Howto decompile a complete jar-file
Download JAD and jadAlign. Unpack the zips and copy the two executables in a path-directory. Put this little shell-script in your path.
decompile_jar.sh
OLD_PWD=$PWD
mkdir src 2>/dev/null
cp $1 src/$1.zip
cd src/
unzip $1.zip
rm -f $1.zip
find . -name "*.class" -exec jad -r -s "jad" -lnc {} \;
find . -name "*.class" -exec rm -f {} \;
find . -name "*.jad" -exec jadAlign {} `basename {} .jad`.java \;
find . -name "*.jad" -exec rm -f {} \;
cd $OLD_PWD
Open a shell (under windows you can use cygwin), change to the directory where the jar-file can be found and call
decompile_jar.sh jar2decompile.jar
At the end you should have a new directory src with the decompiled and re-aligned java-sources.
Try it 
Very nice and interesting! Thanks.
Some hints and questions about the shell script.
Why you need the “OLD_PWD” stuff? You can simple
mkdir src
cd src
.. do anything
cd ..
The find command should also called with
find -type f
to aviod executing jad and the other tools to run on a directory.
The mkdir can be used better with
mkdir src > /dev/null 2>&1
to also grab the stdout