在传统的web项目中，防止重复提交，通常做法是：后端生成一个唯一的提交令牌（uuid），并存储在服务端。页面提交请求携带这个提交令牌，后端验证并在第一次验证后删除该令牌，保证提交请求的唯一性。
上述的思路其实没有问题的，但是需要前后端都稍加改动，如果在业务开发完在加这个的话，改动量未免有些大了，本节的实现方案无需前端配合，纯后端处理。
思路
关于Redis 分布式锁
不了解的同学戳这里 ==> Redis分布式锁的正确实现方式
使用Redis 是为了在负载均衡部署，如果是单机的部署的项目可以使用一个线程安全的本地Cache 替代 Redis
Code
这里只贴出 AOP 类和测试类，完整代码见 ==> Gitee
@Aspect
@Component
public class RepeatSubmitAspect {
private static final Logger LOGGER = LoggerFactory.getLogger(RepeatSubmitAspect.class);
@Autowired
private RedisLock redisLock;
@Pointcut("@annotation(com.gitee.taven.aop.NoRepeatSubmit)")
public void pointCut() {}
@Around("pointCut()")
public Object before(ProceedingJoinPoint pjp) {
try {
HttpServletRequest request = RequestUtils.getRequest();
Assert.notNull(request, "request can not null");
// 此处可以用token或者JSessionId
String token = request.getHeader("Authorization");
String path = request.getServletPath();
String key = getKey(token, path);
String clientId = getClientId();
boolean isSuccess = redisLock.tryLock(key, clientId, 10);
LOGGER.info("tryLock key = [{}], clientId = [{}]", key, clientId);
if (isSuccess) {
LOGGER.info("tryLock success, key = [{}], clientId = [{}]", key, clientId);
// 获取锁成功, 执行进程
Object result = pjp.proceed();
// 解锁
redisLock.releaseLock(key, clientId);
LOGGER.info("releaseLock success, key = [{}], clientId = [{}]", key, clientId);
return result;
} else {
// 获取锁失败，认为是重复提交的请求
LOGGER.info("tryLock fail, key = [{}]", key);
return new ApiResult(200, "重复请求，请稍后再试", null);
}
} catch (Throwable throwable) {
throwable.printStackTrace();
}
return new ApiResult(500, "系统异常", null);
}
private String getKey(String token, String path) {
return token + path;
}
private String getClientId() {
return UUID.randomUUID().toString();
}
}
多线程测试
测试代码如下，模拟十个请求并发同时提交
@Component
public class RunTest implements ApplicationRunner {
private static final Logger LOGGER = LoggerFactory.getLogger(RunTest.class);
@Autowired
private RestTemplate restTemplate;
@Override
public void run(ApplicationArguments args) throws Exception {
System.out.println("执行多线程测试");
String url="http://localhost:8000/submit";
CountDownLatch countDownLatch = new CountDownLatch(1);
ExecutorService executorService = Executors.newFixedThreadPool(10);
for(int i=0; i<10; i++){
String userId = "userId" + i;
HttpEntity request = buildRequest(userId);
executorService.submit(() -> {
try {
countDownLatch.await();
System.out.println("Thread:"+Thread.currentThread().getName()+", time:"+System.currentTimeMillis());
ResponseEntity<String> response = restTemplate.postForEntity(url, request, String.class);
System.out.println("Thread:"+Thread.currentThread().getName() + "," + response.getBody());
} catch (InterruptedException e) {
e.printStackTrace();
}
});
}
countDownLatch.countDown();
}
private HttpEntity buildRequest(String userId) {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
headers.set("Authorization", "yourToken");
Map<String, Object> body = new HashMap<>();
body.put("userId", userId);
return new HttpEntity<>(body, headers);
}
}
成功防止重复提交，控制台日志如下，可以看到十个线程的启动时间几乎同时发起，只有一个请求提交成功了
本节demo
戳这里 ==> Gitee
build项目之后，启动本地redis，运行项目自动执行测试方法
