP.NET server controls". In daily operations, I believe that many people have doubts about the life cycle of ASP.NET server controls. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods, hoping to help you answer the doubts of "case analysis of the life cycle of ASP.NET server controls". Next, please follow the editor to study!

This paper analyzes the life cycle of ASP.NET server control with an example. Share it with you for your reference. The details are as follows:

(1) initialization-in this phase, two main tasks are completed: first, initializing the settings required during the life cycle of the incoming Web request; and second, tracking the view state. First, the page framework raises the Init event by default and calls the OnInit () method, which the control developer can override to provide initialization logic for the control. After that, the page framework calls the TrackViewState method to track the view state. It is important to note that in most cases, the TrackViewState method implementation provided by the Control base class is sufficient. Developers may need to override TrackViewState methods only if the control defines complex properties.

(2) load View State-the main task of this phase is to check whether the server control exists and whether it needs to restore its state to the state where it ended before the request was processed. Therefore, this process occurs during the page return process, rather than initializing the request process. At this stage, the page framework automatically restores the ViewState dictionary. If the server control does not maintain its state, or if it has the ability to save all its state by default and use the ViewState dictionary, then the developer does not have to implement any logic. For those data types that cannot be stored in the ViewState dictionary or where custom state management is required, developers can override the LoadViewState method to customize state recovery and management.

(3) deal with postback data-if you want the control to check the form data sent back by the client, you must implement the LoadPostData () method of the System.Web.UI.IPostBackDataHandler interface. Therefore, only controls that handle postback data participate in this phase.

(4) loading-at this stage, the server control in the control tree has been created and initialized, the state has been restored, and the form control reflects the client's data. At this point, the developer can implement the common logic for each request by overriding the OnLoad () method.

(5) send postback change notification-at this stage, the server control uses an event as a signal to indicate a change in control state due to a postback (so this phase is used only during the postback process). To establish this signal, the developer must use the System.Web.UI.IPostBackDataHandler interface again and implement another method-RaisePostBackChangedEvent (). The judgment process is that if the state of the control changes due to a postback, LoadPostData () returns true; otherwise it returns false. The page framework tracks all controls that return true and calls RaisePostDataChangedEvent () on those controls.

(6) handle postback events-this stage deals with client events that cause postback. To facilitate mapping client-side events to server-side events for processing, developers can implement this logic at this stage by implementing the RaisePostBackEvent () method of the System.Web.UI.IPostBackEventHandler interface. In this way, the server control will successfully capture the postback client event for server-side processing.

(7) pre-rendering-this phase completes any work required before the control is generated. This is usually done by overriding the OnPreRender () method. It is important to note that at this stage, changes made to the state of the control at the pre-rendering stage can be saved, while changes made during the rendering phase are lost.

(8) Save state-if the server control does not maintain state, or if it has the ability to save all its state by default and use the ViewState dictionary, then the developer does not have to implement any logic at this stage. Because the process of saving the state is automatic. If the server control requires custom state saving, or if the control cannot store special data types in the ViewState dictionary, you need to override the SaveViewState () method to achieve state saving.

(9) rendering-represents the process of writing tagged text to the HTTP output stream. The developer overrides the Render () method to customize the markup text on the output stream.

(10) disposal-in this phase, the Dispose () method is overridden to release references to expensive resources, such as database links.

(11) Uninstall-does the same work as the "disposal" phase, but developers typically perform cleanup in the Dispose () method instead of handling the Unload event.

At this point, the study of "instance analysis of the life cycle of ASP.NET server controls" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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