How to fully release/close a loaded jar ?

I'm looking for a solution to release a loaded jar from the memory. The following code shows how I tried it so far. Any better ideas?
thx
`import org.xeustechnologies.jcl.JarClassLoader;
import java.io.IOException; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.util.ArrayList; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.Vector; import java.util.jar.JarFile;
public class JarLoader extends JarClassLoader{
protected HashSet<String> setJarFileNames2Close = new HashSet<String>();

public void release(){
    close();
    loaders.clear();
    classes.clear();
}

public void close() {
    setJarFileNames2Close.clear();
    closeClassLoader(this);
    finalizeNativeLibs(this);
    cleanupJarFileFactory();
}

/**
 * cleanup jar file factory cache
 */
@SuppressWarnings({ "nls", "unchecked" })
public boolean cleanupJarFileFactory()
{
    boolean res = false;
    Class classJarURLConnection = null;
    try {
        classJarURLConnection = Class.forName("sun.net.www.protocol.jar.JarURLConnection");
    } catch (ClassNotFoundException e) {
        //ignore
    }
    if (classJarURLConnection == null) {
        return res;
    }
    Field f = null;
    try {
        f = classJarURLConnection.getDeclaredField("factory");
    } catch (NoSuchFieldException e) {
        //ignore
    }
    if (f == null) {
        return res;
    }
    f.setAccessible(true);
    Object obj = null;
    try {
        obj = f.get(null);
    } catch (IllegalAccessException e) {
        //ignore
    }
    if (obj == null) {
        return res;
    }
    Class classJarFileFactory = obj.getClass();
    //
    HashMap fileCache = null;
    try {
        f = classJarFileFactory.getDeclaredField("fileCache");
        f.setAccessible(true);
        obj = f.get(null);
        if (obj instanceof HashMap) {
            fileCache = (HashMap)obj;
        }
    } catch (NoSuchFieldException e) {
    } catch (IllegalAccessException e) {
        //ignore
    }
    HashMap urlCache = null;
    try {
        f = classJarFileFactory.getDeclaredField("urlCache");
        f.setAccessible(true);
        obj = f.get(null);
        if (obj instanceof HashMap) {
            urlCache = (HashMap)obj;
        }
    } catch (NoSuchFieldException e) {
    } catch (IllegalAccessException e) {
        //ignore
    }
    if (urlCache != null) {
        HashMap urlCacheTmp = (HashMap)urlCache.clone();
        Iterator it = urlCacheTmp.keySet().iterator();
        while (it.hasNext()) {
            obj = it.next();
            if (!(obj instanceof JarFile)) {
                continue;
            }
            JarFile jarFile = (JarFile)obj;
            if (setJarFileNames2Close.contains(jarFile.getName())) {
                try {
                    jarFile.close();
                } catch (IOException e) {
                    //ignore
                }
                if (fileCache != null) {
                    fileCache.remove(urlCache.get(jarFile));
                }
                urlCache.remove(jarFile);
            }
        }
        res = true;
    } else if (fileCache != null) {
        // urlCache := null
        HashMap fileCacheTmp = (HashMap)fileCache.clone();
        Iterator it = fileCacheTmp.keySet().iterator();
        while (it.hasNext()) {
            Object key = it.next();
            obj = fileCache.get(key);
            if (!(obj instanceof JarFile)) {
                continue;
            }
            JarFile jarFile = (JarFile)obj;
            if (setJarFileNames2Close.contains(jarFile.getName())) {
                try {
                    jarFile.close();
                } catch (IOException e) {
                    //ignore
                }
                fileCache.remove(key);
            }
        }
        res = true;
    }
    setJarFileNames2Close.clear();
    return res;
}

/**
 * close jar files of cl
 * @param cl
 * @return
 */
@SuppressWarnings( { "nls", "unchecked" })
public boolean closeClassLoader(ClassLoader cl) {
    boolean res = false;
    if (cl == null) {
        return res;
    }
    Class classURLClassLoader = JarLoader.class;
    Field f = null;
    try {
        f = classURLClassLoader.getDeclaredField("ucp");
    } catch (NoSuchFieldException e1) {
        //ignore
    }
    if (f != null) {
        f.setAccessible(true);
        Object obj = null;
        try {
            obj = f.get(cl);
        } catch (IllegalAccessException e1) {
            //ignore
        }
        if (obj != null) {
            final Object ucp = obj;
            f = null;
            try {
                f = ucp.getClass().getDeclaredField("loaders");
            } catch (NoSuchFieldException e1) {
                //ignore
            }
            if (f != null) {
                f.setAccessible(true);
                ArrayList loaders = null;
                try {
                    loaders = (ArrayList) f.get(ucp);
                    res = true;
                } catch (IllegalAccessException e1) {
                    //ignore
                }
                for (int i = 0; loaders != null && i < loaders.size(); i++) {
                    obj = loaders.get(i);
                    f = null;
                    try {
                        f = obj.getClass().getDeclaredField("jar");
                    } catch (NoSuchFieldException e) {
                        //ignore
                    }
                    if (f != null) {
                        f.setAccessible(true);
                        try {
                            obj = f.get(obj);
                        } catch (IllegalAccessException e1) {
                            // ignore
                        }
                        if (obj instanceof JarFile) {
                            final JarFile jarFile = (JarFile)obj;
                            setJarFileNames2Close.add(jarFile.getName());
                            //try {
                            //  jarFile.getManifest().clear();
                            //} catch (IOException e) {
                            //  // ignore
                            //}
                            try {
                                jarFile.close();
                            } catch (IOException e) {
                                // ignore
                            }
                        }
                    }
                }
            }
        }
    }
    return res;
}

/**
 * finalize native libraries
 * @param cl
 * @return
 */
@SuppressWarnings({ "nls", "unchecked" })
public boolean finalizeNativeLibs(ClassLoader cl) {
    boolean res = false;
    Class classClassLoader = ClassLoader.class;
    java.lang.reflect.Field nativeLibraries = null;
    try {
        nativeLibraries = classClassLoader.getDeclaredField("nativeLibraries");
    } catch (NoSuchFieldException e1) {
        //ignore
    }
    if (nativeLibraries == null) {
        return res;
    }
    nativeLibraries.setAccessible(true);
    Object obj = null;
    try {
        obj = nativeLibraries.get(cl);
    } catch (IllegalAccessException e1) {
        //ignore
    }
    if (!(obj instanceof Vector)) {
        return res;
    }
    res = true;
    Vector java_lang_ClassLoader_NativeLibrary = (Vector)obj;
    for (Object lib : java_lang_ClassLoader_NativeLibrary) {
        java.lang.reflect.Method finalize = null;
        try {
            finalize = lib.getClass().getDeclaredMethod("finalize", new Class[0]);
        } catch (NoSuchMethodException e) {
            //ignore
        }
        if (finalize != null) {
            finalize.setAccessible(true);
            try {
                finalize.invoke(lib, new Object[0]);
            } catch (IllegalAccessException e) {
            } catch (InvocationTargetException e) {
                //ignore
            }
        }
    }
    return res;
}
} `
kamranzafar / JCL

How to fully release/close a loaded jar ? #55
