/*
 * Copyright 1999-2018 Alibaba Group Holding Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.druid.support.logging;

/**
 * A class to simplify access to resources through the classloader.
 */
public final class Resources extends Object {
    private static ClassLoader defaultClassLoader;

    private Resources() {
    }

    /**
     * Returns the default classloader (may be null).
     *
     * @return The default classloader
     */
    public static ClassLoader getDefaultClassLoader() {
        return defaultClassLoader;
    }

    /**
     * Sets the default classloader
     *
     * @param defaultClassLoader - the new default ClassLoader
     */
    public static void setDefaultClassLoader(ClassLoader defaultClassLoader) {
        Resources.defaultClassLoader = defaultClassLoader;
    }

    /**
     * Loads a class
     *
     * @param className - the class to load
     * @return The loaded class
     * @throws ClassNotFoundException If the class cannot be found (duh!)
     */
    public static Class<?> classForName(String className) throws ClassNotFoundException {
        Class<?> clazz = null;
        try {
            clazz = getClassLoader().loadClass(className);
        } catch (Exception e) {
            // Ignore. Failsafe below.
        }
        if (clazz == null) {
            clazz = Class.forName(className);
        }
        return clazz;
    }

    private static ClassLoader getClassLoader() {
        if (defaultClassLoader != null) {
            return defaultClassLoader;
        } else {
            return Thread.currentThread().getContextClassLoader();
        }
    }

}
