Which filter of FileSystemWatcher do I need to use for finding new files

问题

So far I know that FileSystemWatcher can look into a folder and if any of the files inside that folder is changed,modifies,.etc... then we can handle it. But I am not sure which filter and event I should use in my scenario: Watch for a Folder, If a file is added to that folder, do XYZ ... So In my scenario I don't care if an existing file is changed,etc..those should be ignored...only do XYZ if and only if a new file has been added to that Folder...

Which event and filter do you recommended for this scenario?

回答1:

Set up the watcher:

FileSystemWatcher watcher = new FileSystemWatcher();
watcher.Path = "Blah";

watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
    | NotifyFilters.FileName;

watcher.Created += new FileSystemEventHandler(OnChanged);

watcher.EnableRaisingEvents = true;

Then implement the FileCreated delegate:

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

回答2:

Please look here for a detailed explanation of the FileSystemWatcher: http://www.c-sharpcorner.com/uploadfile/mokhtarb2005/fswatchermb12052005063103am/fswatchermb.aspx

You will have to look for created files if you want to look for added files.

You specify the type of change to watch for by setting the value of a WatcherChangeType enumeration. The possible values are as follows:

All: The creation, deletion, change, or renaming of a file or folder.
Changed: The change of a file or folder. The types of changes include: changes to size, attributes, security settings, last write, and last access time.
Created: The creation of a file or folder.
Deleted: The deletion of a file or folder.
Renamed: The renaming of a file or folder.

Also you may just wire up the event handler that fires if a file is created (added) and not implement all the other events since they are not interesting for you:

watcher.Created += new FileSystemEventHandler(OnChanged);

回答3:

Code with comments below may hopefully satisfy your needs.

public void CallingMethod() {

         using(FileSystemWatcher watcher = new FileSystemWatcher()) {
          //It may be application folder or fully qualified folder location
          watcher.Path = "Folder_Name";

          // 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.if you want to track other types then mentioned here
          watcher.Filter = "*.txt";

          // Add event handlers.for monitoring newly added files          
          watcher.Created += OnChanged;


          // Begin watching.
          watcher.EnableRaisingEvents = true;

         }


        }

        // Define the event handlers.
        private static void OnChanged(object source, FileSystemEventArgs e) {
        // Specify what is done when a file is  created with these properties below
        // e.FullPath , e.ChangeType
        }

来源：https://stackoverflow.com/questions/11072295/which-filter-of-filesystemwatcher-do-i-need-to-use-for-finding-new-files

标签

filesystemwatcher