封装RateLimiter 令牌桶算法

自定义注解封装RateLimiter.实例:

@RequestMapping("/myOrder")

@ExtRateLimiter(value = 10.0, timeOut = 500)

public String myOrder() throws InterruptedException {

System.out.println("myOrder");

return "SUCCESS";

}

自定义注解

@Target(value = ElementType.METHOD)

@Retention(RetentionPolicy.RUNTIME)

public @interface ExtRateLimiter {

double value();

long timeOut();

}

编写AOP

@Aspect

@Component

public class RateLimiterAop {

// 存放接口是否已经存在

private static ConcurrentHashMap<String, RateLimiter> rateLimiterMap = new ConcurrentHashMap<String, RateLimiter>();

@Pointcut("execution(public * com.it.api.*.*(..))")

public void rlAop() {

}

@Around("rlAop()")

public Object doBefore(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {

MethodSignature signature = (MethodSignature) proceedingJoinPoint.getSignature();

// 使用Java反射技术获取方法上是否有@ExtRateLimiter注解类

ExtRateLimiter extRateLimiter = signature.getMethod().getDeclaredAnnotation(ExtRateLimiter.class);

if (extRateLimiter == null) {

// 正常执行方法

Object proceed = proceedingJoinPoint.proceed();

return proceed;

}

// ############获取注解上的参数 配置固定速率 ###############

// 获取配置的速率

double value = extRateLimiter.value();

// 获取等待令牌等待时间

long timeOut = extRateLimiter.timeOut();

RateLimiter rateLimiter = getRateLimiter(value, timeOut);

// 判断令牌桶获取token 是否超时

boolean tryAcquire = rateLimiter.tryAcquire(timeOut, TimeUnit.MILLISECONDS);

if (!tryAcquire) {

serviceDowng();

return null;

}

// 获取到令牌,直接执行..

Object proceed = proceedingJoinPoint.proceed();

return proceed;

}

// 获取RateLimiter对象

private RateLimiter getRateLimiter(double value, long timeOut) {

// 获取当前URL

ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();

HttpServletRequest request = attributes.getRequest();

String requestURI = request.getRequestURI();

RateLimiter rateLimiter = null;

if (!rateLimiterMap.containsKey(requestURI)) {

// 开启令牌通限流

rateLimiter = RateLimiter.create(value); // 独立线程

rateLimiterMap.put(requestURI, rateLimiter);

} else {

rateLimiter = rateLimiterMap.get(requestURI);

}

return rateLimiter;

}

// 服务降级

private void serviceDowng() throws IOException {

// 执行服务降级处理

System.out.println("执行降级方法,亲,服务器忙！请稍后重试!");

ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();

HttpServletResponse response = attributes.getResponse();

response.setHeader("Content-type", "text/html;charset=UTF-8");

PrintWriter writer = response.getWriter();

try {

writer.println("执行降级方法,亲,服务器忙！请稍后重试!");

} catch (Exception e) {

} finally {

writer.close();

}

}

public static void main(String[] args) {

// 使用Java反射技术获取方法上是否有@ExtRateLimiter注解类

ExtRateLimiter extRateLimiter = IndexController.class.getClass().getAnnotation(ExtRateLimiter.class);

System.out.println(extRateLimiter);

}

}

运行效果

@RequestMapping("/myOrder")

@ExtRateLimiter(value = 10.0, timeOut = 500)

public String myOrder() throws InterruptedException {

System.out.println("myOrder");

return "SUCCESS";

}