解决URLClassLoader使用addURL方法失效的问题

public void addURL(URL u) {
    URLClassLoader sysLoader = (URLClassLoader) this.getClass().getClassLoader();
    URL urls[] = sysLoader.getURLs();
    for (int i = 0; i < urls.length; i++) { // 过滤已加载的jar文件
        if (urls[i].toString().equalsIgnoreCase(u.toString())) {
            return;
        }
    }
    Class sysclass = URLClassLoader.class;
    try {
        Method method = sysclass.getDeclaredMethod("addURL", URL.class);
        method.setAccessible(true);
        method.invoke(sysLoader, new Object[]{u});
    } catch (Throwable t) {
        LOGGER.error("Error, could not add URL to system classloader", t);
    }
}