Java Utililty Methods Class Loader

boolean addDirectoryToClassLoader(ClassLoader loader, File directory)
add Directory To Class Loader

try {
 ClassLoader rootLoader = getRootLoader(loader);
 if (rootLoader == null) {
 return false;
 } else {
 URL url = directory.toURI().toURL();
 Method method = rootLoader.getClass().getMethod("addURL", URL.class);
 method.invoke(rootLoader, url);
...

void addFileToSystemClassLoader(String s)
add File To System Class Loader

File f = new File(s);
addFileToSystemClassLoader(f);

ClassLoader createClassloader(File libDir, ClassLoader cl)
Create a class loader that can load classes from the specified file directory.

URLClassLoader urlClassloader = null;
if (libDir.exists()) {
 if (libDir.isDirectory()) {
 String[] jars = libDir.list(new FilenameFilter() {
 public boolean accept(File dir, String name) {
 return name.endsWith(".jar") || name.endsWith(".zip");
 });
...

URLClassLoader createClassLoader(File root)
create Class Loader

return new URLClassLoader(new URL[] { root.toURI().toURL() },
 Thread.currentThread().getContextClassLoader());

ClassLoader createClassLoader(final String[] cpEntries)
Builds a ClassLoader for a given classpath.

final URL[] cpUrls = new URL[cpEntries.length];
for (int i = 0; i < cpEntries.length; i++) {
 String cpEntry = cpEntries[i];
 File entry = new File(cpEntry);
 try {
 URL url = entry.toURI().toURL();
 cpUrls[i] = url;
 } catch (MalformedURLException ex) {
...

URLClassLoader createClassLoader(String fileName)
create Class Loader

String urlPath = makeUrlPath(fileName);
URL url = null;
try {
 url = new URL(urlPath);
} catch (MalformedURLException e) {
 throw new RuntimeException(e);
URLClassLoader loader = URLClassLoader.newInstance(new URL[] { url });
...

URLClassLoader createFallbackClassLoader(Collection files)
create Fallback Class Loader

List<URL> urls = new ArrayList<URL>(files.size());
for (File file : files) {
 urls.add(file.toURI().toURL());
return new URLClassLoader(urls.toArray(new URL[urls.size()]), null);

void dumpClassLoader(ClassLoader cl, PrintWriter out)
dump Class Loader

int level = 0;
while (cl != null) {
 String msg = "Servlet ClassLoader[" + level + "]: " + cl.getClass().getName() + ':' + cl.hashCode();
 out.println(msg);
 URL[] urls = getClassLoaderURLs(cl);
 msg = " URLs:";
 out.println(msg);
 for (int u = 0; u < urls.length; u++) {
...

Class getClass(Object classLoaderMakedObject, File file, String targetClass)
get Class

URL[] urls = { file.toURI().toURL() };
URLClassLoader classLoader = (URLClassLoader) classLoaderMakedObject.getClass().getClassLoader();
ClassLoader loader = URLClassLoader.newInstance(urls, classLoader);
Class<?> clazz = loader.loadClass(targetClass);
return clazz;

InputStream getClassInputStream(String className, ClassLoader cl)
get Class Input Stream

return cl.getResourceAsStream(classToResource(className));