# Spring实战系列 - Aspect 五种通知切面通知执行顺序

日常开发中经常会使用到 Spring AOP，通知类型有：Around、Before、After、AfterReturning、AfterThrowing ，本文主要讲解五种通知都有时，正常和异常情况下的执行顺序，以及多个切面存在时，执行顺序如何

正常逻辑代码

• 接口定义如下

public interface UserService {

    void saveUser();

    void deleteUser();
}

• 接口实现代码如下

@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);
    }
}

针对正常接口 UserService 定义两个切面逻辑

• 切面一

@Slf4j
@Order(99)// 注意顺序
@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开始");
        Object proceed = proceedingJoinPoint.proceed();
        log.info("around结束");
        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)// 注意顺序
@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开始");
        Object proceed = proceedingJoinPoint.proceed();
        log.info("around结束");
        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");
    }
}

正常情况下执行顺序，打印日志如下

2020-04-17 15:27:55.500  INFO 4329 --- [           main] com.lushwe.aspect.UserServiceAspect      : around开始
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开始
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结束
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结束
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

有异常情况下执行顺序，打印日志如下

2020-04-17 15:20:55.403  INFO 4227 --- [           main] com.lushwe.aspect.UserServiceAspect      : around开始
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开始
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
...（详细异常信息省略）...

总结

• 正常情况下执行顺序：Around start -> Before -> Around end -> After -> AfterReturning
• 有异常情况下执行顺序：Around start -> Before -> After -> AfterThrowing ，有异常时，Around end 逻辑不会执行
• 当有多有切面时，按照 @Order 顺序依次执行，从上面日志可以看出

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