C#中間件與Redis緩存集成

在C#中，我們可以使用ASP.NET Core框架來創建一個Web應用程序，并集成中間件和Redis緩存。以下是一個簡單的示例，展示了如何在ASP.NET Core應用程序中使用中間件和Redis緩存。

1. 首先，確保已安裝以下NuGet包：

   • Microsoft.AspNetCore.Http
   • StackExchange.Redis

2. 創建一個名為RedisCacheMiddleware的新類，該類將實現中間件功能。在這個類中，我們將使用Redis緩存來存儲和檢索數據。

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，將RedisCacheMiddleware添加到中間件管道中。

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，確保在Program.cs文件中配置了Kestrel服務器。

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>();
            });
}

現在，當你運行應用程序并發送請求時，RedisCacheMiddleware將檢查Redis緩存中是否存在指定的鍵。如果存在，它將從緩存中獲取值并將其寫入響應。如果不存在，它將調用下一個中間件，并在完成后將響應體存儲在緩存中。