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在上一篇文章中,我们详细的介绍了随着下单流量逐渐上升,为了降低数据库的访问压力,通过请求唯一ID
+Redis
分布式锁来防止接口重复提交,流程图如下!
每次提交的时候,需要先调用后端服务获取请求唯一ID
,然后才能提交。
对于这样的流程,不少的同学可能会感觉到非常鸡肋,尤其是单元测试,需要每次先获取submitToken
值,然后才能提交!
能不能不用这么麻烦,直接服务端通过一些规则组合,生成本次请求唯一ID呢?
答案是可以的!
今天我们就一起来看看,如何通过服务端来完成请求唯一 ID 的生成?
我们先来看一张图,这张图就是本次方案的核心流程图。
实现的逻辑,流程如下:
1.用户点击提交按钮,服务端接受到请求后,通过规则计算出本次请求唯一ID值
2.使用redis
的分布式锁服务,对请求 ID 在限定的时间内尝试进行加锁,如果加锁成功,继续后续流程;如果加锁失败,说明服务正在处理,请勿重复提交
3.最后一步,如果加锁成功后,需要将锁手动释放掉,以免再次请求时,提示同样的信息
引入缓存服务后,防止重复提交的大体思路如上,实践代码如下!
本次项目是基于SpringBoot版本
进行构建,添加相关的redis
依赖环境如下:
<!-- 引入springboot --> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.0.RELEASE</version> </parent> ...... <!-- Redis相关依赖包,采用jedis作为客户端 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId> <exclusions> <exclusion> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> </exclusion> <exclusion> <artifactId>lettuce-core</artifactId> <groupId>io.lettuce</groupId> </exclusion> </exclusions> </dependency> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-pool2</artifactId> </dependency>
特别注意:由于每个项目环境不一样,具体的依赖包需要和工程版本号匹配!
在全局配置application.properties
文件中,添加Redis
相关服务配置如下
# Redis数据库索引(默认为0) spring.redis.database=1 # Redis服务器地址 spring.redis.host=127.0.0.1 # Redis服务器连接端口 spring.redis.port=6379 # Redis服务器连接密码(默认为空) spring.redis.password= # Redis服务器连接超时配置 spring.redis.timeout=1000 # 连接池配置 spring.redis.jedis.pool.max-active=8 spring.redis.jedis.pool.max-wait=1000 spring.redis.jedis.pool.max-idle=8 spring.redis.jedis.pool.min-idle=0 spring.redis.jedis.pool.time-between-eviction-runs=100
在使用redis
之前,请确保redis
服务器是启动状态,并且能正常访问!
首先创建一个@SubmitLimit注解,通过这个注解来进行方法代理拦截!
@Retention(RetentionPolicy.RUNTIME) @Target({ElementType.METHOD}) @Documented public @interface SubmitLimit { /** * 指定时间内不可重复提交(仅相对上一次发起请求时间差),单位毫秒 * @return */ int waitTime() default 1000; /** * 指定请求头部key,可以组合生成签名 * @return */ String[] customerHeaders() default {}; /** * 自定义重复提交提示语 * @return */ String customerTipMsg() default ""; }
编写方法代理服务,增加防止重复提交的验证,实现了逻辑如下!
