<%@ page contentType="text/html; charset=UTF-8" %> <%@ page import="java.util.Date" %> <%@ page import="java.text.SimpleDateFormat" %> <%! // Declaration: Instance variable and method private int visitCount = 0; private String formatDate(Date date) { SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); return sdf.format(date); } %> Simple JSP Example - Gumdrop

Simple JSP Example

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This JSP demonstrates basic JSP functionality including:

Page directives
Import statements
Declarations (<%! %> blocks)
Scriptlets (<% %> blocks)
Expressions (<%= %> blocks)

JSP Code Examples

1. Page Directive

<%@ page contentType="text/html; charset=UTF-8" %>

<%@ page import="java.util.Date" %>

<%@ page import="java.text.SimpleDateFormat" %>

2. Declaration (Instance Variables and Methods)

<%!

    private int visitCount = 0;

    private String formatDate(Date date) {

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        return sdf.format(date);

    }

%>

3. Scriptlet (Java Code)

<%

    visitCount++;

    Date currentTime = new Date();

    String greeting;

    int hour = currentTime.getHours();

    if (hour < 12) {

        greeting = "Good morning";

    } else if (hour < 18) {

        greeting = "Good afternoon";

    } else {

        greeting = "Good evening";

    }

%>

4. Expression (Output Values)

<p><%= greeting %>! Welcome to Gumdrop JSP.</p>

<p>Current time: <%= formatDate(currentTime) %></p>

<p>This page has been visited <%= visitCount %> time(s) this session.</p>

Generated Output

<% // Scriptlet: increment visit counter and generate greeting visitCount++; Date currentTime = new Date(); String greeting; int hour = currentTime.getHours(); if (hour < 12) { greeting = "Good morning"; } else if (hour < 18) { greeting = "Good afternoon"; } else { greeting = "Good evening"; } %>

<%= greeting %>! Welcome to Gumdrop JSP.

Current time: <%= formatDate(currentTime) %>

This page has been visited <%= visitCount %> time(s) this session.

How This Works

When you request this JSP file, Gumdrop's JSP implementation:

Parses the JSP source using either the traditional JSP parser or XML JSP parser
Creates an Abstract Syntax Tree (AST) representing all JSP elements
Generates Java servlet source code from the AST
Compiles the generated servlet using the internal Java compiler
Loads and instantiates the servlet to handle your request

The generated servlet implements javax.servlet.http.HttpServlet and contains all your JSP code transformed into appropriate servlet methods.