外文翻譯----struts開發(fā)的最佳實(shí)踐-wenkub
2023-05-19 11:47:30 本頁面
【正文】 nt code in every Action class of your Web application. Second, it gives the application more control over generic tasks by centralizing the behavior in one Action class. Best Practice 3. Use ActionForm to work on session data In a Strutsbased Web application, each ActionForm extends . These ActionForms encapsulate page data and provide a validation framework to validate request parameters. Most Web applications maintain data in session to make them available throughout the application. This best practice addresses this Web application feature. It allows methods toSession() and fromSession() to move session data to and from the form data. Thus, it addresses session data maintenance in a Web application. To adhere to this practice, follow these steps: 1. Create an abstract class named BP3Form by extending . 2. In BP3Form, add methods with access modifiers as in public abstract void toSession(SessionData sessionData) and void fromSession(SessionData sessionData). 3. In every ActionForm, extend BP3Form and implement the abstract methods in which the form data is transported to and from the session. 4. The corresponding Action class may determine the order in which these methods are called. For example, you could invoke method toSession() on the ActionForm just before actionForward is determined. When to use this practice This practice is most useful when session data is maintained as a single object and/or every page manipulates or uses session data. Best Practice 4. Handle exceptions effectively Conventionally, when an application exception occurs in an Action class, the exception is first logged. Then the class creates anActionError and stores it in the appropriate scope. This Action class then forwards control to the appropriate ActionForward. Listing 3 shows how Action class handles exceptions. Listing 3. Exception handling in an Action class try { //Code in Action class } catch (ApplicationException e) { //log exception ActionErrors actionErrors = new ActionErrors()。 it allows you to separate presentation from other application tiers. The libraries are easy to use and you can read them in XMLlike fashion. You can easily maintain the JSP ponents by minimizing the use of Java scriptlets in them. The JSP tags that Struts provides include HTML, logic, and bean tags. ActionErrors You use ActionErrors to support exception handling. An ActionError traps and propagates an application exception to the View layer. Each one is a collection of ActionError instances. ActionErrors encapsulate error messages, while the /html:errors in the Presentation layer renders all error messages in the ActionError collection. Best Practice 1. Reuse data across multiple ActionForms Now that you are familiar with the Struts ponents, we will continue by showing you ways to get the most out of the framework. First, Struts remends that you associate every JSP object with an ActionForm, which encapsulates data represented in the screen. You access the form data in the JSP object using accessory methods found in ActionForm. Listing 1 shows the conventional use of ActionForm tag in the View layer. Listing 1. Using Action
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