private void loadFile(Map<String, Class<?>> extensionClasses, String dir) {
    //......
    BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "utf-8"));
    try {
        String line = null;
        while ((line = reader.readLine()) != null) {
            final int ci = line.indexOf('#');
            if (ci >= 0) line = line.substring(0, ci);
            line = line.trim();
            if (line.length() > 0) {
                try {
                    String name = null;
                    int i = line.indexOf('=');
                    if (i > 0) {
                        name = line.substring(0, i).trim();
                        line = line.substring(i + 1).trim();
                    }
                    if (line.length() > 0) {
                        Class<?> clazz = Class.forName(line, true, classLoader);
                        if (! type.isAssignableFrom(clazz)) {
                            throw new IllegalStateException("Error when load extension class(interface: " +
                                    type + ", class line: " + clazz.getName() + "), class " 
                                    + clazz.getName() + "is not subtype of interface.");
                        }
                        if (clazz.isAnnotationPresent(Adaptive.class)) {
                            if(cachedAdaptiveClass == null) {
                                cachedAdaptiveClass = clazz;
                            } else if (! cachedAdaptiveClass.equals(clazz)) {
                                throw new IllegalStateException("More than 1 adaptive class found: "
                                        + cachedAdaptiveClass.getClass().getName()
                                        + ", " + clazz.getClass().getName());
                            }
                        } else {
                            try {
                                clazz.getConstructor(type);
                                Set<Class<?>> wrappers = cachedWrapperClasses;
                                if (wrappers == null) {
                                    cachedWrapperClasses = new ConcurrentHashSet<Class<?>>();
                                    wrappers = cachedWrapperClasses;
                                }
                                wrappers.add(clazz);
                            } catch (NoSuchMethodException e) {
                                clazz.getConstructor();
                                if (name == null || name.length() == 0) {
                                    name = findAnnotationName(clazz);
                                    if (name == null || name.length() == 0) {
                                        if (clazz.getSimpleName().length() > type.getSimpleName().length()
                                                && clazz.getSimpleName().endsWith(type.getSimpleName())) {
                                            name = clazz.getSimpleName().substring(0, clazz.getSimpleName().length() - type.getSimpleName().length()).toLowerCase();
                                        } else {
                                            throw new IllegalStateException("No such extension name for the class " + clazz.getName() + " in the config " + url);
                                        }
                                    }
                                }
                                String[] names = NAME_SEPARATOR.split(name);
                                if (names != null && names.length > 0) {
                                    Activate activate = clazz.getAnnotation(Activate.class);
                                    if (activate != null) {
                                        cachedActivates.put(names[0], activate);
                                    }
                                    for (String n : names) {
                                        if (! cachedNames.containsKey(clazz)) {
                                            cachedNames.put(clazz, n);
                                        }
                                        Class<?> c = extensionClasses.get(n);
                                        if (c == null) {
                                            extensionClasses.put(n, clazz);
                                        } else if (c != clazz) {
                                            throw new IllegalStateException("Duplicate extension " + type.getName() + " name " + n + " on " + c.getName() + " and " + clazz.getName());
                                        }
                                    }
                                }
                            }
                        }
                    }
                } catch (Throwable t) {
                    IllegalStateException e = new IllegalStateException("Failed to load extension class(interface: " + type + ", class line: " + line + ") in " + url + ", cause: " + t.getMessage(), t);
                    exceptions.put(line, e);
                }
            }
        } // end of while read lines
    } finally {
        reader.close();
    }
    //......
}