LibsDisguises/src/me/libraryaddict/disguise/utilities/ClassGetter.java

package me.libraryaddict.disguise.utilities;

import java.net.URL;
import java.net.URLDecoder;
import java.security.CodeSource;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.bukkit.entity.Entity;

/**
 * User: Austin Date: 4/22/13 Time: 11:47 PM (c) lazertester
 */
// Code for this taken and slightly modified from
// https://github.com/ddopson/java-class-enumerator
public class ClassGetter
{

    public static ArrayList<Class<?>> getClassesForPackage(String pkgname)
    {
        ArrayList<Class<?>> classes = new ArrayList<>();
        // String relPath = pkgname.replace('.', '/');

        // Get a File object for the package
        CodeSource src = Entity.class.getProtectionDomain().getCodeSource();

        if (src != null)
        {
            URL resource = src.getLocation();
            resource.getPath();
            processJarfile(resource, pkgname, classes);
        }

        return classes;
    }

    private static Class<?> loadClass(String className)
    {
        try
        {
            return Class.forName(className);
        }
        catch (ClassNotFoundException e)
        {
            throw new RuntimeException("Unexpected ClassNotFoundException loading class '" + className + "'");
        }
        catch (NoClassDefFoundError e)
        {
            return null;
        }
    }

    private static void processJarfile(URL resource, String pkgname, ArrayList<Class<?>> classes)
    {
        try
        {
            String relPath = pkgname.replace('.', '/');
            String resPath = URLDecoder.decode(resource.getPath(), "UTF-8");
            String jarPath = resPath.replaceFirst("[.]jar[!].*", ".jar").replaceFirst("file:", "");
            JarFile jarFile = new JarFile(jarPath);
            Enumeration<JarEntry> entries = jarFile.entries();
            while (entries.hasMoreElements())
            {
                JarEntry entry = entries.nextElement();
                String entryName = entry.getName();
                String className = null;
                if (entryName.endsWith(".class") && entryName.startsWith(relPath)
                        && entryName.length() > (relPath.length() + "/".length()))
                {
                    className = entryName.replace('/', '.').replace('\\', '.').replace(".class", "");
                }
                if (className != null)
                {
                    Class<?> c = loadClass(className);
                    if (c != null)
                    {
                        classes.add(c);
                    }
                }
            }
        }
        catch (Exception ex)
        {
            ex.printStackTrace(System.out);
        }
    }
}