@Order(1) @Aspect @Component public class SubmitLimitAspect { private static final Logger LOGGER = LoggerFactory.getLogger(SubmitLimitAspect.class); /** * redis分割符 */ private static final String REDIS_SEPARATOR = ":"; /** * 默认锁对应的值 */ private static final String DEFAULT_LOCK_VALUE = "DEFAULT_SUBMIT_LOCK_VALUE"; /** * 默认重复提交提示语 */ private static final String DEFAULT_TIP_MSG = "服务正在处理,请勿重复提交!"; @Value("${spring.application.name}") private String applicationName; @Autowired private RedisLockService redisLockService; /** * 方法调用环绕拦截 */ @Around(value = "@annotation(com.example.submittoken.config.annotation.SubmitLimit)") public Object doAround(ProceedingJoinPoint joinPoint){ HttpServletRequest request = getHttpServletRequest(); if(Objects.isNull(request)){ return ResResult.getSysError("请求参数不能为空!"); } //获取注解配置的参数 SubmitLimit submitLimit = getSubmitLimit(joinPoint); //组合生成key,通过key实现加锁和解锁 String lockKey = buildSubmitLimitKey(joinPoint, request, submitLimit.customerHeaders()); //尝试在指定的时间内加锁 boolean lock = redisLockService.tryLock(lockKey, DEFAULT_LOCK_VALUE, Duration.ofMillis(submitLimit.waitTime())); if(!lock){ String tipMsg = StringUtils.isEmpty(submitLimit.customerTipMsg()) ? DEFAULT_TIP_MSG : submitLimit.customerTipMsg(); return ResResult.getSysError(tipMsg); } try { //继续执行后续流程 return execute(joinPoint); } finally { //执行完毕之后,手动将锁释放 redisLockService.releaseLock(lockKey, DEFAULT_LOCK_VALUE); } } /** * 执行任务 * @param joinPoint * @return */ private Object execute(ProceedingJoinPoint joinPoint){ try { return joinPoint.proceed(); } catch (CommonException e) { return ResResult.getSysError(e.getMessage()); } catch (Throwable e) { LOGGER.error("业务处理发生异常,错误信息:",e); return ResResult.getSysError(ResResultEnum.DEFAULT_ERROR_MESSAGE); } } /** * 获取请求对象 * @return */ private HttpServletRequest getHttpServletRequest(){ RequestAttributes ra = RequestContextHolder.getRequestAttributes(); ServletRequestAttributes sra = (ServletRequestAttributes)ra; HttpServletRequest request = sra.getRequest(); return request; } /** * 获取注解值 * @param joinPoint * @return */ private SubmitLimit getSubmitLimit(JoinPoint joinPoint){ MethodSignature methodSignature = (MethodSignature) joinPoint.getSignature(); Method method = methodSignature.getMethod(); SubmitLimit submitLimit = method.getAnnotation(SubmitLimit.class); return submitLimit; } /** * 组合生成lockKey * 生成规则:项目名+接口名+方法名+请求参数签名(对请求头部参数+请求body参数,取SHA1值) * @param joinPoint * @param request * @param customerHeaders * @return */ private String buildSubmitLimitKey(JoinPoint joinPoint, HttpServletRequest request, String[] customerHeaders){ //请求参数=请求头部+请求body String requestHeader = getRequestHeader(request, customerHeaders); String requestBody = getRequestBody(joinPoint.getArgs()); String requestParamSign = DigestUtils.sha1Hex(requestHeader + requestBody); String submitLimitKey = new StringBuilder() .append(applicationName) .append(REDIS_SEPARATOR) .append(joinPoint.getSignature().getDeclaringType().getSimpleName()) .append(REDIS_SEPARATOR) .append(joinPoint.getSignature().getName()) .append(REDIS_SEPARATOR) .append(requestParamSign) .toString(); return submitLimitKey; } /** * 获取指定请求头部参数 * @param request * @param customerHeaders * @return */ private String getRequestHeader(HttpServletRequest request, String[] customerHeaders){ if (Objects.isNull(customerHeaders)) { return ""; } StringBuilder sb = new StringBuilder(); for (String headerKey : customerHeaders) { sb.append(request.getHeader(headerKey)); } return sb.toString(); } /** * 获取请求body参数 * @param args * @return */ private String getRequestBody(Object[] args){ if (Objects.isNull(args)) { return ""; } StringBuilder sb = new StringBuilder(); for (Object arg : args) { if (arg instanceof HttpServletRequest || arg instanceof HttpServletResponse || arg instanceof MultipartFile || arg instanceof BindResult || arg instanceof MultipartFile[] || arg instanceof ModelMap || arg instanceof Model || arg instanceof ExtendedServletRequestDataBinder || arg instanceof byte[]) { continue; } sb.append(JacksonUtils.toJson(arg)); } return sb.toString(); } }
部分校验逻辑用到了redis
分布式锁,具体实现逻辑如下:
