优化日志加载和清理功能，增加流式读取和定期清理日志服务

Service/LogCleanupService.cs

@@ -0,0 +1,106 @@
+using Microsoft.Extensions.Hosting;
+
+namespace Service;
+
+/// <summary>
+/// 日志清理后台服务
+/// </summary>
+public class LogCleanupService(ILogger<LogCleanupService> logger) : BackgroundService
+{
+    private readonly TimeSpan _checkInterval = TimeSpan.FromHours(24); // 每24小时检查一次
+    private const int RetentionDays = 30; // 保留30天的日志
+
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+    {
+        logger.LogInformation("日志清理服务已启动");
+
+        // 启动时立即执行一次清理
+        await CleanupOldLogsAsync();
+
+        // 定期清理
+        while (!stoppingToken.IsCancellationRequested)
+        {
+            try
+            {
+                await Task.Delay(_checkInterval, stoppingToken);
+                await CleanupOldLogsAsync();
+            }
+            catch (OperationCanceledException)
+            {
+                // 服务正在停止
+                break;
+            }
+            catch (Exception ex)
+            {
+                logger.LogError(ex, "清理日志时发生错误");
+            }
+        }
+
+        logger.LogInformation("日志清理服务已停止");
+    }
+
+    /// <summary>
+    /// 清理过期的日志文件
+    /// </summary>
+    private async Task CleanupOldLogsAsync()
+    {
+        await Task.Run(() =>
+        {
+            try
+            {
+                var logDirectory = Path.Combine(Directory.GetCurrentDirectory(), "logs");
+                if (!Directory.Exists(logDirectory))
+                {
+                    logger.LogWarning("日志目录不存在: {LogDirectory}", logDirectory);
+                    return;
+                }
+
+                var cutoffDate = DateTime.Now.AddDays(-RetentionDays);
+                var logFiles = Directory.GetFiles(logDirectory, "log-*.txt");
+                var deletedCount = 0;
+
+                foreach (var logFile in logFiles)
+                {
+                    try
+                    {
+                        var fileName = Path.GetFileNameWithoutExtension(logFile);
+                        var dateStr = fileName.Replace("log-", "");
+
+                        // 尝试解析日期 (格式: yyyyMMdd)
+                        if (DateTime.TryParseExact(dateStr, "yyyyMMdd", 
+                            System.Globalization.CultureInfo.InvariantCulture, 
+                            System.Globalization.DateTimeStyles.None, 
+                            out var logDate))
+                        {
+                            if (logDate < cutoffDate)
+                            {
+                                File.Delete(logFile);
+                                deletedCount++;
+                                logger.LogInformation("已删除过期日志文件: {LogFile} (日期: {LogDate})", 
+                                    Path.GetFileName(logFile), logDate.ToString("yyyy-MM-dd"));
+                            }
+                        }
+                    }
+                    catch (Exception ex)
+                    {
+                        logger.LogError(ex, "删除日志文件失败: {LogFile}", logFile);
+                    }
+                }
+
+                if (deletedCount > 0)
+                {
+                    logger.LogInformation("日志清理完成,共删除 {DeletedCount} 个过期日志文件(保留 {RetentionDays} 天)", 
+                        deletedCount, RetentionDays);
+                }
+                else
+                {
+                    logger.LogDebug("没有需要清理的过期日志文件");
+                }
+            }
+            catch (Exception ex)
+            {
+                logger.LogError(ex, "清理日志过程中发生错误");
+            }
+        });
+    }
+}