外文翻譯---aspnet介紹以及內(nèi)聯(lián)代碼和共享-jsp程序-文庫吧
2025-04-17 11:16 本頁面
【正文】 stom manipulate the text output returned from an page, they do not provide a clean HTML programming model. As the sample above illustrates, developers using only % % code blocks must custom manage page state between round trips and custom interpret posted values. In addition to code and markup, pages can contain server controls, which are programmable serverside objects that typically represent a UI element in the page, such as a textbox or image. Server controls participate in the execution of the page and produce their own markup rendering to the client. The principle advantage of server controls is that they enable developers to get plex rendering and behaviors from simple buildingblock ponents, dramatically reducing the amount of code it takes to produce a dynamic Web page. Another advantage of server controls is that it is easy to customize their rendering or behavior. Server controls expose properties that can be set either declaratively (on the tag) or programmatically (in code). Server controls (and the page itself) also expose events that developers can handle to perform specific actions during the page execution or in response to a clientside action that posts the page back to the server (a postback). Server controls also simplify the problem of retaining state across roundtrips to the server, automatically retaining their values across successive postbacks. Server controls are declared within an .htm file using custom tags or intrinsic HTML tags that contain a runat=server attribute value. Intrinsic HTML tags are handled by one of the controls in the namespace. Any tag that doesn39。t explicitly map to one of the controls is assigned the type of . Important: Note that these server controls automatically maintain any cliententered values between round trips to the server. This control state is not stored on the server (it is instead stored within an input type=hidden form field that is roundtripped between requests). Note also that no clientside script is required. In addition to supporting standard HTML input controls, enables developers to utilize richer custom controls on their pages. For example, the following sample demonstrates how the asp:adrotator control can be used to dynamically display rotating ads on a page. Each server control is capable of exposing an object model containing properties, methods, and events. developers can use this object model to cleanly modify and interact with the page. Note, however, how much cleaner and easier the code is in this new servercontrolbased version. As we will see later in the tutorial, the page Framework also exposes a variety of pagelevel events that you can handle to write code to execute a specific time during the processing of the page. Examples of these events are Page_Load and Page_Render. The example below demonstrates a simple page with three server controls, a TextBox, Button, and a Label. Initially these controls just render their HTML form equivalents. However, when a value is typed in the TextBox and the Button is clicked on the client, the page posts back to the server and the page handles this click event in the code of the page, d
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