public class Test {

    public static void main(String[] args) {
        
        // 此时三个ClassLoader是同一个对象
        System.out.println(Thread.currentThread().getContextClassLoader()); // 当前线程的类加载器
        System.out.println(Test.class.getClassLoader()); // 当前类的类加载器
        System.out.println(ClassLoader.getSystemClassLoader()); // 系统初始的类加载器
        
    }
}

------解决方案--------------------
Java code

final ClassLoader parent = findParentClassLoader();

            String libDirString = System.getProperty("openfire.lib.dir");

            File libDir;
            if (libDirString != null) {
                // If the lib directory property has been specified and it actually
                // exists use it, else use the default
                libDir = new File(libDirString);
                if (!libDir.exists()) {
                    Log.warn("Lib directory " + libDirString +
                            " does not exist. Using default " + DEFAULT_LIB_DIR);
                    libDir = new File(DEFAULT_LIB_DIR);
                }
            }
            else {
                libDir = new File(DEFAULT_LIB_DIR);
            }

            // Unpack any pack files.
            unpackArchives(libDir, true);

            String adminLibDirString = System.getProperty("openfireHome");
            if (adminLibDirString == null) {
                adminLibDirString = DEFAULT_ADMIN_LIB_DIR;
            }
            else {
                adminLibDirString = adminLibDirString+"/plugins/admin/webapp/WEB-INF/lib";
            }
            File adminLibDir = new File(adminLibDirString);
            if (adminLibDir.exists()) {
                unpackArchives(adminLibDir, false);
            }
            else {
                Log.warn("Admin Lib Directory " + adminLibDirString +
                    " does not exist. Web admin console may not work.");
            }

            ClassLoader loader = new JiveClassLoader(parent, libDir);

            Thread.currentThread().setContextClassLoader(loader);
            Class containerClass = loader.loadClass(
                    "org.jivesoftware.openfire.XMPPServer");
            containerClass.newInstance();