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JavaBeans Component Design Conventions
JavaBeans component design conventions govern the properties of the class and govern the public methods that give access to the properties.
A JavaBeans component property can be
- Read/write, read-only, or write-only
- Simple, which means it contains a single value, or indexed, which means it represents an array of values
There is no requirement that a property be implemented by an instance variable; the property must simply be accessible using public methods that conform to certain conventions:
- For each readable property, the bean must have a method of the form
PropertyClass getProperty() { ... }
- For each writable property, the bean must have a method of the form
setProperty(PropertyClass pc) { ... }
In addition to the property methods, a JavaBeans component must define a constructor that takes no parameters.
The Duke's Bookstore application JSP pages
enter.jsp
,bookdetails.jsp
,catalog.jsp
, andshowcart.jsp
use thedatabase.BookDB
anddatabase.BookDetails
JavaBeans components.BookDB
provides a JavaBeans component front end to the access objectBookDBAO
. Both beans are used extensively by bean-oriented custom tags (see Custom Tags in JSP Pages). The JSP pagesshowcart.jsp
andcashier.jsp
usecart.ShoppingCart
to represent a user's shopping cart.The JSP pages
catalog.jsp
,showcart.jsp
, andcashier.jsp
use theutil.Currency
JavaBeans component to format currency in a locale-sensitive manner. The bean has two writable properties,locale
andamount
, and one readable property,format
. Theformat
property does not correspond to any instance variable, but returns a function of thelocale
andamount
properties.public class Currency { private Locale locale; private double amount; public Currency() { locale = null; amount = 0.0; } public void setLocale(Locale l) { locale = l; } public void setAmount(double a) { amount = a; } public String getFormat() { NumberFormat nf = NumberFormat.getCurrencyInstance(locale); return nf.format(amount); } }
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This tutorial contains information on the 1.0 version of the Java Web Services Developer Pack.
All of the material in The Java Web Services Tutorial is copyright-protected and may not be published in other works without express written permission from Sun Microsystems.