Using FileSystemWatcher to Monitor Multiple Directories

In a previous example, I showed how to use the FileSystemWatcher class to monitor a directory. But there are times when we need to monitor multiple directories and if any changes are available, invoke a given method.

We can do that by using the following method. First create a class. We’ll call this class Watcher.

   1: public class Watcher
   2:     {     
   3:         public string Directory { get; set; }
   4:         public string  Filter { get; set; }   6:  
   5:  
   6:         private Delegate _changeMethod;
   7:  
   8:         public Delegate ChangeMethod
   9:         {
  10:             get { return _changeMethod; }
  11:             set { _changeMethod = value; }
  12:         }
  13:         
  14:         FileSystemWatcher fileSystemWatcher = new FileSystemWatcher();
  15:  
  16:         public Watcher(string directory, string filter, Delegate invokeMethod)
  17:         {
  18:             this._changeMethod = invokeMethod;
  19:             this.Directory = directory;
  20:             this.Filter = filter;	
  21:         }  
  22:  
  23:         public void StartWatch()
  24:         {   
  25:             fileSystemWatcher.Filter = this.Filter;
  26:             fileSystemWatcher.Path = this.Directory;
  27:             fileSystemWatcher.EnableRaisingEvents = true;
  28:  
  29:             fileSystemWatcher.Changed += 
                    new FileSystemEventHandler(fileSystemWatcher_Changed);
  30:         }
  31:  
  32:         void fileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
  33:         {
  34:             if (_changeMethod != null)
  35:             {
  36:                 _changeMethod.DynamicInvoke(sender, e);
  37:             }
  38:         }
  39:     }

And we can use it to monitor multiple directories as shown below (for this example, I have used a console application and I am only considering the change event):

   1: class Program
   2:     {
   3:         delegate void invokeMethodDelegate(object sender, FileSystemEventArgs e);
   4:  
   5:         static void Main(string[] args)
   6:         {             
   7:             invokeMethodDelegate mymethod = new invokeMethodDelegate(InvokeMethod);
   8:             Watcher w1 = new Watcher(@"C:\Directory1", "*.*", mymethod);
   9:             w1.StartWatch();
  10:  
  11:             Watcher w2 = new Watcher(@"D:\Directory2", "*.*", mymethod);
  12:             w2.StartWatch();
  13:  
  14:             string zRetVal = Console.ReadLine();           
  15:         }
  16:  
  17:         static  void InvokeMethod(object sender, FileSystemEventArgs e)
  18:         {
  19:             Console.WriteLine("Change in file {0}", e.FullPath);
  20:         }
  21:     }