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Find a Class in Jars

I often have to find a class (or its different occurrences) in a list of jars located in a folder (or its sub-folders). The Jython script below parses all the jars in a location, and display the name of all the jars containing the class I’m looking for. Stick it into a file called “search_jar.py.”

import os, sys, traceback

from os.path import isdir,join

from java.util.zip import *

from java.util.jar import *

from java.io import *


	
def scan_directory(class_name, directory=’.’):
        for f in os.listdir(directory):
                if os.path.isdir(join(directory, f)):
                        scan_directory(class_name, join(directory, f))
                if os.path.basename(f).lower().endswith(’.jar’) > 0 \
                and not os.path.isdir(join(directory, f)):
                        scan_jar(class_name, join(directory, f))

	
def scan_jar(class_name, jar_file):
        try:
                jar = JarFile(jar_file)
                entries = jar.entries()
                while entries.hasMoreElements():
                        entry = entries.nextElement()
                        if entry.toString().find(class_name) >= 0:
                                print ‘%s: %s’ \
                                % (os.path.abspath(jar_file), entry)

        except ZipException:
                print ‘Error trying to open %s’ % jar_file
                traceback.print_exc(file=sys.stdout)

	
if name  '__main__':
    if not len(sys.argv)  3:
        print “Usage: jython search_jar.py  “
        sys.exit(1)
    scan_directory(sys.argv[1] + '.class', sys.argv[2])

It can be called as follows:

jython search_jar.py MyNiceStub C:\application_server\lib

This script is quite handy when investigating issues related to ClassNotFoundException, or ClassCastException, or classloading-related problems. Watch out, the script appends “.class” to the name of the class you’re passing to the script, so if you’re looking for something other than a class (a resource file, for example), it won’t find it. It doesn’t look for classes which are not in jars either – but adding this to the script is trivial!