Java在运行期加载jar包

JarFile jarFile = new JarFile(pathToJar);
Enumeration<JarEntry> e = jarFile.entries();

URL[] urls = { new URL("jar:file:" + pathToJar+"!/") };
URLClassLoader cl = URLClassLoader.newInstance(urls);

while (e.hasMoreElements()) {
    JarEntry je = e.nextElement();
    if(je.isDirectory() || !je.getName().endsWith(".class")){
        continue;
    }
    // -6 because of .class
    String className = je.getName().substring(0,je.getName().length()-6);
    className = className.replace('/', '.');
    Class c = cl.loadClass(className);

}