public static void main(String[] args)

            throws IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException,

            SecurityException, ClassNotFoundException, InstantiationException, MalformedURLException {

//         String path =

//         "/xx/.m2/repository/org/apache/commons/commons-lang3/3.1/commons-lang3-3.1.jar";

        String path = "commons-lang3-3.1.jar";//jar文件需放在工程目录下

        loadJar(path);

        Class<?> aClass = Class.forName("org.apache.commons.lang3.StringUtils");

        Object instance = aClass.newInstance();

        Object strip = aClass.getDeclaredMethod("strip", String.class, String.class).invoke(instance,

                "[1,2,3,4,5,6,2,3,5,1]", "[]");

        System.out.println(strip);

    }

    private static void loadJar(String jarPath) throws MalformedURLException {

        File jarFile = new File(jarPath); // 从URLClassLoader类中获取类所在文件夹的方法，jar也可以认为是一个文件夹

        if (jarFile.exists() == false) {

            System.out.println("jar file not found.");

            return;

        }

        //获取类加载器的addURL方法，准备动态调用

        Method method = null;

        try {

            method = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);

        } catch (NoSuchMethodException | SecurityException e1) {

            e1.printStackTrace();

        } 

        // 获取方法的访问权限，保存原始值

        boolean accessible = method.isAccessible();

        try {

            //修改访问权限为可写

            if (accessible == false) {

                method.setAccessible(true);

            }

            // 获取系统类加载器

            URLClassLoader classLoader = (URLClassLoader) ClassLoader.getSystemClassLoader();

            //获取jar文件的url路径

            java.net.URL url = jarFile.toURI().toURL();

            //jar路径加入到系统url路径里

            method.invoke(classLoader, url);

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            //回写访问权限

            method.setAccessible(accessible);

        }

    }