A JSP declaration, scriptlet, or expression whose syntax is defined by the JSP specification and whose content is written according to the scripting language used in the JSP page. The JSP specification describes the syntax and semantics for the case where the language page attribute is “java”.
In advanced Java, particularly when working with JavaServer Pages (JSP), a scripting element refers to the components of JSP that allow you to embed Java code directly within the HTML or XML content of a JSP page. There are three types of JSP scripting elements:
- Declarations (
<%! %>)- Used for variable and method declarations.
- Declarations are placed outside the service method but within the body of the JSP page.
- The code inside declarations is typically used to declare variables and methods that can be used later in the JSP page.
Example:
jsp<%!
int count = 0;
count++;
}
%> - Scriptlets (
<% %>)- Used for embedding Java code within the HTML or XML content.
- Scriptlets are placed within the body of HTML or XML tags and are executed each time the page is requested.
- The code inside scriptlets is responsible for generating dynamic content.
Example:
jsp<%
String message = "Hello, World!";
out.println(message);
%>
- Expressions (
<%= %>)- Used for embedding Java expressions within the HTML or XML content.
- Expressions are evaluated, converted to a string, and inserted in the place where the expression appears in the JSP page.
Example:
jsp<p>The current count is <%= count %></p>
It’s important to note that while these scripting elements provide a way to embed Java code in JSP, it’s generally recommended to use JSTL (JavaServer Pages Standard Tag Library) and custom tags for better separation of concerns and maintainability in modern JSP development.