Spring AOP CGLIB代理的字段为空

CGLIB代理是Spring AOP中常用的一种代理方式。在使用CGLIB代理时，有时会遇到目标类中的字段为空的情况。本文将介绍CGLIB代理的原理，解释为何会出现字段为空的问题，并提供解决方案。最后，将通过一个案例代码来说明这个问题。

public class OrderService {
    private OrderDao orderDao;
    public void setOrderDao(OrderDao orderDao) {
        this.orderDao = orderDao;
    }
    public void createOrder() {
        // 创建订单逻辑
        orderDao.saveOrder(new Order());
    }
}

public class Main {
    public static void main(String[] args) {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(OrderService.class);
        enhancer.setCallback(new MethodInterceptor() {
            @Override
            public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
                OrderService orderService = (OrderService) obj;
                System.out.println(orderService.getOrderDao()); // 输出null
                return proxy.invokeSuper(obj, args);
            }
        });
        OrderService proxy = (OrderService) enhancer.create();
        proxy.createOrder();
    }
}

@Configurable
public class OrderService {
    @Autowired
    private OrderDao orderDao;
    public void createOrder() {
        // 创建订单逻辑
        orderDao.saveOrder(new Order());
    }
}