Java中使用RedisTemplate+Lua脚本实现分布式Redis令牌桶限流

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import java.util.Collections;
 
// 使用Lua脚本在Redis中实现令牌桶限流
public class LuaTokenBucketRateLimiter {
 
    private final StringRedisTemplate redisTemplate;
    private final DefaultRedisScript<Long> luaScript;
 
    public LuaTokenBucketRateLimiter(StringRedisTemplate redisTemplate) {
        this.redisTemplate = redisTemplate;
 
        // Lua脚本用于令牌桶限流
        String luaScriptSource = 
            "local key = KEYS[1] " +
            "local limit = tonumber(ARGV[1]) " +
            "local current = tonumber(redis.call('get', key) or '0') " +
            "if current + 1 > limit then return 0 else " +
            "   redis.call('INCRBY', key, '1') " +
            "   redis.call('EXPIRE', key, '10') " +
            "   return 1 " +
            "end";
 
        this.luaScript = new DefaultRedisScript<>();
        luaScript.setScriptText(luaScriptSource);
        luaScript.setResultType(Long.class);
    }
 
    public boolean isAllowed(String key, int limit) {
        Long isAllowed = redisTemplate.execute(luaScript, Collections.singletonList(key), Collections.singletonList(String.valueOf(limit)));
        return isAllowed == null ? false : isAllowed.intValue() == 1;
    }
}

这段代码展示了如何使用Lua脚本和StringRedisTemplate来实现一个简单的令牌桶限流器。isAllowed方法会检查当前请求是否超过了限制，如果没有则允许通过并更新令牌桶状态。这个例子简单明了，并且可以作为在实际应用中实现更复杂限流逻辑的基础。