Caching contents of a page?

Question

Hi,

I'm generating page content like:

// index.jsp
<%
    List<Horse> horses = database.getHorses();
    for (Horse it : horses) {
        %>
        <div><%= it.getName() %></div>
       <%
    }
%>

is it possible to grab the entire page content at the end of the jsp file, and dump it into a String, like:

String page = this.getPrintWriter().toString();

I'm just curious if this is possible. I might try caching the page as a String, but would need to rewrite my page generation to build everything in one StringBuilder like:

StringBuilder sb = new StringBuilder();
sb.append("<div>"); sb.append(it.getName()); sb.append("</div>");
...
<%= sb.toString() %>
String cached = sb.toString();

Thanks

Answer 1

Since it's user-specific data, you can't use GAE's memcache for this. It's an application wide cache. I'd just store it in the session scope.

HttpSession session = request.getSession();
List<Horse> horses = (List<Horse>) session.getAttribute("horses");
if (horses == null) {
    horses = database.getHorses();
    session.setAttribute("horses", horses);
}

That said, try to avoid using scriptlets as much as possible. The above can perfectly be done in a Servlet class and you can display them using JSTL c:forEach as follows:

<c:forEach items="${horses}" var="horse">
    <div>${horse.name}</div>
</c:forEach>

Capturing generated page content can't be done by simply calling PrintWriter#toString(). The StringBuilder idea is funny, but it's really not worth it. Caching dynamic content has very little benefits for the purposes as you mention.

Best what you in this case can do with regard to page caching is just to leverage the webbrowser's default task to cache GET requests.

See also

• How to avoid Java code in JSP?
• How to capture dynamically generated content?