自定义类加载器

public class TestMyClassLoader {
 
	static class MyClassLoader extends ClassLoader{
 
		private String classPath;
 
		public MyClassLoader(String classPath) {
			this.classPath = classPath;
		}
 
		@Override
		protected Class findClass(String name) throws ClassNotFoundException {
			try{
				byte[] data = loadByte(name);
				return defineClass(name,data,0,data.length);
			}catch (Exception e){
				e.printStackTrace();
				throw new ClassNotFoundException();
			}
		}
 
		private byte[] loadByte(String name) throws IOException {
			name = name.replaceAll("\\.","/");
			FileInputStream fis = new FileInputStream(classPath + "/" + name + ".class");
			int len = fis.available();
			byte[] data = new byte[len];
			fis.read(data);
			fis.close();
			return data;
		}
 
		public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException {
			MyClassLoader classLoader = new MyClassLoader("D:/test");
			Class clazz = classLoader.loadClass("com.zhouyu.Parent");
			Object instance = clazz.newInstance();
			Method method = clazz.getDeclaredMethod("test");
			method.invoke(instance);
 
			System.out.println(clazz.getClassLoader().getClass().getName());
		}
	}
}