Using .NET FileSystemWatcher to listen for new files

Question

Jonathan Sykes 2011-6-21

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/9957-using-net-filesystemwatcher-to-listen-for-new-files

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

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Ashish Uthama 2011-6-21

how about putting in a 'pause'?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Matthew Whitaker 2011-6-21

5
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/9957-using-net-filesystemwatcher-to-listen-for-new-files#answer_13710

在 MATLAB Online 中打开

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更早的评论隐藏 1更早的评论

Matthew Whitaker 2011-7-1

Great , glad it helped! Can you set that you accept the answer?

Thanks

Matt

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。

Answer 2

E 2016-4-7

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/9957-using-net-filesystemwatcher-to-listen-for-new-files#answer_216862

在 MATLAB Online 中打开

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