Dynamic Proxy Implementtaion

/**
 * @author Li Yajie
 * @date 2024/4/7 10:57
 * @description ProxyUtil
 */
public class ProxyUtil {
    /**
     * JDK Dynamic Proxy
     *
     * @param target   Target object to be proxied
     * @param <T>
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <T> T createJDKProxy(@NotNull T target) {
        return (T) Proxy.newProxyInstance(target.getClass().getClassLoader(),
                target.getClass().getInterfaces(),
                (proxy, method, args) -> method.invoke(target, args)
        );
    }

   /**
     *
     * @param target   Target object for proxy
     * @param before   Before notification action
     * @param after    After notification action
     * @return         Proxied instance
     * @param <T>
     */
    @SuppressWarnings("unchecked")
    public static <T> T createCglibProxy(@NotNull T target, Runnable before, Runnable after) {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(target.getClass());
        enhancer.setCallback((MethodInterceptor) (obj, method, args, proxy) -> {
            before.run();
            Object result = proxy.invokeSuper(obj, args);
            after.run();
            return result;
        });
        return (T) enhancer.create();
    }

}

Test method

@Test
    public void test02(){
        UserServiceImpl service = new UserServiceImpl();
        UserServiceImpl proxy = ProxyUtil.createCglibProxy(service,
                ()-> System.out.println("Before notification"),
                () -> System.out.println("After notification")
        );
        proxy.insert(new User());
    }

Output

The function interface can also be changed to Function<T,R> to achieve pre-interception.

Code example:

@SuppressWarnings("unchecked")
    public static <T> T createCglibProxy(@NotNull T target, Function<Object[],Boolean> before, Runnable after) {
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(target.getClass());
        enhancer.setCallback((MethodInterceptor) (obj, method, args, proxy) -> {
            if (!before.apply(args)) {
                return null;
            }
            Object result = proxy.invokeSuper(obj, args);
            after.run();
            return result;
        });
        return (T) enhancer.create();
    }

Test code

@Test
    public void test02() {
        UserServiceImpl service = new UserServiceImpl();
        UserServiceImpl proxy = ProxyUtil.createCglibProxy(service,
                (args) -> {
                    System.out.println("Pre-interception");
                    User user = (User) args[0];
                    return user != null;
                },
                () -> System.out.println("After notification")
        );
        proxy.insert(null);
        System.out.println("_________");
        proxy.insert(new User());
    }

Test output

Interception behavior achieved through a functioanl itnerface returning a value