I need to analyse which classes are used (referenced) by the different .class files in a jar. I know that
jdeps -v example.jar
produces this output. Unfortunately, I need a solution that works if the user has only a JDK 1.7. How could this be achieved?
I've been able to obtain seemingly good results with javap -c and a regex filter.
I used cygwin to obtain my results, but you should be able to do this in any environment, all you need is a tool to unzip, javap and a tool to execute regular expressions. In current Windows versions, powershell would provide those features.
The following code will list the classes referenced by each class inside a jar file :
mkdir workDir
unzip yourJar.jar -d workDir
shopt -s globstar
for classFile in **/*.class; do
echo "Classes used in $classFile :"
javap -c "$classFile" | grep -Eo "([a-zA-Z0-9]+/)+[A-Z][a-zA-Z0-9]*" | sort -u
echo
done
You said you wanted the classes referenced in a jar file, so assuming you don't want the detail of each class this should work :
mkdir workDir
unzip yourJar.jar -d workDir
shopt -s globstar
for classFile in **/*.class; do
javap -c "$classFile" | grep -Eo "([a-zA-Z0-9]+/)+[A-Z][a-zA-Z0-9]*"
done | sort -u
Note that this will miss classes which do not follow conventions, for example which are defined in the default package or whose name do not start by a capitalized letter.
You will also retrieve classes which qualified name starts with an L : this represents arrays, and you might want to strip that L if you only care about the classname. There are other similar single-letters modifiers I can't remember.