Wednesday, September 26, 2007

Reload webapp from ant script

A co-worker asked me how he can reload a web-application from an ant script. GDS was very helpfull finding the line in an old ant script I used to use. In the example below you might want to define $project.output

<property name="project.output" value="WEB-INF/classes"/>
<!-- reload the current webapp to refresh the classes that we just changed -->
<concat><fileset dir="${project.output}/log" includes="reload.log"/></concat>

Monday, September 24, 2007

RequestDispatcher.forward() and filters

If you have read this post then you probably know that if you use RequestDispatcher.forward() (or RequestDispatcher.include()) the filter chain does not get re-called for the forwarded servlet/jsp. However, if you read more closely you see that Craig was talking about the 2.3 servlet spec. Since we are using tomcat 5.5 which conforms to the 2.4 spec, you should know that there's a new <dispatcher> element in the deployment descriptor with possible values REQUEST, FORWARD, INCLUDE, and ERROR. You can add any number of entries to a <filter-mapping> tag and individually decide which filter gets called when. An Example:



Simpler GUI for Jad, The Java Decompiler from As I Learn

This is definitely the most useful two-liner I've seen in a while:
Simpler GUI for Jad, The Java Decompiler.

I naturally customized it to:

jad -o -s java -lnc -d%TEMP% %1
"C:\Program Files\TextPad 5\TextPad.exe" %TEMP%.\

Changed extension to java so that textpad does syntax highlighting; added -lnc so that jad outputs the original line numbers as comments and I can trace the exceptions I get

(after a few questions from people i'm editing this post:)
You will need to download jad and extract the exeutable to somewhere on your path, say C:\windows (or c:\winnt). Then create a new .cmd file, paste the above into the .cmd file, and put it somewhere. Then rightclick any .class file you can find, choose "Open With..."->"Choose Program"->"Browse..." and find the cmd file you created (don't forget to check the "Always use this program"). This way, any .class you'll double-click will decompile and open in textpad.

Monday, September 17, 2007

Using java regular expressions to match groups

It's been demonstrated over and over again, but I always seem to forget the "simple example". So here it is:

import java.util.regex.Matcher;
import java.util.regex.Pattern;
*Going to match a URL that looks like this
* /url/prefix/--sitename--/menu.--menuid--/?param=--itemid--
* and change it into
* /url/prefix/--sitename--/--menuname--/--itemname--
String expr="(/url/prefix/[a-zA-Z0-9_-]+)/menu\\.([a-zA-Z0-9_-]+)/\\?param=([a-zA-Z0-9_-]+)";
Pattern p = Pattern.compile(expr);
Matcher m = p.matcher(uri);
if ( m.matches() ) {
menuitem =;
guid =;
if ( guid != null && prefix != null && menuitem != null ) {

Thursday, September 6, 2007

Does GDS slows my hard disk?

I've a encountred a strange problems that when Google Desktop Search is running on my PC (which it almost always is), my hard disk's read speed is about 1/6th of the normal speed. I'll contact google to see if this is a known issue. I'm using several HD benchmark tools to test the speed, most notably Simpli Software's Hd Tach.

Here are screenshots of my disk's speed with and without GDS running.

Avoding browser history when changing iframe src

We ran into a problem where we needed to have an iframe who's source needed to be changed dynamically by a javascript based on some user data. The issue was that Internet Explorer saved the iframe's old url in the history. The simple solution is to dynamically write the iframe with it's real src instead of having an iframe on the page and then changing it's src.

You do it like this:

var iframeHeaderCell = document.getElementById('wheretoputheiframe');
var dynamicURL = 'http://...' //your url
var iframeHeader = document.createElement('IFRAME'); = 'iframeHeader';
iframeHeader.src = dynamicURL ;
iframeHeader.width = ...;
iframeHeader.height = ...;
iframeHeader.scrolling = 'no';
iframeHeader.frameBorder = 0;
iframeHeader.align = 'center';
iframeHeader.marginwidth = 0;
iframeHeader.marginheight = 0;
iframeHeader.hspace = 0;
iframeHeader.vspace = 0;

Elementry, my dear Watson.