package cn.baokx.test_addjar;

import java.io.File;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;

public class Main {
	public static void main(String[] args) throws NoSuchMethodException,
			SecurityException, MalformedURLException, ClassNotFoundException,
			InstantiationException, IllegalAccessException,
			IllegalArgumentException, InvocationTargetException {
		loadJar(Main.class.getResource("/lib/test.jar").getPath());
		Class clazz = Class.forName("cn.baokx.testjar.Demo1");
		Object obj = clazz.newInstance();
		Method method = clazz.getMethod("fun1");
		method.invoke(obj);
	}

	public static void loadJar(String jarPath) {
		File jarFile = new File(jarPath);
		// 從URLClassLoader類中獲取類所在資料夾的方法，jar也可以認為是一個資料夾
		Method method = null;
		try {
			method = URLClassLoader.class
					.getDeclaredMethod("addURL", URL.class);
		} catch (NoSuchMethodException | SecurityException e1) {
			e1.printStackTrace();
		}
		// 獲取方法的訪問許可權以便寫回
		boolean accessible = method.isAccessible();
		try {
			method.setAccessible(true);
			// 獲取系統類載入器
			URLClassLoader classLoader = (URLClassLoader) ClassLoader
					.getSystemClassLoader();
			URL url = jarFile.toURI().toURL();
			method.invoke(classLoader, url);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			method.setAccessible(accessible);
		}
	}
}