Re: How to find a .class file in a bunch of JARs?

From:
Alex.From.Ohio.Java@gmail.com
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 6 Aug 2008 16:35:15 -0700 (PDT)
Message-ID:
<fc44da26-4dfb-4964-8e10-498eeb898ca8@e39g2000hsf.googlegroups.com>
On Aug 6, 5:37 pm, Abhijat Vatsyayan <abhija...@optonline.net> wrote:

laredotornado wrote:

Hi,

I'm on Solaris 9. Does anyone know of a way to search through JAR
files (all of which are in the same directory) to find a class
"my.class" without having to unzip each file?

Thanks, - Dave


While on unix I will almost always use the shell, here is a quick and
dirty java based approach -

package net.abhijat.news.cl;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Collection;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class ResourceFinder
{
        private File dir ;
        private ClassLoader classLoader ;
        ResourceFinder(String dir) throws MalformedURLException
        {
                this.dir = new File(dir);
                initSelf() ;
        }
        private void initSelf() throws MalformedURLException
        {
                FileFilter fileFilter = new filter();
                File[] jarFiles = dir.listFiles(fileFilter);
                URL[] jarURLs = new URL[jarFiles.length];
                for (int i = 0; i < jarFiles.length; i++)
                {
                        File jarFile = jarFiles[i];
                        jarURLs[i] = jarFile.toURL();
                }
                classLoader = new URLClassLoader(jarURLs, null);
        }
        public Collection<String> getJarsContainingClass(String fqClassname)
throws IOException
        {
                String resName = fqClassname.replace('.', '/')+".class";
                Collection<String> jarFiles = new LinkedList<String>();
                Enumeration<URL> urls = classLoader.getResources(resName);
                while (urls.hasMoreElements())
                {
                        URL url = urls.nextElement();
                        jarFiles.add(stringForm(url));
                }
                return jarFiles;
        }
        private static String stringForm(URL jarURL)
        {
                String jarPath = jarURL.toExternalForm();
                StringTokenizer st = new StringTokenizer(jarPath, "!");
                return st.nextToken();
        }
        class filter implements FileFilter
        {
                public boolean accept(File pathname)
                {
                        if(pathname.isDirectory())
                        {
                                return false;
                        }
                        return pathname.getName().endsWith(".jar");
                }
        }
        /**
         * args[0] is the directory containing jars , args[1] is the fully
qualified classname
         * @param args
         */
        public static void main(String[] args)
        {
                try
                {
                        String dir = args[0];
                        String clsName = args[1];
                        ResourceFinder finder = new ResourceFinder(dir);
                        Collection<String> urls = finder.getJarsContainingClass(clsName);
                        for (String url : urls)
                        {
                                System.out.println("[ResourceFinder::main()] "+url);
                        }
                        System.exit(0);
                }
                catch(Exception e)
                {
                        e.printStackTrace();
                        System.exit(1);
                }
        }

}


I like JWhich better.

http://groups.google.com/group/comp.lang.java.programmer/browse_thread/thread/d3439526d8794dd6/51e2bcbc8d652c6b?hl=en&lnk=gst&q=jwhich#51e2bcbc8d652c6b

Sure, you can say it should be in classpath. But that's the point. You
may have dozens of jars with the same class and you want to know which
one exactly you are using inside your Java environment.

Alex.
http://www.myjavaserver.com/~alexfromohio/

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