Finding which JAR contains a class

I often want to search through a large number of JAR files looking for a particular class, and every time I do this I wish I had some utility to make it easier.  So I finally made one:

#!/bin/sh

TARGET="$1"

for i in `find . -name "*jar"`
do
  jar tvf $i | grep $TARGET > /dev/null
  if [ $? == 0 ]
  then
    echo "$TARGET is in $i"
  fi
done

Update: My colleague Chris Johnson just posted a better version of this, with some caching over at the Fusion Security Blog.