Using .NET FileSystemWatcher to listen for new files

33 次查看（过去 30 天）
Jonathan Sykes
Jonathan Sykes 2011-6-21
评论： Mr.Dong 2019-12-25
Hi,
I want to write a simple program that runs continuously and listens for the FileSystemWatcher events i.e. a new file has appeared in a folder. When the file arrives I want to process that file in some way. The following is code that I have been playing with:
function ImageSorter
%Start listeners for file new notifications
fileObj = System.IO.FileSystemWatcher('C:\Dicom\');
fileObj.EnableRaisingEvents = true;
l1 = addlistener(fileObj, 'Created', @eventhandlerChanged);
%now I want the program to stop and listen for the events and not
% continue to the end.
h = figure('visible','off');
waitfor(h);
delete(l1);
end
function eventhandlerChanged(source,arg)
arg.FullPath
end
If I insert a break point at the end of the ImageSorter program then it works and the eventhandlerChanged function is called when a new file appears in the folder C:\DICOM.
How do I make the function stop running to the end and wait for the listening events?
Jonathan

请先登录，再回答此问题。

采纳的回答

Matthew Whitaker
Matthew Whitaker 2011-6-21
Jonathon, Here is an example of how to do it. Note you need to listen on the changed event and not the created event
function FileWatch(pathToWatch)
txtDetectedFiles = createFigure;
fileObj = System.IO.FileSystemWatcher(pathToWatch);
fileObj.EnableRaisingEvents = true;
changeListener =addlistener(fileObj, 'Changed', @onChange); %need to keep in scope
function txtDetectedFiles = createFigure
figHdl = figure('Name','FileWatcher',...
'Menubar','none',...
'Toolbar','none',...
'NumberTitle','off',...
'Units','normalized',...
'Position',[0.4,0.4,0.4,0.2]);
uicontrol('Parent',figHdl,...
'Style','text',...
'Units','normalized',...
'Position',[0.1,0.9,0.8,0.08],...
'String',['Path Watched: ',pathToWatch]);
uicontrol('Parent',figHdl,...
'Style','pushbutton',...
'String','Write a file to the watched path.',...
'Units','normalized',...
'Position',[0.1,0.6,0.5,0.2],...
'Callback',@cmdWriteFile);
txtDetectedFiles = uicontrol('Parent',figHdl,...
'Style','edit',...
'Enable','inactive',...
'Units','normalized',...
'Position',[0.1,0.05,0.8,0.45],...
'Max',3);
end %createFigure
function cmdWriteFile(varargin)
%create a simple text file in the watched folder
tName = tempname;
[~,tName] = fileparts(tName);
fName =fullfile(pathToWatch,[tName,'.txt']);
dlmwrite(fName,1:5);
end %cmdWriteFile
function onChange(~,evt)
existStr = get(txtDetectedFiles,'String');
if isempty(existStr)
existStr = {};
end %if
existStr{length(existStr)+1} = ['New file Detected: ',char(evt.FullPath.ToString())];
set(txtDetectedFiles,'String',existStr);
end %onChange
end %FileWatch
  3 个评论
显示 1更早的评论
Matthew Whitaker
Matthew Whitaker 2011-7-1
Great , glad it helped! Can you set that you accept the answer?
Thanks
Matt
Jagatpreet
Jagatpreet 2013-3-13
Your example was of great help. It provides me the answer to my two questions:
How can GUI be used while listening events
How to watch file system and send notification when new file is added programmatically.
Previously I was watching the file using timer function Thanks a lot

请先登录，再进行评论。

更多回答（1 个）

E
E 2016-4-7
Hi , Im trying to use this piece of code but i have no need in the button that creates new files so i commented the following lines:
uicontrol('Parent',figHdl,...
'Style','pushbutton',...
'String','Write a file to the watched path.',...
'Units','normalized',...
'Position',[0.1,0.6,0.5,0.2],...
'Callback',@cmdWriteFile);
and its corresponding callback:
function cmdWriteFile(varargin)
%create a simple text file in the watched folder
tName = tempname;
[~,tName] = fileparts(tName);
fName =fullfile(pathToWatch,[tName,'.txt']);
dlmwrite(fName,1:5);
end %cmdWriteFile
After doing so, the listener is not listening and onCahnge() is not running on change...
any ides how are my actions related to the listener?
Thanks!

类别

在 Help Center 和 File Exchange 中查找有关 Oscilloscopes 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by