说明

说到对类方法增强，第一时间想到自定义注解，通过aop切面进行实现。这是一种常用做法，但是在某些场景下，如开发公共组件，定义aop切面可能不是最优方案。以后通过原生aop方式，自定义注解，对类方法进行增强。

实现

自定义注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CustomStat {
}

自定义切点

/*** 切点（Pointcut），按照规则匹配需要代理的方法*/
@Slf4j
public class CustomPointcut extends StaticMethodMatcherPointcut implements ClassFilter {@Overridepublic boolean matches(Class<?> clazz) {boolean contains = clazz.getName().contains("com.spring.demo.service");if (contains) {log.info("CustomPointcut:{}",clazz.getName());}return contains;}@Overridepublic boolean matches(Method method, Class<?> targetClass) {boolean contains = targetClass.getName().contains("com.spring.demo.service");if (contains) {log.info("CustomPointcut:{}",targetClass.getName());}return contains;}
}

自定义增强器

public class CustomAnnotationAdvisor extends AbstractPointcutAdvisor implements BeanFactoryAware, Ordered {private Advice advice;private Pointcut pointcut;private MethodInterceptor methodInterceptor;public CustomAnnotationAdvisor(MethodInterceptor methodInterceptor) {this.methodInterceptor = methodInterceptor;this.advice = buildAdvice();this.pointcut = buildPointcut();}@Overridepublic Pointcut getPointcut() {return this.pointcut;}@Overridepublic Advice getAdvice() {return this.advice;}@Overridepublic void setBeanFactory(BeanFactory beanFactory) throws BeansException {if (this.advice instanceof BeanFactoryAware) {((BeanFactoryAware) this.advice).setBeanFactory(beanFactory);}}protected Advice buildAdvice() {return methodInterceptor;}protected Pointcut buildPointcut() {//构建切点Pointcut cpc = new AnnotationMatchingPointcut(CustomStat.class, true);Pointcut mpc = AnnotationMatchingPointcut.forMethodAnnotation(CustomStat.class);return new ComposablePointcut(cpc).union(mpc);}@Overridepublic int getOrder() {return Integer.MAX_VALUE;}
}

其中构造参数中的MethodInterceptor为最终代理拦截器

自定义拦截器

@Slf4j
@Component
public class CustomAnnotationInterceptor implements MethodInterceptor {@Overridepublic Object invoke(MethodInvocation invocation) throws Throwable {//调用的方法和参数//Method method = invocation.getMethod();// Object[] arguments = invocation.getArguments();log.info("start-注解aop拦截器");Object proceed = invocation.proceed();log.info("end-注解aop拦截器");return proceed;}
}

注册增强器

@Component
public class CustomAnnotationBeanPostProcessor extends AbstractAdvisingBeanPostProcessor implements BeanFactoryAware {@Resourceprivate CustomAnnotationInterceptor customAnnotationInterceptor;@Overridepublic void setBeanFactory(BeanFactory beanFactory) throws BeansException {setBeforeExistingAdvisors(true);CustomAnnotationAdvisor advisor = new CustomAnnotationAdvisor(customAnnotationInterceptor);advisor.setBeanFactory(beanFactory);this.advisor = advisor;}
}

测试

    @Override@CustomStatpublic void printWork() {System.out.println("WorkServiceImpl1");}

结果

2024-05-21 08:55:26.486  INFO 41351 --- [nio-8081-exec-5] c.s.d.a.CustomAnnotationInterceptor      : start-注解aop拦截器
WorkServiceImpl1
2024-05-21 08:55:26.486  INFO 41351 --- [nio-8081-exec-5] c.s.d.a.CustomAnnotationInterceptor      : end-注解aop拦截器