計算機外文翻譯--java抽象窗口工具包

1、外文原文The Java Abstract Windowing ToolkitFor the past five days you’ve concentrated on creating applets that do very simple things: display text, play an animation or a sound, or enable very basic interactions with the use

2、r. Once you get past that point, however, you may want to start creating more complex applets that behave like real applications, embedded in a Web page—applets that start to look like real GUI applications with buttons,

3、 menus, text fields and other elements of a real application.It’s this sort of real work in Java applets and applications that Java’s Abstract Windowing Toolkit, or AWT, was designed for. You’ve actually been using the A

4、WT all along, as you might have guessed from the classes you’ve been importing. The Applet class and most of the classes you’ve been using this week are all integral parts of the AWT. In fact, the HotJava browser is also

5、 written in Java and uses the AWT as well.The AWT provides the following:口 A full set of UI widgets and other components, including windows, menus, buttons, checkboxes, text fields, scrollbars, and scrolling lists口 Suppo

6、rt for UI “containers,” which can contain other embedded containers or UI widgets口 An event system for managing system and user events between and among parts of the AWT口 Mechanisms for laying out components in a way tha

7、t enables platform-independent UI designToday, you’ll learn about how to use all these things in your Java applets. Tomorrow, you’ll learn about creating windows, menus, and dialogs, which enable you to pop up separate w

8、indows from the browser window. In addition, you can use the AWT in stand-alone applications, so everything you’ve learned so far this week can still be used. If you find the framework of the Web browser too limiting, yo

9、u can take your AWT background and start writing full-fledged Java applications.Today, however, you’ll continue focusing on applets.Note: This is by far the most complex lesson so far. There’s a lot to cover and a lotof

10、code to go through today, so if it starts becoming overwhelming, you mightwant to take two days (or more) for this one.An AWT OverviewThe basic idea behind the AWT is that a Java window is a set of nested components, sta

11、rting from the outermost window all the way down to the smallest UI component. Components can class hierarchy that makes up the main classes in the AWT. The root of most of the AWT components is the class Component, whic

12、h provides basic display and event handling features. The classes Container, Canvas, TextComponent, and many of the other UI components inherit from Component. Inheriting from the Container class are objects that can con

13、tain other AWT components—the Panel and Window classes, in particular. Note that the java.applet.Applet class, even though it lives in its own package, inherits from Panel, so your applets are an integral part of the hie

14、rarchy of components in the AWT system.Figure 13.2.A partial AWT class hierarchy.A graphical user interface-based application that you write by using the AWT can be as complex as you like, with dozens of nested container

15、s and components inside each other. AWT was designed so that each component can play its part in the overall AWT system without needing to duplicate or keep track of the behavior of other parts in the system.The Basic Us

16、er Interface ComponentsThe simplest form of AWT component is the basic UI component. You can create and add these to your applet without needing to know anything about creating containers or panels—your applet, even befo

17、re you start painting and drawing and handling events, is already an AWT container.Because an applet is a container, you can put other AWT components—such as UIcomponents or other containers—into it.In this section, you’

18、ll learn about the basic UI components: labels, buttons, checkboxes, choice menus, and text fields. In each case, the procedure for creating the component is the same—you first create the component, and then add it to th

19、e panel that holds it, at which point it is displayed on the screen. To add a component to a panel (such as your applet, for example), use the add() method:public void init() {Button b = new Button(“OK”);add(b);}Componen