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; }
- 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 { @Bean public 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; } }
- 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; @Autowired public 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(); } }