AJAX, Unicode and Java

As you might already noticed I'm actually busy in using JavaScript. That's mainly because I develop an AJAX application based on J2EE. To simplify my work with JavaScript I use the library mootools which is a great facilitation over plain JavaScript, especially if you'd like to to your stuff object oriented.

By using the library I came around a strange problem with unicode handling. My application was written completely in UTF-8 but as soon as I sent data over AJAX to the server it didn't get handled correctly.

After some search I came across the solution: simply add the following line of to the top of your Servlet to let it know the POST data is UTF-8 encoded.

public class ChatServlet extends javax.servlet.http.HttpServlet implements
  javax.servlet.Servlet {

protected void doPost(HttpServletRequest request,
    HttpServletResponse response) throws ServletException, IOException {
  request.setCharacterEncoding("UTF-8");
}
}

Log to Firefox console

You can log to the Firefox console by using the method "dump" in javascript. To enable this feature in Firefox type in about:config in the address bar and create there a new boolean entry with the name "browser.dom.window.dump.enabled" and the value "true".

Now start Firefox from the command line by entering "firefox -console". All messages passed to dump() will be printed on the command line.

To automatically add a timestamp to your messages and avoid error messages in other browsers I've created this little function:

function log(message) {
  if(window.dump) {
    var date = new Date();
    var hours = date.getHours();
    if(hours < 10) hours = "0" + hours;
    var minutes = date.getMinutes();
    if(minutes < 10) minutes = "0" + minutes;
    var seconds = date.getSeconds();
    if(seconds < 10) seconds = "0" + seconds;
    dump(hours + ":" + minutes + ":" + seconds + " - someapp: " + message + "\n");
  }
}