# Spring實戰系列 - Aspect 五種通知切面通知執行順序

日常開發中經常會使用到 Spring AOP，通知類型有：Around、Before、After、AfterReturning、AfterThrowing ，本文主要講解五種通知都有時，正常和異常情況下的執行順序，以及多個切面存在時，執行順序如何

正常邏輯代碼

• 接口定義如下

public interface UserService {

    void saveUser();

    void deleteUser();
}

• 接口實現代碼如下

@Slf4j
@Component
public class UserServiceImpl implements UserService {

    @Override
    public void saveUser() {
        log.info("save user");
    }

    @Override
    public void deleteUser() {
        log.info("delete user");
        System.out.println(1 / 0);
    }
}

針對正常接口 UserService 定義兩個切面邏輯

• 切面一

@Slf4j
@Order(99)// 注意順序
@Aspect
@Component
public class UserServiceAspect {

    @Before("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void before() {
        log.info("before");
    }

    @Around("execution(* com.lushwe.aspect.service.impl..*(..))")
    public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        log.info("around開始");
        Object proceed = proceedingJoinPoint.proceed();
        log.info("around結束");
        return proceed;
    }

    @After("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void after() {
        log.info("after");
    }

    @AfterReturning("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void afterReturning() {
        log.info("afterReturning");
    }

    @AfterThrowing("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void afterThrowing() {
        log.info("afterThrowing");
    }
}

• 切面二

@Slf4j
@Order(100)// 注意順序
@Aspect
@Component
public class UserServiceAspectTwo {

    @Before("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void before() {
        log.info("before");
    }

    @Around("execution(* com.lushwe.aspect.service.impl..*(..))")
    public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        log.info("around開始");
        Object proceed = proceedingJoinPoint.proceed();
        log.info("around結束");
        return proceed;
    }

    @After("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void after() {
        log.info("after");
    }

    @AfterReturning("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void afterReturning() {
        log.info("afterReturning");
    }

    @AfterThrowing("execution(* com.lushwe.aspect.service.impl..*(..))")
    public void afterThrowing() {
        log.info("afterThrowing");
    }
}

正常情況下執行順序，打印日誌如下

2020-04-17 15:27:55.500  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspect      : around開始
2020-04-17 15:27:55.501  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspect      : before
2020-04-17 15:27:55.501  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : around開始
2020-04-17 15:27:55.501  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : before
2020-04-17 15:27:55.501  INFO 4329 --- [           main] c.l.aspect.service.impl.UserServiceImpl  : save user
2020-04-17 15:27:55.503  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : around結束
2020-04-17 15:27:55.503  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : after
2020-04-17 15:27:55.503  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : afterReturning
2020-04-17 15:27:55.503  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspect      : around結束
2020-04-17 15:27:55.503  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspect      : after
2020-04-17 15:27:55.503  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspect      : afterReturning

有異常情況下執行順序，打印日誌如下

2020-04-17 15:20:55.403  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspect      : around開始
2020-04-17 15:20:55.403  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspect      : before
2020-04-17 15:20:55.403  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : around開始
2020-04-17 15:20:55.403  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : before
2020-04-17 15:20:55.403  INFO 4227 --- [           main] c.l.aspect.service.impl.UserServiceImpl  : delete user
2020-04-17 15:20:55.403  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : after
2020-04-17 15:20:55.405  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspectTwo   : afterThrowing
2020-04-17 15:20:55.405  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspect      : after
2020-04-17 15:20:55.406  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspect      : afterThrowing
Exception in thread "main" java.lang.ArithmeticException: / by zero
...（詳細異常信息省略）...

總結

• 正常情況下執行順序：Around start -> Before -> Around end -> After -> AfterReturning
• 有異常情況下執行順序：Around start -> Before -> After -> AfterThrowing ，有異常時，Around end 邏輯不會執行
• 當有多有切面時，按照 @Order 順序依次執行，從上面日誌可以看出

---

• 本文完，希望對你有幫助