Java中如何自定义一个类加载器加载自己指定的类

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class MyClassLoader extends ClassLoader {
    
    private String classPath;

    // 构造方法，指定加载路径
    public MyClassLoader(String classPath) {
        this.classPath = classPath;
    }

    // 重写 findClass 方法
    @Override
    protected Class<?> findClass(String name) throws ClassNotFoundException {
        byte[] classData = loadClassData(name);
        if (classData == null) {
            throw new ClassNotFoundException();
        }
        return defineClass(name, classData, 0, classData.length);
    }

    // 自定义读取类数据的方法
    private byte[] loadClassData(String className) {
        try {
            // 将包名中的 . 替换为路径分隔符 /
            String fileName = classPath + className.replace('.', '/') + ".class";
            FileInputStream fis = new FileInputStream(new File(fileName));
            byte[] data = new byte[fis.available()];
            fis.read(data);
            fis.close();
            return data;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
}

public class Main {
    public static void main(String[] args) {
        String classPath = "/my/custom/classes/";
        MyClassLoader myClassLoader = new MyClassLoader(classPath);

        try {
            // 加载 com.example.HelloWorld 类
            Class<?> clazz = myClassLoader.loadClass("com.example.HelloWorld");
            Object instance = clazz.newInstance();
            System.out.println("加载成功！" + instance.getClass().getName());
        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        }
    }
}