C#中间件与Redis缓存集成

在C#中，我们可以使用ASP.NET Core框架来创建一个Web应用程序，并集成中间件和Redis缓存。以下是一个简单的示例，展示了如何在ASP.NET Core应用程序中使用中间件和Redis缓存。

1. 首先，确保已安装以下NuGet包：

   • Microsoft.AspNetCore.Http
   • StackExchange.Redis

2. 创建一个名为RedisCacheMiddleware的新类，该类将实现中间件功能。在这个类中，我们将使用Redis缓存来存储和检索数据。

using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using StackExchange.Redis;

public class RedisCacheMiddleware
{
    private readonly RequestDelegate _next;
    private static Lazy<ConnectionMultiplexer> lazyConnection = new Lazy<ConnectionMultiplexer>(() =>
    {
        string cacheConnection = "your_redis_connection_string";
        return ConnectionMultiplexer.Connect(cacheConnection);
    });

    public static ConnectionMultiplexer Connection => lazyConnection.Value;

    public RedisCacheMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        // Get a reference to the Redis database
        IDatabase cache = Connection.GetDatabase();

        // Get the key from the request query string
        string key = context.Request.Query["key"];

        // Check if the key exists in the cache
        if (await cache.KeyExistsAsync(key))
        {
            // If it exists, get the value from the cache and write it to the response
            string value = await cache.StringGetAsync(key);
            await context.Response.WriteAsync($"Value from cache: {value}");
        }
        else
        {
            // If it doesn't exist, call the next middleware in the pipeline
            await _next(context);

            // After the next middleware has executed, get the response body
            string responseBody = await context.Response.ReadBodyAsStringAsync();

            // Store the response body in the cache for future requests
            await cache.StringSetAsync(key, responseBody);
        }
    }
}

3. 在Startup.cs文件中，将RedisCacheMiddleware添加到中间件管道中。

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        // Add other services here
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        // Add the RedisCacheMiddleware to the middleware pipeline
        app.UseMiddleware<RedisCacheMiddleware>();

        // Add other middleware here
    }
}

4. 最后，确保在Program.cs文件中配置了Kestrel服务器。

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;

public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

现在，当你运行应用程序并发送请求时，RedisCacheMiddleware将检查Redis缓存中是否存在指定的键。如果存在，它将从缓存中获取值并将其写入响应。如果不存在，它将调用下一个中间件，并在完成后将响应体存储在缓存中。