Declaring a Bean in a JSP Page
Example 6-1 shows a JSP page that uses the bean described in Table 6-1 to display a cartoon strip.
<html>
<head>
<title>A dose of Dilbert</title>
</head>
<body bgcolor="white">
<h1>A dose of Dilbert</h1>
<jsp:useBean id="cartoon"
class="com.ora.jsp.beans.motd.CartoonBean" />
<img src="images/<jsp:getProperty name="cartoon"
property="fileName" />">
</body>
</html>
Before you use a bean in a page, you must tell the JSP container the
type of bean it is and associate it with a name; in other words, you
must declare the bean. The first JSP action in Example 6-1, <jsp:useBean>
, is
used for this purpose:
<jsp:useBean id="cartoon" class="com.ora.jsp.beans.motd.CartoonBean" />
The <jsp:useBean>
action is one of the JSP
standard actions (identified by the jsp
prefix).
The action creates an instance of the bean class specified by the
class
attribute and associates it with the name
specified by the id
attribute. The name must be
unique in the page and be a valid Java variable name; it must start
with a letter and can’t contain special characters
such as dots, plus signs, etc.
Other attributes you can specify for the
<jsp:useBean>
action are
scope
, type
, and
beanName
. Chapter 10 explores
how the scope
attribute is used. The others are
rarely used, but Appendix Acontains descriptions of how you can use
them if you wish.
Get JavaServer Pages, 3rd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.