深度解析Spring AOP @Aspect 原理、实战与最佳实践教程

@Aspect
@Component
@Order(1) // 控制多个切面的执行顺序
@Slf4j
public class LoggingAspect {
    // 定义可重用的切入点表达式
    @Pointcut("execution(* com.example.service.*.*(..))")
    public void serviceLayer() {}
    @Before("serviceLayer()")
    public void logMethodStart(JoinPoint jp) {
        log.info("▶️ 调用 {}.{} 参数: {}",
            jp.getTarget().getClass().getSimpleName(),
            jp.getSignature().getName(),
            Arrays.toString(jp.getArgs()));
    }
    @Around("@annotation(com.example.audit.AuditLog)")
    public Object auditLog(ProceedingJoinPoint pjp) throws Throwable {
        long start = System.currentTimeMillis();
        Object result = pjp.proceed();
        log.info("🕑 审计日志 - 操作: {}, 耗时: {}ms",
            pjp.getSignature().getName(),
            System.currentTimeMillis() - start);
        return result;
    }
    @AfterThrowing(pointcut = "serviceLayer()", throwing = "ex")
    public void logException(JoinPoint jp, Exception ex) {
        log.error("⚠️ 方法 {} 抛出异常: {}", 
            jp.getSignature(), ex.getMessage());
    }
}

@Aspect
@Component
public class RateLimitAspect {
    private final RateLimiter limiter = RateLimiter.create(100); // 100 QPS
    @Around("@annotation(rateLimit)")
    public Object limit(ProceedingJoinPoint pjp, RateLimit rateLimit) 
        throws Throwable {
        if (!limiter.tryAcquire(rateLimit.timeout(), rateLimit.timeUnit())) {
            throw new RateLimitException("请求过于频繁");
        }
        return pjp.proceed();
    }
}
// 自定义注解
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface RateLimit {
    long timeout() default 1;
    TimeUnit timeUnit() default TimeUnit.SECONDS;
}

// Spring AbstractAutoProxyCreator 的核心逻辑
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
    return JdkDynamicAopProxy();
}
return ObjenesisCglibAopProxy();

// 不推荐（扫描范围过大）
@Pointcut("execution(* *(..))")
// 推荐（限定包路径+注解）
@Pointcut("execution(* com.yourpackage..service.*.*(..)) && " +
          "@annotation(org.springframework.transaction.annotation.Transactional)")

@Around("serviceLayer()")
public Object profile(ProceedingJoinPoint pjp) throws Throwable {
    // 错误示范：在切面内进行数据库操作
    // auditRepository.save(...); 
    // 正确做法：只做轻量级记录
    long start = System.nanoTime();
    Object result = pjp.proceed();
    long duration = System.nanoTime() - start;
    metrics.record(duration);
    return result;
}

@Aspect
@Component
public class TransactionRetryAspect {
    @Around("@annotation(retry)")
    public Object retry(ProceedingJoinPoint pjp, RetryOnConflict retry) 
        throws Throwable {
        int attempts = 0;
        do {
            try {
                return pjp.proceed();
            } catch (OptimisticLockingFailureException ex) {
                if (++attempts >= retry.maxAttempts()) throw ex;
                Thread.sleep(retry.backoff());
            }
        } while (true);
    }
}

public class OrderService {
    public void createOrder() {
        this.updateStock(); // 自调用不走代理！
    }
    @Transactional
    public void updateStock() {...}
}

((OrderService) context.getBean("orderService")).updateStock();

((OrderService) AopContext.currentProxy()).updateStock();

@DependsOn("bService") // 强制初始化顺序
@Aspect
@Component
public class AAspect {
    @Autowired
    private BService bService;
}

# application.properties
spring.aop.proxy-target-class=true # 强制使用CGLIB
logging.level.org.springframework.aop=DEBUG

@Aspect
@Component
public class AopMonitorAspect {
    @Around("within(@org.aspectj.lang.annotation.Aspect *)")
    public Object monitorAspect(ProceedingJoinPoint pjp) throws Throwable {
        String aspectName = pjp.getTarget().getClass().getSimpleName();
        Monitor.start("aop.aspect." + aspectName);
        try {
            return pjp.proceed();
        } finally {
            Monitor.end();
        }
    }
}

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>aspectj-maven-plugin</artifactId>
    <executions>
        <execution>
            <goals>
                <goal>compile</goal>
            </goals>
        </execution>
    </executions>
</plugin>