303 lines
12 KiB
C#
303 lines
12 KiB
C#
using LiveForum.Code.AttributeExtend;
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using LiveForum.Code.Base;
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using LiveForum.Code.Redis.Contract;
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using Microsoft.AspNetCore.Http;
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using Microsoft.AspNetCore.Mvc;
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using Microsoft.AspNetCore.Routing;
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using Microsoft.Extensions.Logging;
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using Newtonsoft.Json;
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using Newtonsoft.Json.Linq;
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using System;
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using System.IO;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace LiveForum.Code.MiddlewareExtend
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{
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/// <summary>
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/// 响应缓存中间件
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/// 通过特性标记需要缓存的Action，使用Redis进行缓存
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/// </summary>
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public class ResponseCacheMiddleware
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{
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private readonly RequestDelegate _next;
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private readonly IRedisService _redisService;
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private readonly ILogger<ResponseCacheMiddleware> _logger;
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private const string CACHE_KEY_PREFIX = "cache:api:";
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public ResponseCacheMiddleware(
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RequestDelegate next,
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IRedisService redisService,
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ILogger<ResponseCacheMiddleware> logger)
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{
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_next = next;
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_redisService = redisService;
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_logger = logger;
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}
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public async Task Invoke(HttpContext context)
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{
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// 1. 仅处理GET请求
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if (!string.Equals(context.Request.Method, "GET", StringComparison.OrdinalIgnoreCase))
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{
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await _next(context);
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return;
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}
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// 2. 获取路由信息（从路径解析）
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var path = context.Request.Path.Value ?? "";
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// 路径格式：/api/{Controller}/{Action}
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if (!path.StartsWith("/api/", StringComparison.OrdinalIgnoreCase))
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{
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await _next(context);
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return;
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}
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var pathParts = path.TrimStart('/').Split('/', StringSplitOptions.RemoveEmptyEntries);
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if (pathParts.Length < 3)
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{
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await _next(context);
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return;
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}
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var controller = pathParts[1]; // api/{controller}/...
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var action = pathParts[2]; // api/{controller}/{action}
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// 移除Controller后缀（如果有）
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if (controller.EndsWith("controller", StringComparison.OrdinalIgnoreCase))
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{
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controller = controller.Substring(0, controller.Length - 10);
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}
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// 3. 尝试获取Action的ResponseCacheAttribute特性
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var cacheAttribute = await GetResponseCacheAttributeAsync(context, controller, action);
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if (cacheAttribute == null || !cacheAttribute.Enabled)
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{
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// 没有缓存特性或已禁用，继续执行
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await _next(context);
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return;
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}
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// 4. 生成缓存Key
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var cacheKey = GenerateCacheKey(controller, action, context.Request.Query, cacheAttribute);
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try
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{
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// 5. 查询Redis缓存
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var cachedResponse = await _redisService.GetAsync(cacheKey);
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if (!string.IsNullOrEmpty(cachedResponse))
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{
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// 缓存命中，直接返回
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context.Response.ContentType = "application/json; charset=utf-8";
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context.Response.StatusCode = StatusCodes.Status200OK;
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await context.Response.WriteAsync(cachedResponse, Encoding.UTF8);
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_logger.LogInformation("[ResponseCache] 缓存命中。Key: {CacheKey}", cacheKey);
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return;
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}
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// 6. 缓存未命中，启用响应缓冲以便捕获响应
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var originalBodyStream = context.Response.Body;
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using (var responseBody = new MemoryStream())
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{
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context.Response.Body = responseBody;
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// 继续执行管道
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await _next(context);
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// 7. 读取响应内容
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responseBody.Seek(0, SeekOrigin.Begin);
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var responseBodyText = await new StreamReader(responseBody).ReadToEndAsync();
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// 将响应写回原始流
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responseBody.Seek(0, SeekOrigin.Begin);
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await responseBody.CopyToAsync(originalBodyStream);
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// 8. 检查响应状态码和业务代码
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if (context.Response.StatusCode == StatusCodes.Status200OK && !string.IsNullOrEmpty(responseBodyText))
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{
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try
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{
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// 解析JSON响应，检查Code字段
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var responseJson = JObject.Parse(responseBodyText);
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var codeValue = responseJson["code"]?.Value<int>();
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// 只有Code=0（Success）才缓存
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if (codeValue.HasValue && codeValue.Value == (int)ResponseCode.Success)
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{
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// 9. 写入Redis缓存（添加1-100秒随机数，防止缓存同时失效）
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var random = new Random();
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var randomSeconds = random.Next(1, 101); // 1-100秒随机数
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var actualDuration = cacheAttribute.Duration + randomSeconds;
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await _redisService.SetAsync(cacheKey, responseBodyText, TimeSpan.FromSeconds(actualDuration));
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_logger.LogInformation(
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"[ResponseCache] 响应已缓存。Key: {CacheKey}, 基础Duration: {Duration}秒, 随机数: {RandomSeconds}秒, 实际Duration: {ActualDuration}秒",
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cacheKey, cacheAttribute.Duration, randomSeconds, actualDuration);
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}
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else
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{
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_logger.LogInformation(
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"[ResponseCache] 响应Code不为0，不缓存。Key: {CacheKey}, Code: {Code}",
