JSP Tags

JavaServer Pages (JSP) allows you to embed Java code directly within HTML, making it a powerful tool for dynamic web content generation. JSP tags are essential components in this process.

Directives

JSP Directives provide global information about the JSP page and its settings. They are used to control aspects like the page language, content type, or buffer size.

• Syntax: <%@ directive attribute="value" %>
• Example:
  
  1	<%@ page language="java" contentType="text/html; charset=ISO-8859-1" %>

• Common Directives
  • page: Specifies page-level settings like language and buffer size.
  • include: Includes another file during compilation.
  • taglib: Declares a tag library for use in the JSP page.

Scriptlets

Scriptlets allow you to embed Java code within the HTML body of a JSP page. They are executed every time the page is requested.

• Syntax: <% // Java code here %>
• Example:
  
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  <%     String name = "John Doe";     out.println("Hello, " + name); %>

• Use: While scriptlets are still used, it’s best to avoid them in favor of more modern approaches like EL (Expression Language) and JSTL (JSP Standard Tag Library).

Expressions

JSP Expressions are used to insert values directly into the output. They evaluate an expression and automatically convert the result into a string, which is then sent to the client.

• Syntax: <%= expression %>
• Example:
  
  1	<%= new java.util.Date() %>

• Use: Expressions simplify output generation, making the code more concise compared to scriptlets.

Declarations

Declarations allow you to declare variables and methods that are visible throughout the entire JSP page. They are typically used to define reusable methods or variables that need to be accessed globally within the page.

• Syntax: <%! declaration %>
• Example:
  
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  <%!     public String getWelcomeMessage() {         return "Welcome to JSP!";     } %>