Redis限流

在电商开发过程中，我们很多地方需要做限流，有的是从Nginx上面做限流，有的是从代码层面限流等，这里我们就是从代码层面用Redis计数器做限流，这里我们用C#语言来编写，且用特性（过滤器，拦截器）的形式拦截限流，CSRedis来作为redis的客户端包。

1-新建一个.NET CORE的WebApi项目

其中默认的Webapi如

[ApiController]

[Route("[controller]")]

public class WeatherForecastController : ControllerBase

{

private static readonly string[] Summaries = new[]

{

"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"

};

private readonly ILogger<WeatherForecastController> _logger;

public WeatherForecastController(ILogger<WeatherForecastController> logger)

{

_logger = logger;

}

[HttpGet]

public IEnumerable<WeatherForecast> Get()

{

var rng = new Random();

return Enumerable.Range(1, 5).Select(index => new WeatherForecast

{

Date = DateTime.Now.AddDays(index),

TemperatureC = rng.Next(-20, 55),

Summary = Summaries[rng.Next(Summaries.Length)]

})

.ToArray();

}

}

2-引入CSRedisCore包

使用方法可以访问地址https://github.com/ctstone/csredis

　　

3-安装启动Redis

4-新建一个特性（过滤器，拦截器），名字叫RateLimitingAttirbute

public class RateLimitingAttirbute : ActionFilterAttribute

{

private readonly int _count;

public RateLimitingAttirbute(int count)

{

_count = count;//请求次数闲置

}

public override async void OnActionExecuting(ActionExecutingContext context)

{

var userID = 0;//当我们在每个用户维度做限流，比如要限制每个用户的每个接口请求多少次，我们需要从请求头中解析用户信息，如token，获取用户的Id

var redisKey = "RedisConsts.RateLimiter";//Redis的Key

var csredis = new CSRedisClient("localhost");//链接Redis地址，这里默认本地地址

RedisHelper.Initialization(csredis);

//限流的redis的key是“RedisConsts.RateLimiter”+接口地址

var RateLimiterKey = string.Format(redisKey, $"{userID}{context.HttpContext.Request.Path.Value.Replace("/", ":")}");//获取接口地址

if (RedisHelper.Exists(RateLimiterKey))

{

string redisResult =await RedisHelper.GetAsync(RateLimiterKey);

if (int.Parse(redisResult) >= _count)//当一分钟内的请求次数大于设置的次数，则拦截

{

context.Result = new JsonResult( "请求过于频繁！");

}

else

await RedisHelper.IncrByAsync(RateLimiterKey, 1);

}

else

{

//1分钟内限制count次请求

await RedisHelper.SetAsync(RateLimiterKey, 1, new TimeSpan(0, 0, 60));

}

}

}

5-在WebApi中设置该特性

我们既可以放在某个Controller维度，也可以放在方法（Action）维度，下面的案例是放在Controller维度，下面的参数3表示一分钟内接口只能请求3次。

[ApiController]

[Route("[controller]")]

[RateLimitingAttirbute(3)]

public class WeatherForecastController : ControllerBase

{

private static readonly string[] Summaries = new[]

{

"Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"

};

private readonly ILogger<WeatherForecastController> _logger;

public WeatherForecastController(ILogger<WeatherForecastController> logger)

{

_logger = logger;

}

[HttpGet]

public IEnumerable<WeatherForecast> Get()

{

var rng = new Random();

return Enumerable.Range(1, 5).Select(index => new WeatherForecast

{

Date = DateTime.Now.AddDays(index),

TemperatureC = rng.Next(-20, 55),

Summary = Summaries[rng.Next(Summaries.Length)]

})

.ToArray();

}

}

6-运行项目，请求接口

http://localhost:53439/weatherforecast，开始是可以返回正常结果，是一个集合的值，连续请求多次，当超过3次时，会返回“请求过于频繁”

更多分享请关注我的公众号