1. Guava RateLimit SmoothBurst 支持特定时间内限流，但是问题是突发时还是容易造成服务端压力
2. Guava RateLimit SmoothWarmingUp 通过设置一个预热的过程，达到速度后会趋向于平均速度限流。

import com.google.common.util.concurrent.RateLimiter;public class RateLimitToolTest {	public static void main(String[] args) throws InterruptedException {		test3();	}	// SmoothyBurst	private static void test() {		RateLimiter limiter = RateLimiter.create(5);		// limiter.acquire() 返回获取操作的耗时，以秒为单位		System.out.println(limiter.acquire());		System.out.println(limiter.acquire());		System.out.println(limiter.acquire());		System.out.println(limiter.acquire());		System.out.println(limiter.acquire());		System.out.println(limiter.acquire());	}	public static void test1() {		// 每秒允许5个请求，表示桶容量为5且每秒新增5个令牌，即每隔0.2毫秒新增一个令牌		RateLimiter limiter = RateLimiter.create(5);		// 一次性消费5个令牌		System.out.println(limiter.acquire(5));		// limiter.acquire(1)将等待差不多1秒桶中才能有令牌		System.out.println(limiter.acquire(1));		// 固定速率		System.out.println(limiter.acquire(1));		// 固定速率		System.out.println(limiter.acquire(1));		// 固定速率		System.out.println(limiter.acquire(1));	}	public static void test2() throws InterruptedException {		// 每秒允许5个请求，表示桶容量为5且每秒新增5个令牌，即每隔0.2毫秒新增一个令牌		RateLimiter limiter = RateLimiter.create(200);		long start = System.currentTimeMillis();		TimeUnit.SECONDS.sleep(2);		for (int i = 1; i <= 1000; i++) {			// 第一秒突发了10个请求			limiter.acquire(1);			if (i % 100 == 0) {				System.out.println("Spend " + (System.currentTimeMillis() - start) + " ms");			}		}	}	public static void test3() throws InterruptedException {		RateLimiter limiter = RateLimiter.create(200);		TimeUnit.SECONDS.sleep(1);		long start = System.currentTimeMillis();		for(int i =1; i < 500;i++) {			System.out.println(limiter.acquire());		}		long point = System.currentTimeMillis();		System.out.println("Spend " + (point - start));		Thread.sleep(1000L);		for(int i =1; i < 500;i++) {			System.out.println(limiter.acquire());		}		System.out.println("Spend " + (point - start));	}	// SmoothWarmingUp	public static void test4() throws InterruptedException {		RateLimiter limiter = RateLimiter.create(200,1000, TimeUnit.MILLISECONDS);		TimeUnit.SECONDS.sleep(1);		long start = System.currentTimeMillis();		for(int i =1; i < 500;i++) {			System.out.println(limiter.acquire());		}		long point = System.currentTimeMillis();		System.out.println("Spend " + (point - start));		Thread.sleep(1000L);		for(int i =1; i < 500;i++) {			System.out.println(limiter.acquire());		}		System.out.println("Spend " + (point - start));	}}复制代码