SpringBoot项目中JDK动态代理和CGLIB动态代理的使用详解

// 接口
interface MyInterface {
    void doSomething();
}

// 实现类
class MyClass implements MyInterface {
    @Override
    public void doSomething() {
        System.out.println("MyClass is doing something...");
    }
}

// 调用处理器
class MyInvocationHandler implements InvocationHandler {
    private Object target; // 被代理的对象

    public MyInvocationHandler(Object target) {
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("Before method: " + method.getName()); // 前置增强
        Object result = method.invoke(target, args); // 调用原始方法
        System.out.println("After method: " + method.getName()); // 后置增强
        return result;
    }
}

// 使用 JDK 动态代理
public class JDKDynamicProxyExample {
    public static void main(String[] args) {
        MyInterface target = new MyClass(); // 创建目标对象
        MyInvocationHandler handler = new MyInvocationHandler(target); // 创建调用处理器

        // 创建代理对象
        MyInterface proxy = (MyInterface) Proxy.newProxyInstance(
                MyInterface.class.getClassLoader(),
                new Class[] {MyInterface.class},
                handler
        );

        proxy.doSomething(); // 调用代理对象的方法，会被拦截
    }
}

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

// 目标类
class MyClass {
    public void doSomething() {
        System.out.println("MyClass is doing something...");
    }
}

// 方法拦截器
class MyMethodInterceptor implements MethodInterceptor {
    @Override
    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
        System.out.println("Before method: " + method.getName()); // 前置增强
        Object result = proxy.invokeSuper(obj, args); // 调用原始方法
        System.out.println("After method: " + method.getName()); // 后置增强
        return result;
    }
}

// 使用 CGLIB 动态代理
public class CGLIBDynamicProxyExample {
    public static void main(String[] args) {
        Enhancer enhancer = new Enhancer(); // 创建 Enhancer 对象
        enhancer.setSuperclass(MyClass.class); // 设置超类
        enhancer.setCallback(new MyMethodInterceptor()); // 设置回调

        MyClass proxy = (MyClass) enhancer.create(); // 创建代理对象

        proxy.doSomething(); // 调用代理对象的方法，会被拦截
    }
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-aop</artifactId>
</dependency>

@Aspect
@Component
public class LoggingAspect {

    @Before("execution(* com.example.demo.service.*.*(..))")
    public void beforeAdvice(JoinPoint joinPoint) {
        System.out.println("Before executing method: " + joinPoint.getSignature());
    }
}

@Configuration
@EnableAspectJAutoProxy(proxyTargetClass = true) // 强制使用 CGLIB 动态代理
public class AopConfig {
    // ...
}

@EnableAspectJAutoProxy(proxyTargetClass = true)