用FileSystemWatcher监视文件变化

public class Watcher
{

public static void Main()
{
Run();

}

[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public static void Run()
{
string[] args = System.Environment.GetCommandLineArgs();

// If a directory is not specified, exit program.
if(args.Length != 2)
{
// Display the proper way to call the program.
Console.WriteLine("Usage: Watcher.exe (directory)");
return;
}

// Create a new FileSystemWatcher and set its properties.
FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = args[1];
/**//* Watch for changes in LastAccess and LastWrite times, and
the renaming of files or directories. */
watcher.NotifyFilter = NotifyFilters.LastAccess 　 NotifyFilters.LastWrite
　 NotifyFilters.FileName 　 NotifyFilters.DirectoryName;
// Only watch text files.
watcher.Filter = "*.txt";

// Add event handlers.
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.Deleted += new FileSystemEventHandler(OnChanged);
watcher.Renamed += new RenamedEventHandler(OnRenamed);

// Begin watching.
watcher.EnableRaisingEvents = true;

// Wait for the user to quit the program.
Console.WriteLine("Press 'q' to quit the sample.");
while(Console.Read()!='q');
}

// Define the event handlers.
private static void OnChanged(object source, FileSystemEventArgs e)
{
// Specify what is done when a file is changed, created, or deleted.
Console.WriteLine("File: " + e.FullPath + " " + e.ChangeType);
}

private static void OnRenamed(object source, RenamedEventArgs e)
{
// Specify what is done when a file is renamed.
Console.WriteLine("File: {0} renamed to {1}", e.OldFullPath, e.FullPath);
}
}
需要注意的两点：
1. 必须设置watcher.EnableRaisingEvents为true才可以开始监视
2. 使用watcher.WaitForChanged(WatcherChangeTypes.Changed,1000)方法时必须指定第二个参数timeout，如果不指定，则程序会一直在等待。