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http接口幂等性

news 2025/9/8 8:22:42

实现 HTTP 接口的幂等性是确保多次相同请求产生相同结果的重要设计原则，尤其在网络不稳定或分布式系统中非常关键。以下是几种常见的实现方式：

1. 基于幂等性令牌（Token）的实现

适合支付、订单创建等场景，步骤如下：

客户端获取令牌
客户端携带令牌请求接口
服务端验证并消费令牌

@Service
public class IdempotentService {// 实际项目中使用Redis等分布式缓存private final Set<String> tokenStore = ConcurrentHashMap.newKeySet();// 生成令牌public String generateToken() {String token = UUID.randomUUID().toString();tokenStore.add(token);return token;}// 验证令牌public boolean validateToken(String token) {return tokenStore.remove(token); // 原子操作，确保唯一消费}
}@RestController
@RequestMapping("/orders")
public class OrderController {@Autowiredprivate IdempotentService idempotentService;@Autowiredprivate OrderService orderService;@PostMappingpublic ResponseEntity<?> createOrder(@RequestHeader("Idempotency-Token") String token,@RequestBody OrderRequest request) {// 验证令牌if (!idempotentService.validateToken(token)) {return ResponseEntity.ok("重复请求，已处理");}// 处理订单逻辑OrderResult result = orderService.createOrder(request);return ResponseEntity.ok(result);}
}

2. 基于数据库唯一约束

通过数据库唯一索引确保重复数据无法插入：

// 实体类
@Entity
@Table(uniqueConstraints = {@UniqueConstraint(columnNames = {"order_no"}) // 订单号唯一约束
})
public class Order {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;private String orderNo;// 其他字段...
}// 服务层
@Service
public class OrderService {@Autowiredprivate OrderRepository orderRepository;@Transactionalpublic Order createOrder(OrderRequest request) {String orderNo = generateOrderNo();Order order = new Order();order.setOrderNo(orderNo);// 设置其他字段...try {return orderRepository.save(order);} catch (DataIntegrityViolationException e) {// 捕获唯一约束异常，视为重复请求log.warn("订单已存在: {}", orderNo);return orderRepository.findByOrderNo(orderNo).orElseThrow();}}
}

3. 基于 Redis 的分布式锁

适合分布式系统中的幂等性控制：

@Service
public class RedisIdempotentService {@Autowiredprivate StringRedisTemplate redisTemplate;private static final String IDEMPOTENT_KEY_PREFIX = "idempotent:";private static final long EXPIRATION_TIME = 30L; // 30秒过期public boolean checkAndLock(String key) {String redisKey = IDEMPOTENT_KEY_PREFIX + key;// SET NX 命令：不存在则设置，返回truereturn Boolean.TRUE.equals(redisTemplate.opsForValue().setIfAbsent(redisKey, "1", EXPIRATION_TIME, TimeUnit.SECONDS));}public void releaseLock(String key) {String redisKey = IDEMPOTENT_KEY_PREFIX + key;redisTemplate.delete(redisKey);}
}// 控制器中使用
@PostMapping("/pay")
public ResponseEntity<?> pay(@RequestParam String orderId) {if (!redisIdempotentService.checkAndLock(orderId)) {return ResponseEntity.ok("支付请求已处理");}try {// 处理支付逻辑paymentService.processPayment(orderId);return ResponseEntity.ok("支付成功");} finally {redisIdempotentService.releaseLock(orderId);}
}

4. 基于 Spring AOP 的幂等性注解

通过自定义注解简化幂等性控制：

// 自定义注解
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Idempotent {// 幂等键的参数索引，默认取第一个参数int keyIndex() default 0;
}// AOP切面
@Aspect
@Component
public class IdempotentAspect {@Autowiredprivate RedisIdempotentService redisService;@Around("@annotation(idempotent) && args(.., request)")public Object around(ProceedingJoinPoint joinPoint, Idempotent idempotent, HttpServletRequest request) throws Throwable {// 获取幂等键（此处从请求头获取）String key = request.getHeader("Idempotency-Key");if (StringUtils.isEmpty(key)) {return ResponseEntity.badRequest().body("缺少幂等键");}if (!redisService.checkAndLock(key)) {return ResponseEntity.ok("重复请求");}try {return joinPoint.proceed();} finally {// 非必须，根据业务设置过期时间自动释放// redisService.releaseLock(key);}}
}// 接口使用
@PostMapping("/transfer")
@Idempotent
public ResponseEntity<?> transferMoney(@RequestBody TransferRequest request) {// 处理转账逻辑return ResponseEntity.ok(transferService.transfer(request));
}