BBS水木清华站∶精华区

发信人: afei (飞色精灵), 信区: Java
标  题: Java Beans Concepts
发信站: BBS 水木清华站 (Tue Dec 16 16:18:22 1997)

JavaBeans Concepts

     The JavaBeans API makes it possible to write component software in Java.
     Components are self-contained, reusable software units that can be visually composed
     into applets or applications using visual application builder tools.

     JavaBeans is a core JDK1.1 capability: Any JDK1.1-compliant browser or tool
     implicitly supports JavaBeans.

     JavaBean components are called Beans. A "Beans aware" builder tool maintains Beans
     in a palette or toolbox. You can select a particular Bean from the toolbox, drop it into
     a form, modify it's appearance and behavior, define its interaction with other Beans,
     and compose it and other Beans into an applet, application, or new Bean. All this can
     be done without writing a line of code.

     The following list briefly describes key Bean concepts:

         Builder tools discover a Bean's properties, methods, and events by introspection.
         Beans support introspection in two ways:
              By adhering to specific naming conventions, known as design patterns,
              when naming Bean features. Bean introspection relies on the core
              reflection API to discover Bean features via design patterns.
              By explicity providing property, method, and event information with a
              related Bean Information class. A Bean information class implements the
              BeanInfo interface.
         See Chapter 8 of the JavaBeans API Specification for an introspection, design
         pattern, and BeanInfo discussion.
         Properties are a Bean's appearance and behavior attributes that can be changed at
         design time. Properties are exposed to builder tools by design patterns or a
         BeanInfo class. See Chapter 7 of the JavaBeans API Specification for a
         complete property discussion.
         Beans expose properties so that they can be customized at design time.
         Customization is supported in two ways: By using property editors, or by using
         more sophisticated Bean customizers. See Chapter 9 of the JavaBeans API
         Specification for a customization discussion.
         Beans use events to communicate with other Beans. A Bean that wants to receive
         events (a listener Bean) registers its interest with the Bean that fires the event (a
         source Bean). Builder tools can examine a Bean and determine which events that
         Bean can fire (send) and which it can handle (receive). See Chapter 6 of the
         JavaBeans API Specification for a complete event discussion.
         Persistence enables Beans to save their state, and restore that state later.
         JavaBeans uses Java Object Serialization to support persistence. See Chapter 5 of
         the JavaBeans API Specification for a complete persistence discussion.
         A Bean's methods are no different than Java methods, and can be called from
         other Beans or a scripting environment. By default a all public methods are
         exported.

     Beans can be used with both builder tools, or manually manipulated by text tools
     through programmatic interfaces. All key APIs, including support for events,
     properties, and persistence, have been designed to be easily read and understood by
     human programmers as well as by builder tools.

--
※ 来源:·BBS 水木清华站 bbs.net.tsinghua.edu.cn·[FROM: curie.eps.jhu.e]