JSP Declarations
JSP Declarations
TABLE 91
Scripting Settings
JSP Configuration
Scripting Encountered
Unspecified
Valid
false
Valid
true
Translation Error
JSP Declarations
A JSP declaration is used to declare variables and methods in a page's scripting language. The
syntax for a declaration is as follows:
<%!
scripting-language-declaration %>
When the scripting language is the Java programming language, variables and methods in JSP
declarations become declarations in the JSP page's servlet class.
Initializing and Finalizing a JSP Page
You can customize the initialization process to allow the JSP page to read persistent
configuration data, initialize resources, and perform any other one-time activities; to do so, you
override the jspInit method of the JspPage interface. You release resources using the
jspDestroy
method. The methods are defined using JSP declarations.
For example, an older version of the Duke's Bookstore application retrieved the object that
accesses the bookstore database from the context and stored a reference to the object in the
variable bookDBAO in the jspInit method. The variable definition and the initialization and
finalization methods jspInit and jspDestroy were defined in a declaration:
<%!
private BookDBAO bookDBAO;
public void jspInit() {
bookDBAO =
(BookDBAO)getServletContext().getAttribute(
"bookDB");
if (bookDBAO == null)
System.out.println(
"Couldn't get database.");
}
%>
When the JSP page was removed from service, the jspDestroy method released the BookDBAO
variable.
JSP Declarations
The Java EE 5 Tutorial · September 2007
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