Question

Is it possible to use JSP sort of as a template without having code inside?

Values should be inserted into a hash map, and the JSP can read the values from there.

Is it possible to code like this in a GAE application, or do you need external tools/frameworks to accomplish this?

In other words, is it possible to pass values from the servlet handler to the JSP template?

Answer 1

Next to JSP there’s also the Servlet API.

If the map is request or session specific, then create a class which extends HttpServlet and implement doGet() method like follows:

Map<K, V> map = createItSomehow();
request.setAttribute("map", map);
request.getRequestDispatcher("/WEB-INF/page.jsp").forward(request, response);

Register the Servlet in web.xml on a certain url-pattern and invoke an URL matching this pattern.

This way the map is available as ${map} in JSP. Here’s an example which iterates over the map using JSTL c:forEach tag:

<c:forEach items="${map}" var="entry">
    Key: ${entry.key}, Value: ${entry.value}<br>
</c:forEach>

If the map is an application wide constant, then rather implement ServletContextListener and do the following in contextInitialized() method:

Map<K, V> map = createItSomehow();
event.getServletContext().setAttribute("map", map);

Register the ServletContextListener in web.xml as follows:

<listener>
    <listener-class>com.example.Config</listener-class>
</listener>

and it will be executed on webapp’s startup. The map is then available in JSP by ${map} as well.

See also:

• How to avoid Java code in JSP
• Hidden features of JSP/Servlet
• Coreservlets.com JSP/Servlet tutorials