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在浏览了许多网站和一些教程视频之后，我仍然对这个感到困惑。我正在完成一个程序，我需要添加最后一点功能。

该程序以这种方式工作。用户在 textbox1 中指定一个文件，然后在 textbox2 中指定一个目录。用户通过在 textbox3 中复制文件来设置他们希望文件的频率。用户点击运行，程序将文件复制到新位置，每次复制时在文件名中添加一个数字（以避免覆盖）。一切正常，但我希望用户可以选择按时间复制文件或在修改文件时复制文件。

如何使用 FileSystemWatcher 在目录中查找修改（在 textbox1 中给出），然后调用将指定目录复制到目标目标的语句（在文本框 2 中指定）？

附加说明：

在一个教程中，通过这样做设置了 FileSystemWatcher 路径

Dim watched As String = System.IO.Path.Combine(Environment.GetEnvironmentVariable("USERPROFILE"), "Pictures")
        Dim fsw As New FileSystemWatcher(watched)

代码指向的路径是 "C:\Users[User Name]\Pictures" 。我在网上找不到显示“.GetEnvironmentVariable”接受哪些变量甚至变量含义的资源。这是我在使用最后一位代码时遇到问题的众多原因之一。

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2 回答 2

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GetEnvironmentVariable返回当前进程的指定环境的值。

在您的示例中，USERPROFILE是当前用户文件夹的路径。例如，在我的笔记本电脑上，USERPROFILE 是 C:\Users\Tim。

的输出System.IO.Path.Combine(Environment.GetEnvironmentVariable("USERPROFILE"), "Pictures")将是 USERPROFILE 路径加上“图片” - 继续我的示例，它将是C:\Users\Tim\Pictures- 这是我的用户帐户的 My Pictures 文件夹的物理路径。

要获取所有环境变量的列表，如果您好奇，请转到 DOS 提示符并输入SET并按回车键。

要回答您最初的问题，您需要处理FileSystemWatcher.Changed Event。

例如：

Private Shared Sub OnChanged(source As Object, e As RenamedEventArgs)

   ' Do your copy here
End Sub

您可以FileWatcher像这样将事件处理程序挂钩：

AddHandler fsw.Changed, AddressOf OnChanged

但是，请注意 MSDN 文档中的此警告。

Common file system operations might raise more than one event. For example, when a file is moved from one directory to another, several OnChanged and some OnCreated and OnDeleted events might be raised. Moving a file is a complex operation that consists of multiple simple operations, therefore raising multiple events. Likewise, some applications (for example, antivirus software) might cause additional file system events that are detected by FileSystemWatcher.

于 2013-05-11T07:32:06.933 回答
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这是我使用的代码，它可以满足我的要求。

Option Explicit On
Option Strict On
Imports System.IO
Imports Microsoft.VisualBasic ' I don't know this one, but the code worked without this.
Imports System.Security.Permissions ' I don't know the exactly what this does but the
  ' http://msdn.microsoft.com/ site did this, I assume it'f to allow for permission to 
  ' watch files? The code still worked for me without this

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Me.Load

        Dim directoryPath As String = Path.GetDirectoryName(TextBox1.Text)
        Dim varFileSystemWatcher As New FileSystemWatcher()
        varFileSystemWatcher.Path = directoryPath

        varFileSystemWatcher.NotifyFilter = (NotifyFilters.LastWrite)

        varFileSystemWatcher.Filter = Path.GetFileName(TextBox1.Text) ' I know this
           ' limits what's being watched to one file, but right now this is 
           ' what I want the program to do.

        AddHandler varFileSystemWatcher.Changed, AddressOf OnChanged


        varFileSystemWatcher.EnableRaisingEvents = True


    End Sub

    Private Sub OnChanged(source As Object, ByVal e As FileSystemEventArgs)

        My.Computer.FileSystem.CopyFile(e.FullPath, TextBox2.Text & "\" & e.Name, True)

    End Sub
于 2013-05-11T15:14:20.097 回答