springboot-aop-redis-lua 实现的分布式限流方案

1.自定义限流注解

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Limit {/*** 名字*/String name() default "";/*** key*/String key() default "";/*** Key的前缀*/String prefix() default "";/*** 给定的时间范围 单位(秒)*/int period();/*** 一定时间内最多访问次数*/int count();/*** 限流的类型(用户自定义key 或者 请求ip)*/LimitType limitType() default LimitType.CUSTOMER;
}

2. 限流类型

public enum LimitType {/*** 自定义key*/CUSTOMER,/*** 请求者IP*/IP;
}

 3.redis配置

@Configuration
public class RedisLimiterHelper {@Beanpublic RedisTemplate<String, Serializable> limitRedisTemplate(LettuceConnectionFactory redisConnectionFactory) {RedisTemplate<String, Serializable> template = new RedisTemplate<>();template.setKeySerializer(new StringRedisSerializer());template.setValueSerializer(new GenericJackson2JsonRedisSerializer());template.setConnectionFactory(redisConnectionFactory);return template;}
}

4. 限流切面实现

/*** @author* @description 限流切面实现* @date 2020/4/8 13:04*/
@Aspect
@Configuration
public class LimitInterceptor {private static final Logger logger = LoggerFactory.getLogger(LimitInterceptor.class);private static final String UNKNOWN = "unknown";private final RedisTemplate<String, Serializable> limitRedisTemplate;@Autowiredpublic LimitInterceptor(RedisTemplate<String, Serializable> limitRedisTemplate) {this.limitRedisTemplate = limitRedisTemplate;}/*** @param pjp* @authofuor * @description 切面* @date 2020/4/8 13:04*/@Around("execution(public * *(..)) && @annotation(com..limit.api.Limit)")public Object interceptor(ProceedingJoinPoint pjp) {MethodSignature signature = (MethodSignature) pjp.getSignature();Method method = signature.getMethod();Limit limitAnnotation = method.getAnnotation(Limit.class);LimitType limitType = limitAnnotation.limitType();String name = limitAnnotation.name();String key;int limitPeriod = limitAnnotation.period();int limitCount = limitAnnotation.count();/*** 根据限流类型获取不同的key ,如果不传我们会以方法名作为key*/switch (limitType) {case IP:key = getIpAddress();break;case CUSTOMER:key = limitAnnotation.key();break;default:key = StringUtils.upperCase(method.getName());}ImmutableList<String> keys = ImmutableList.of(StringUtils.join(limitAnnotation.prefix(), key));try {String luaScript = buildLuaScript();RedisScript<Number> redisScript = new DefaultRedisScript<>(luaScript, Number.class);Number count = limitRedisTemplate.execute(redisScript, keys, limitCount, limitPeriod);logger.info("Access try count is {} for name={} and key = {}", count, name, key);if (count != null && count.intValue() <= limitCount) {return pjp.proceed();} else {throw new RuntimeException("You have been dragged into the blacklist");}} catch (Throwable e) {if (e instanceof RuntimeException) {throw new RuntimeException(e.getLocalizedMessage());}throw new RuntimeException("server exception");}}/*** @author xiaofu* @description 编写 redis Lua 限流脚本*/public String buildLuaScript() {StringBuilder lua = new StringBuilder();lua.append("local c");lua.append("\nc = redis.call('get',KEYS[1])");// 调用不超过最大值，则直接返回lua.append("\nif c and tonumber(c) > tonumber(ARGV[1]) then");lua.append("\nreturn c;");lua.append("\nend");// 执行计算器自加lua.append("\nc = redis.call('incr',KEYS[1])");lua.append("\nif tonumber(c) == 1 then");// 从第一次调用开始限流，设置对应键值的过期lua.append("\nredis.call('expire',KEYS[1],ARGV[2])");lua.append("\nend");lua.append("\nreturn c;");logger.info("====="+lua.toString());return lua.toString();}/*** @description 获取id地址*/public String getIpAddress() {HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();String ip = request.getHeader("x-forwarded-for");if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {ip = request.getHeader("Proxy-Client-IP");}if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {ip = request.getHeader("WL-Proxy-Client-IP");}if (ip == null || ip.length() == 0 || UNKNOWN.equalsIgnoreCase(ip)) {ip = request.getRemoteAddr();}return ip;}
}

上述Lua脚本解释：jdk8在书写脚本的时候需要使用字符串拼接的方式，jdk17以及以后可以使用代码片段书写

local c    //局部变量
c = redis.call('get',KEYS[1])  //从redis获取key执行的次数
if c and tonumber(c) > tonumber(ARGV[1]) then   //获取的key执行的次数是否大于允许的最大值，如果是直接返回，拒绝访问
return c;
end
c = redis.call('incr',KEYS[1])   //key对应的value增加1
if tonumber(c) == 1 then  //当前的key是否是第一次
redis.call('expire',KEYS[1],ARGV[2]) //对key设置过期时间
end
return c;

5.测试例子

package com.xiaofu.limit.controller;import com.xiaofu.limit.api.Limit;
import com.xiaofu.limit.enmu.LimitType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.concurrent.atomic.AtomicInteger;@RestController
public class LimiterController {private static final AtomicInteger ATOMIC_INTEGER_1 = new AtomicInteger();private static final AtomicInteger ATOMIC_INTEGER_2 = new AtomicInteger();private static final AtomicInteger ATOMIC_INTEGER_3 = new AtomicInteger();@Limit(name = "1111", key = "limitTest", period = 10, count = 3)@GetMapping("/limitTest1")public int testLimiter1() {return ATOMIC_INTEGER_1.incrementAndGet();}@Limit(key = "customer_limit_test", period = 10, count = 3, limitType = LimitType.CUSTOMER)@GetMapping("/limitTest2")public int testLimiter2() {return ATOMIC_INTEGER_2.incrementAndGet();}@Limit(key = "ip_limit_test", period = 10, count = 3, limitType = LimitType.IP)@GetMapping("/limitTest3")public int testLimiter3() {return ATOMIC_INTEGER_3.incrementAndGet();}}