FileSystemWatcher如何使用

FileSystemWatcher是一个.NET类，允许开发人员监视文件系统的更改并作出相应的响应。以下是一些常见的用法示例：

1. 监视文件夹中的文件更改：

FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = @"C:\Users\JohnDoe\Documents";
watcher.Filter = "*.txt";
watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName;
watcher.Changed += OnChanged;
watcher.Created += OnChanged;
watcher.Deleted += OnChanged;
watcher.Renamed += OnRenamed;
watcher.EnableRaisingEvents = true;

private static void OnChanged(object source, FileSystemEventArgs e)
{
    Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
}

private static void OnRenamed(object source, RenamedEventArgs e)
{
    Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
}

2. 监视整个文件系统的更改：

FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = @"C:\";
watcher.IncludeSubdirectories = true;
watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName;
watcher.Changed += OnChanged;
watcher.Created += OnChanged;
watcher.Deleted += OnChanged;
watcher.Renamed += OnRenamed;
watcher.EnableRaisingEvents = true;

3. 只监视特定文件的更改：

FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = @"C:\Users\JohnDoe\Documents";
watcher.Filter = "importantFile.txt";
watcher.NotifyFilter = NotifyFilters.LastWrite;
watcher.Changed += OnChanged;
watcher.EnableRaisingEvents = true;

4. 停止监视器：

watcher.EnableRaisingEvents = false;
watcher.Dispose();

需要注意的是，FileSystemWatcher可能会触发多次事件，因此需要适当处理重复事件的情况。此外，需要注意文件系统操作可能引起的性能问题和并发问题。