自定义类加载器

最新推荐文章于 2025-11-24 14:38:27 发布

原创最新推荐文章于 2025-11-24 14:38:27 发布 · 212 阅读

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#java #前端 #开发语言

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本文介绍了如何在Java中创建一个自定义的ClassLoader，通过`MyClassLoader`实现按指定路径加载`com.zhouyu.Parent`类并调用其方法。

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());
		}
	}
}