我们正在运行一个流程，它会在特定事件上创建文件并写入数据。文件在文件夹中创建：C：\\EventListenerFolder \\。现在每当创建一个新文件并将数据写入文件时，我们都需要发送邮件。 public static void RunEventListenerPrgm （） { //邮件通知必须在C：\\ EventListenerFolder \\ $ b生成文件时$ b while（true） { System.IO.FileSystemWatcher m_Watcher = new System.IO.FileSystemWatcher（）; m_Watcher.Filter =* .txt; m_Watcher.Path =C：\\EventListenerFolder \\; m_Watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName; m_Watcher.Changed + = new FileSystemEventHandler（OnChanged）; m_Watcher.EnableRaisingEvents = true; } } public static void OnChanged（object sender，FileSystemEventArgs e） { string stringReceived; string [] allFiles = System.IO.Directory.GetFiles（C：\\ EventListenerFolder \\）; foreach（字符串文件in allFiles） { Console.WriteLine（EventListener找到匹配文件。文件名：+文件）; 试试 { stringReceived = System.IO.File.ReadAllText（file）; } catch（Exception ex） { 继续; //以避免在写入文件时读取文件。因此我们等到文件被写入然后我们才读到它 } SendMailFunction（stringReceived）; File.Delete（file）; } } 在这种情况下，我们得到100 +邮件为同一个文件。我们只想发送一个邮件发送给一个文件。 我尝试了什么： 尝试更改m_Watcher.Changed + = new FileSystemEventHandler（OnChanged）; 到m_Watcher.Created + = new FileSystemEventHandler（OnChanged）; 仍然不起作用。 可能是我正在使用的文件监视器事件过滤器不正确吗？ 你可以帮我一下吗？
There is a process we are running, which creates files and writes data on a particular event. File is created in folder: C:\\EventListenerFolder\\ . Now whenever a new file is created and data is written to the file, we need to send a mail. public static void RunEventListenerPrgm() { //the mail notification has to go as a file gets generated in C:\\EventListenerFolder\\ while (true) { System.IO.FileSystemWatcher m_Watcher = new System.IO.FileSystemWatcher(); m_Watcher.Filter = "*.txt"; m_Watcher.Path = "C:\\EventListenerFolder\\"; m_Watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName; m_Watcher.Changed += new FileSystemEventHandler(OnChanged); m_Watcher.EnableRaisingEvents = true; } } public static void OnChanged(object sender, FileSystemEventArgs e) { string stringReceived; string[] allFiles = System.IO.Directory.GetFiles("C:\\EventListenerFolder\\"); foreach (string file in allFiles) { Console.WriteLine("EventListener Match File Found. FILE NAME : " + file); try { stringReceived = System.IO.File.ReadAllText(file); } catch (Exception ex) { continue; // to avoid reading of file when it is in process of being written . hence we wait till the file is written and then we read it } SendMailFunction(stringReceived); File.Delete(file); } } In this scenario, we are getting 100+ mail for the same file. And we want only one mail for one file to be sent. What I have tried: Tried changing m_Watcher.Changed += new FileSystemEventHandler(OnChanged); to m_Watcher.Created+= new FileSystemEventHandler(OnChanged); still doesnot work. Could it be that the file watcher event Filter I am using is incorrect? Could you please help me on the same?
推荐答案这么多问题;从哪里开始？ :) 您的 OnChanged 事件处理程序忽略了有关 文件已更改的信息，并为该文件夹中的所有文件发送通知。您应该使用 e.FullName 来处理已更改的文件： So many problems; where to begin? :) Your OnChanged event handler is ignoring the information about which file changed, and sending a notification for all files in the folder. You should use e.FullName to process just the file which has changed: private static void OnChanged(object sender, FileSystemEventArgs e) { string file = e.FullName; Console.WriteLine("EventListener Match File Found. FILE NAME : {0}", file); try { string stringReceived = File.ReadAllText(file); SendMailFunction(stringReceived); File.Delete(file); } catch (IOException) { } }
您的 RunEventListenerPrgm 方法正在紧密循环中创建多个新的 FileSystemWatcher 实例。您创建的每个实例都会在每次更改文件时触发 OnChanged 处理程序。我很惊讶你只收到了一个单个文件的数百条消息！ 该方法永远不会干净地终止，所以快速而肮脏的修复会是在循环之外移动 FileSystemWatcher 实例的创建：
Your RunEventListenerPrgm method is creating multiple new FileSystemWatcher instances in a tight loop. Every single instance you create is going to trigger the OnChanged handler every time a file is changed. I'm amazed that you only managed to receive hundreds of messages for a single file! The method will never terminate cleanly, so a quick-and-dirty fix would be to move the creation of the FileSystemWatcher instance outside of the loop:
public static void RunEventListenerPrgm() { var m_Watcher = new System.IO.FileSystemWatcher { Filter = "*.txt", Path = @"C:\EventListenerFolder\", NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName }; m_Watcher.Created += OnChanged; m_Watcher.EnableRaisingEvents = true; while (true) { } }但是，一旦程序运行，这可能会占用你CPU核心的100％！ 稍微好一点的选择是使用 WaitForChanged 方法：
However, this will probably consume 100% of one of your CPU cores all the time the program is running! A slightly better alternative would be to use the WaitForChanged method:
public static void RunEventListenerPrgm() { var m_Watcher = new System.IO.FileSystemWatcher { Filter = "*.txt", Path = @"C:\EventListenerFolder\", NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName }; while (true) { WaitForChangedResult result = m_Watcher.WaitForChanged(WatcherChangeTypes.Created | WatcherChangeTypes.Changed); if (!result.TimedOut) { OnChanged(result.Name); } } } private static void OnChanged(string file) { Console.WriteLine("EventListener Match File Found. FILE NAME : {0}", file); try { string stringReceived = File.ReadAllText(file); SendMailFunction(stringReceived); File.Delete(file); } catch (IOException) { } }理想情况下，您需要找到一些方法在应用程序关闭时通知方法，以便它可以干净地停止循环。 最后，有一个已知问题， FileSystemWatcher 可以为同一个更改生成多个事件。有很多可以找到的解决方法 - 例如： FileSystemWatcher更改的事件被引发两次 - Stack Overflow [ ^ ] FileSystemWatcher生成重复事件 - 如何解决方法 - BizTalk 2006 - Windows SharePoint Services适配器 [ ^ ]
Ideally, you'd need to find some way to notify the method when your application was closing, so that it could stop the loop cleanly. Finally, there is a known issue where the FileSystemWatcher can generate multiple events for the same change. There are numerous workarounds to be found - for example: FileSystemWatcher Changed event is raised twice - Stack Overflow[^] FileSystemWatcher generates duplicate events – How to workaround – BizTalk 2006 – Windows SharePoint Services adapter[^]
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每次在文件夹中创建文件时如何使用filesystemwatcher并发送邮件？
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