/** * redis分布式锁服务类 * 采用LUA脚本实现,保证加锁、解锁操作原子性 * */ @Component public class RedisLockService { /** * 分布式锁过期时间,单位秒 */ private static final Long DEFAULT_LOCK_EXPIRE_TIME = 60L; @Autowired private StringRedisTemplate stringRedisTemplate; /** * 尝试在指定时间内加锁 * @param key * @param value * @param timeout 锁等待时间 * @return */ public boolean tryLock(String key,String value, Duration timeout){ long waitMills = timeout.toMillis(); long currentTimeMillis = System.currentTimeMillis(); do { boolean lock = lock(key, value, DEFAULT_LOCK_EXPIRE_TIME); if (lock) { return true; } try { Thread.sleep(1L); } catch (InterruptedException e) { Thread.interrupted(); } } while (System.currentTimeMillis() < currentTimeMillis + waitMills); return false; } /** * 直接加锁 * @param key * @param value * @param expire * @return */ public boolean lock(String key,String value, Long expire){ String luaScript = "if redis.call('setnx', KEYS[1], ARGV[1]) == 1 then return redis.call('expire', KEYS[1], ARGV[2]) else return 0 end"; RedisScript<Long> redisScript = new DefaultRedisScript<>(luaScript, Long.class); Long result = stringRedisTemplate.execute(redisScript, Collections.singletonList(key), value, String.valueOf(expire)); return result.equals(Long.valueOf(1)); } /** * 释放锁 * @param key * @param value * @return */ public boolean releaseLock(String key,String value){ String luaScript = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end"; RedisScript<Long> redisScript = new DefaultRedisScript<>(luaScript, Long.class); Long result = stringRedisTemplate.execute(redisScript, Collections.singletonList(key),value); return result.equals(Long.valueOf(1)); } }
部分代码使用到了序列化相关类JacksonUtils
,源码如下:
public class JacksonUtils { private static final Logger LOGGER = LoggerFactory.getLogger(JacksonUtils.class); private static final ObjectMapper objectMapper = new ObjectMapper(); static { // 对象的所有字段全部列入 objectMapper.setSerializationInclusion(JsonInclude.Include.ALWAYS); // 忽略未知的字段 objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); // 读取不认识的枚举时,当null值处理 objectMapper.configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL, true); // 序列化忽略未知属性 objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false); //忽略字段大小写 objectMapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES, true); objectMapper.configure(JsonParser.Feature.AUTO_CLOSE_SOURCE, true); SimpleModule module = new SimpleModule(); module.addSerializer(Long.class, ToStringSerializer.instance); module.addSerializer(Long.TYPE, ToStringSerializer.instance); objectMapper.registerModule(module); } public static String toJson(Object object) { if (object == null) { return null; } try { return objectMapper.writeValueAsString(object); } catch (Exception e) { LOGGER.error("序列化失败",e); } return null; } public static <T> T fromJson(String json, Class<T> classOfT) { if (json == null) { return null; } try { return objectMapper.readValue(json, classOfT); } catch (Exception e) { LOGGER.error("反序列化失败",e); } return null; } public static <T> T fromJson(String json, Type typeOfT) { if (json == null) { return null; } try { return objectMapper.readValue(json, objectMapper.constructType(typeOfT)); } catch (Exception e) { LOGGER.error("反序列化失败",e); } return null; } }
@RestController @RequestMapping("order") public class OrderController { @Autowired private OrderService orderService; /** * 下单,指定请求头部参与请求唯一值计算 * @param request * @return */ @SubmitLimit(customerHeaders = {"appId", "token"}, customerTipMsg = "正在加紧为您处理,请勿重复下单!") @PostMapping(value = "confirm") public ResResult confirmOrder(@RequestBody OrderConfirmRequest request){ //调用订单下单相关逻辑 orderService.confirm(request); return ResResult.getSuccess(); } }
其中最关键的一个步就是将唯一请求 ID 的生成,放在服务端通过组合来实现,在保证防止接口重复提交的效果同时,也可以显著的降低接口测试复杂度!
本次方案相比于上一个方案,最大的改进点在于:将接口请求唯一 ID 的生成逻辑,放在服务端通过规则组合来实现,不需要前端提交接口的时候强制带上这个参数,在满足防止接口重复提交的要求同时,又能减少前端和测试提交接口的复杂度!
需要特别注意的是:使用redis
的分布式锁,推荐单机环境,如果redis
是集群环境,可能会导致锁短暂无效!
解决方式一:https://blog.csdn.net/weixin_47316183/article/details/130180165?spm=1001.2014.3001.5502
解决方式二:https://blog.csdn.net/weixin_47316183/article/details/130180299?spm=1001.2014.3001.5502
解决方式三:https://blog.csdn.net/weixin_47316183/article/details/130180446?spm=1001.2014.3001.5502
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