动态代理简单代码

/**
 * 业务接口
 */
public interface Subject {
    void call();
}

/**
 * 业务接口的实现（被代理的类）
 */
public class RealSubjcet implements Subject {
    @Override
    public void call() {
        Log.d("denny", "RealSubject#call");
    }
}

/**
 * 代理类
 */
public class ProxyHandler implements InvocationHandler {

    private final Object realSubject;

    public ProxyHandler(Object realSubject) {
        this.realSubject = realSubject;
    }

    @Override
    public Object invoke(Object o, Method method, Object[] args) throws Throwable {
        Log.d("denny", "before ProxyHandler#invoke");
        Object result = method.invoke(realSubject, args);
        Log.d("denny", "after ProxyHandler#invoke");
        return result;
    }
}

// 通过Proxy创建代理类对象
RealSubjcet realSubjcet = new RealSubjcet();
Subject proxySubject = (Subject) Proxy.newProxyInstance(
        Subject.class.getClassLoader(),
        new Class[]{Subject.class},
        new ProxyHandler(realSubjcet));
proxySubject.call();

以及，最终的结果：

D/denny: before ProxyHandler#invoke

D/denny: RealSubject#call

D/denny: after ProxyHandler#invoke