1 public class FileSystemWatcherHostedService : IHostedService
 2 {
 3     private readonly FileSystemWatcher _fileWatcher;
 4     private readonly string _path = "需要監控的目錄";
 5 
 6     public FileSystemWatcherHostedService()
 7     {
 8         _fileWatcher = new FileSystemWatcher(_path)
 9         {
10             Filter = "*.json", //監控的文件類型
11             InternalBufferSize = 65536, //緩沖區大小
12             IncludeSubdirectories = true // 包括子文件夾
13         };
14     }
15 
16     public async Task StartAsync(CancellationToken cancellationToken)
17     {
18         _fileWatcher.Changed += OnFileChanged; //文件修改事件
19         _fileWatcher.EnableRaisingEvents = true; //啟用事件
20         await Task.CompletedTask;
21     }
22 
23     private void OnFileChanged(object sender, FileSystemEventArgs e)
24     {
25         Thread.Sleep(100); //等待文件寫入完成，避免讀取到不完整的文件，或者文件被占用，可以根據實際情況調整
26         //處理文件修改事件
27     }
28 
29     public Task StopAsync(CancellationToken cancellationToken)
30     {
31         _fileWatcher.EnableRaisingEvents = false; //停止事件
32         _fileWatcher.Dispose(); //釋放資源
33 
34         return Task.CompletedTask;
35     }
36 }