package com.classload.temp;

import java.io.IOException;
import java.io.InputStream;

public class MainTest {
    
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException {
        
        ClassLoader myLoader = new ClassLoader(){
            @Override
            public Class<?> loadClass(String name) throws ClassNotFoundException {

                try {
                    String fileName = name.substring(name.lastIndexOf(".") + 1) + ".class";
                    InputStream is = getClass().getResourceAsStream(fileName);
                    if(is == null){
                        return super.loadClass(name);
                    }
                    
                    byte[] b = new byte[is.available()];
                    is.read(b);
                    return defineClass(name, b, 0, b.length);
                } catch (IOException e) {
                    throw new ClassNotFoundException(name);
                }
            }
        };
        
        Object obj = myLoader.loadClass("com.classload.temp.MainTest").newInstance();
        System.out.println(obj.getClass());
        System.out.println(obj instanceof com.classload.temp.MainTest);
        
        /**
         * 执行结果: 
         *    class com.classload.temp.MainTest
         *    false                                  //obj使用了myLoader自定义类加载器，MainTest使用了应用程序类加载器，加载器不用所以为false
         */
    }
}