This is a simple trick possible using Jython; to call jinja2 template engine under JSP we instantiate the PythonInterpreter class of Jython, set some parameters in the interpreter and then call jinja2 to render a template and write to the Java “out” object.

To install Jython, just download the last stable version Jython 2.5 and then install it as “Standalone” version; the installer will create a simple jython.jar file under the installation directory, copy this package to your Java web project under the \WEB-INF\lib or where you put your web application libraries.

Later, copy the jinja2 module to the \build\classes.

Create a simple template under the WebContent\templates\template.html with contents below:

This is just a Jinja2 template test !

Parameter "p" = {{ request.getParameter("p") }}

Getting session attribute: {{ session.getAttribute("session_attribute") }}

Iterating over Java array:

{% for user in users %}
	
{{ user }}
{% endfor %}

And now create a file called index.jsp in the root of the WebContent, with the contents:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%@page import="org.python.util.PythonInterpreter" %>







<%
	PythonInterpreter py = new PythonInterpreter();

	String[] users = {"User Number One", "User Number Two"};
	session.setAttribute("session_attribute", "Testing Session");
	
	py.set("out",     out);
	py.set("request", request);
	py.set("session", session);
	py.set("users",   users);
	py.set("context_path", application.getRealPath("/") + "templates");
		
	py.exec("from jinja2 import Environment, FileSystemLoader");
	py.exec("env = Environment(loader=FileSystemLoader(context_path))");
	py.exec("template = env.get_template('template.html')");
	py.exec("out.write(template.render(locals()))");
%>

The structure will be like this:

And the output will be something like this: