java 通过反射调用main方法

我们可以通过绝对路径让URLClassLoader，加载一个程序外部的 .class文件并调用其main方法

public class Test {
    public static void main(String[] args) throws InterruptedException {
        Test test = new Test();
        test.say();
    }

    public void say() throws InterruptedException {
        int i = 0;
        while (true) {
            i++;
            if (i >= 100) {
                break;
            }
            Thread.sleep(1000);
            System.out.println("hello");
        }
    }
}

package com;

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 Hello {
    public static void main(String[] args)
            throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException,
            IllegalAccessException, IllegalArgumentException, InvocationTargetException, MalformedURLException {
        File file = new File("../Test.class");
        URL[] urls = new URL[1];
        urls[0] = file.toURL();
        URLClassLoader classLoader = new URLClassLoader(urls);
        System.out.println(classLoader);
        Class mClass = classLoader.loadClass("Test");
        Object test = mClass.newInstance();
        Method m1 = mClass.getMethod("main", String[].class);
        m1.invoke(null, (Object) new String[] { "a", "b", "c" });
    }
}