使用场景:在分布式系统中需要对一些方法进行分布式锁的添加,保证原子性。但是加锁的代码基本是重复的,每个方法都写一遍这个加锁代码,这显然不合适,所以这里才有了自定义一个注解和Aspect 切面编程实现加锁。
自定义注解类:
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface OperateLock {
String value() default "orderNo";
}
切面类:
@Aspect
@Component
public class LockControllerAspect {
private static final Logger logger = LoggerFactory.getLogger(LockControllerAspect.class);
@Autowired
private ConcurrentLockService concurrentLockService;
@Pointcut("execution(* com.xinchengbaina.retail.middleend.api.controller.*.*(..))")
public void operate() {
}
@Around("operate()")
public Object aroundOperate(ProceedingJoinPoint joinPoint) throws Throwable {
Signature signature = joinPoint.getSignature();
MethodSignature methodSignature = (MethodSignature) signature;
Method method = methodSignature.getMethod();
Object result = null;
//是否加锁
boolean noLock = true;
OperateLock operateLock = method.getAnnotation(OperateLock.class);
if (operateLock != null) {
OrderRequest operator = null;
for (Object o : joinPoint.getArgs()) {
if (o instanceof OrderRequest) {
operator = (OrderRequest) o;
break;
}
}
if (operator != null) {
Long orderNo = operator.getOrderNo();
if (!concurrentLockService.lock(orderNo)) {
throw new BusinessException(OrderExceptionEnum.OPERATE_BUSY.getCode());
}
try {
noLock = false;
result = joinPoint.proceed();
} catch (Exception e) {
throw e;
} finally {
concurrentLockService.unlock(orderNo);
}
}
}
if (noLock) {
result = joinPoint.proceed();
}
return result;
}
}