Blarg #13: I think it is silly that your HelloWorld servlet produces static content

Why is it that the first servlet people teach is one that produces static content? HelloWorld.html is appropriate. HelloWorld.java is silly. The more JSP/Servlets I do, the more frustrated I get when I see others do a mediocre job of introducing the important concepts. Sure it is important to teach that code goes in WEB-INF/classes and all the other beginner's stuff, but it certainly doesn't merit a static servlet.

How about we all figure out an appropriate dynamic, simple servlet for the every present I'm-coding-my-first-servlet exercise. The only thing I can think of at the moment is a Servlet that displays the date, and that is far to cheesy to end the blog with. I'll finish writing this when I come up with a slightly better idea.

How about a simple hit counting filter? e.g. "HelloWorld! You've been here X times?", replacing the x with an appropriate increment. Here is the code.

package example;

import java.io.*;
import javax.servlet.http.*;
import javax.servlet.*;

public class HelloServlet extends HttpServlet {
  int count = 0;
  public void doGet (HttpServletRequest req,
                     HttpServletResponse res)
    throws ServletException, IOException {
    // increment x
    count ++;

    // write out some text
    PrintWriter out = res.getWriter();

    out.println("Hello, world! This page has been visited "+count+" times.");
    out.close();
  }
}

Can you think of a better example? I'll be teaching this for real. Perhaps to your next employee. You don't want your next coder making static servlets do you?

Jayson Falkner
jayson@jspinsider.com