学步园

//一个通告或建议的接口
public interface Advice {
	void afterMethod(Method method);
	void beforeMethod(Method method);
}

public class MyAdvice implements Advice{
	private long start;
	@Override
	public void afterMethod(Method method) {
		System.out.println("运行时间计算结束!!");
		System.out.println("共耗时:"+(System.currentTimeMillis()-start));
		System.out.println("------------------------");
	}
	@Override
	public void beforeMethod(Method method) {
		System.out.println("开始计算运行时间:");
		start=System.currentTimeMillis();
		System.out.println("所执行的方法:"+method.getName());
	}
}

//编写可生成代理和插入通告的通用方法
public class Test1 {
	public static void main(String[] args) {
		final List target=new ArrayList();
		Collection coll = (Collection) getProxy(target,new MyAdvice());
		coll.add("111");
		coll.add("222");
		coll.add("333");
		System.out.println(coll.size());
	}
	
	//抽象出一个公共的方法
	private static Object getProxy(final Object target,final Advice advice) {
		Object coll=(Object) Proxy.newProxyInstance(
				target.getClass().getClassLoader(), 
				target.getClass().getInterfaces(), 
				new InvocationHandler(){
					@Override
					public Object invoke(Object proxy, Method method,
							Object[] args) throws Throwable {
						advice.beforeMethod(method);
						Object obj=method.invoke(target, args);
						advice.afterMethod(method);
						return obj;
					}
				});
		return coll;
	}
}