JavaServer Pages (JSP) is a server-side technology used to create dynamic web pages using Java. A JSP page is a combination of static content and JSP elements that generate dynamic output. It processes user requests and sends the response back to the browser.
- It is converted into a Servlet internally before execution.
- JSP elements help control logic, flow, and data handling.
Types of JSP Elements
JSP elements are used to add dynamic behavior and control the execution of the page.
Directive Elements
Used to provide instructions to the JSP container during the translation phase (before execution).
- Do not produce output directly
- Affect overall structure and behavior of JSP page
- Applied before JSP is converted into Servlet
Types of Directives
1. Page Directive
- Defines page-level settings
- Controls session usage, error handling, buffering
Syntax:
<%@ page attribute="value" %>
2. Include Directive
- Includes file at translation time
- Static inclusion (merged before execution)
Syntax:
<%@ include file="header.jsp" %>
3. Taglib Directive
- Declares custom tag libraries
- Used in JSTL and frameworks
Syntax:
<%@ taglib uri="uri" prefix="prefix" %>
2. Action Tags
Used to perform runtime operations and interact with other resources.
- Executed at request time
- Can generate dynamic content
Types of Action tag
<jsp:forward>: Forwards the request and response to another resource (JSP/Servlet)<jsp:include>: Includes another resource dynamically at runtime<jsp:useBean>: Creates or locates a JavaBean object<jsp:setProperty>: Sets the value of a property in a JavaBean<jsp:getProperty>: Retrieves and displays the value of a bean property<jsp:param>: Passes parameters to another resource (used with forward/include)<jsp:plugin>: Embeds external components like applets<jsp:fallback>: Displays a message if the plugin fails to run
3. Scripting Elements
Used to write Java code inside JSP.
- Allows embedding Java logic directly
- Executed inside generated Servlet
Types of Scripting elements
1. Scriptlet Tag
- Contains Java statements
- Executes inside
_jspService()
Syntax:
<%
int a = 10;
%>
2. Expression Tag
- Prints value directly
- Automatically converts to out.print()
Syntax:
<%= a %>
3. Declaration Tag
- Declares variables/methods
- Placed outside _jspService()
Syntax:
<%! int a = 10; %>
4. Expression Language (EL)
Simplifies accessing data from objects.
- No need to write Java code
- It Improves readability
Syntax:
${user.name}
Advantages of JSP Page Elements
- Makes code easy to understand and manage
- Helps in creating dynamic web pages
- Reduces use of complex Java code
- Supports code reusability