自定义类加载器

package com.spasvo.test;

import java.io.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.file.Files;

class MyClassLoader extends ClassLoader{
    @Override
    protected Class<?> findClass(String name) throws ClassNotFoundException {
        File file = new File("E:\\Person.class");
        try {
            byte[] bytes = Files.readAllBytes(file.toPath());
            return defineClass("Person",bytes,0,bytes.length);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

public class Main {
    public static void main(String[] args)  {

        MyClassLoader loader = new MyClassLoader();
        Class<?> cl = null;
        try {
            cl = loader.loadClass("Person");
            Method method = cl.getMethod("ifElseTest",int.class);
            Object instance = cl.newInstance();
            method.invoke(instance,12);
        } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InstantiationException | InvocationTargetException e) {
            e.printStackTrace();
        }

    }
}

测试类

public class Person {
    public String name;
    
    public int age;
    public void funcForTest(String testParma1,int testParma2){
        for (int i = 0; i < 10; i++) {
        	//报错句子
            System.out.println("for test");
        }

    }
    public void ifElseTest(int name){
        if(name == 1){
            System.out.println("if test");
        }else if(name == 2){
            System.out.println("else if test");
        }else {
            System.out.println("else test");
        }
    }
    public void whileTest(){
        while (true){
            System.out.println("while test");
        }
    }
    public void tryCatchTest(){
        try {
            System.out.println("try test");
        }catch (Exception e){
            System.out.println("catch test");
        }finally {
            System.out.println("finally test");
        }
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

运行结果

else test

Process finished with exit code 0