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Creating and Using a JavaBeans Component

You declare that your JSP page will use a JavaBeans component using either one of the following formats:

<jsp:useBean id="beanName"	
   class="fully_qualified_classname" scope="scope"/>
 

or

<jsp:useBean id="beanName"	
   class="fully_qualified_classname" scope="scope">	
   <jsp:setProperty .../>	
</jsp:useBean>
 

The second format is used when you want to include jsp:setProperty statements, described in the next section, for initializing bean properties.

The jsp:useBean element declares that the page will use a bean that is stored within and accessible from the specified scope, which can be application, session, request, or page. If no such bean exists, the statement creates the bean and stores it as an attribute of the scope object (see Using Scope Objects). The value of the id attribute determines the name of the bean in the scope and the identifier used to reference the bean in other JSP elements and scriptlets.


Note: In the section JSP Scripting Elements we mentioned that you must import any classes and packages used by a JSP page. This rule is slightly altered if the class is only referenced by useBean elements. In these cases, you must only import the class if the class is in the unnamed package. For example, in What Is a JSP Page?, the page index.jsp imports the MyLocales class. However, in the Duke's Bookstore example, all classes are contained in packages and thus are not explicitly imported.

The following element creates an instance of Currency if none exists, stores it as an attribute of the session object, and makes the bean available throughout the session by the identifier currency:

<jsp:useBean id="currency" class="util.Currency"	
   scope="session"/>
 
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