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cacheKey, codeValue);
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}
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}
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catch (JsonException ex)
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{
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_logger.LogWarning(ex, "[ResponseCache] 解析响应JSON失败，不缓存。Key: {CacheKey}", cacheKey);
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}
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}
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}
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "[ResponseCache] 缓存处理异常。Key: {CacheKey}", cacheKey);
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// 发生异常时继续正常流程
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}
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}
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/// <summary>
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/// 获取Action的ResponseCacheAttribute特性
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/// </summary>
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private async Task<ResponseCacheExtendAttribute> GetResponseCacheAttributeAsync(
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HttpContext context,
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string controller,
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string action)
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{
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try
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{
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// 通过Endpoint获取Action描述符
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var endpoint = context.GetEndpoint();
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if (endpoint?.Metadata != null)
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{
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var attribute = endpoint.Metadata
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.OfType<ResponseCacheExtendAttribute>()
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.FirstOrDefault();
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if (attribute != null)
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{
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return attribute;
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}
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}
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// 如果Endpoint中没有，尝试通过反射获取（备用方案）
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var controllerType = GetControllerType(controller);
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if (controllerType != null)
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{
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var methodInfo = controllerType.GetMethod(action,
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System.Reflection.BindingFlags.Public |
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System.Reflection.BindingFlags.Instance |
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System.Reflection.BindingFlags.IgnoreCase);
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if (methodInfo != null)
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{
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var attr = methodInfo.GetCustomAttributes(typeof(ResponseCacheExtendAttribute), false)
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.FirstOrDefault() as ResponseCacheExtendAttribute;
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if (attr != null)
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{
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return attr;
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}
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}
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}
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}
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catch (Exception ex)
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{
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_logger.LogWarning(ex, "[ResponseCache] 获取ResponseCacheAttribute特性失败。Controller: {Controller}, Action: {Action}",
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controller, action);
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}
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return null;
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}
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/// <summary>
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/// 获取Controller类型（通过反射）
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/// </summary>
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private Type GetControllerType(string controllerName)
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{
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try
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{
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// 尝试查找Controller类型
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var controllerFullName = $"LiveForum.WebApi.Controllers.{controllerName}Controller";
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var controllerType = Type.GetType(controllerFullName);
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if (controllerType == null)
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{
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// 尝试从所有已加载的程序集中查找
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foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
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{
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controllerType = assembly.GetType(controllerFullName);
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if (controllerType != null)
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break;
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}
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}
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return controllerType;
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}
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catch
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{
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return null;
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}
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}
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/// <summary>
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/// 生成缓存Key
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/// </summary>
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private string GenerateCacheKey(
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string controller,
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string action,
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IQueryCollection query,
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ResponseCacheExtendAttribute attribute)
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{
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// 如果指定了自定义前缀，使用自定义前缀
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if (!string.IsNullOrWhiteSpace(attribute.CacheKeyPrefix))
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{
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var baseKey = attribute.CacheKeyPrefix;
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// 如果有VaryByQueryKeys，追加参数
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if (attribute.VaryByQueryKeys != null && attribute.VaryByQueryKeys.Length > 0)
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{
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var paramPairs = attribute.VaryByQueryKeys
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.Where(key => query.ContainsKey(key))
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.OrderBy(key => key) // 排序确保一致性
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.Select(key => $"{key}={query[key]}")
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.ToList();
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if (paramPairs.Any())
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{
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baseKey += ":" + string.Join("&", paramPairs);
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}
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}
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return $"{CACHE_KEY_PREFIX}{baseKey}";
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}
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// 使用默认格式：cache:api:{Controller}:{Action}
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var key = $"{CACHE_KEY_PREFIX}{controller}:{action}";
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// 如果有VaryByQueryKeys，追加参数
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if (attribute.VaryByQueryKeys != null && attribute.VaryByQueryKeys.Length > 0)
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{
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var paramPairs = attribute.VaryByQueryKeys
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.Where(key => query.ContainsKey(key))
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.OrderBy(key => key) // 排序确保一致性
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.Select(key => $"{key}={query[key]}")
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.ToList();
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if (paramPairs.Any())
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{
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key += ":" + string.Join("&", paramPairs);
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}
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}
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return key;
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}
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}
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}
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