Redis限流
作者：互联网
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”
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标签：Redis,rng,Summaries,限流,new,logger,public 来源： https://www.cnblogs.com/wangoublog/p/15330415.html