VB.NET中如何检查网络驱动器是否已映射？

你用WebClient的方法行不通，因为WebClient是针对HTTP/HTTPS这类Web协议设计的，而UNC路径（\\xxx格式）用的是SMB文件共享协议，两者不兼容，所以无法识别目标路径。Ping失效则大概率是目标服务器禁用了ICMP请求，或是防火墙拦截了ping包。

下面是几种可行的解决方案：

方案1：检查指定盘符是否映射到目标UNC路径 #

如果你的需求是确认某个盘符（比如Z:\）是否映射到目标共享路径，可以通过Windows API获取盘符对应的UNC地址，再做匹配：

Imports System.Runtime.InteropServices
Imports System.IO

Public Class NetworkDriveHelper
    ' 调用Windows API获取映射盘符对应的UNC路径
    <DllImport("mpr.dll", CharSet:=CharSet.Unicode, SetLastError:=True)>
    Private Shared Function WNetGetConnection(
        ByVal localName As String,
        ByVal remoteName As StringBuilder,
        ByRef length As Integer
    ) As Integer
    End Function

    ' 根据盘符获取对应的UNC路径
    Public Shared Function GetUncFromDrive(driveLetter As String) As String
        ' 统一盘符格式为 "X:\"
        If Not driveLetter.EndsWith(":\") Then
            driveLetter = $"{driveLetter}:\"
        End If

        Dim sb As New StringBuilder(512)
        Dim bufferLength As Integer = sb.Capacity
        Dim apiResult As Integer = WNetGetConnection(driveLetter, sb, bufferLength)

        ' API返回0表示成功获取
        Return If(apiResult = 0, sb.ToString(), String.Empty)
    End Function

    ' 检查指定盘符是否映射到目标UNC
    Public Shared Function IsDriveMappedToTarget(driveLetter As String, targetUnc As String) As Boolean
        Dim mappedUnc As String = GetUncFromDrive(driveLetter)
        Return String.Equals(mappedUnc, targetUnc, StringComparison.OrdinalIgnoreCase)
    End Function
End Class

使用示例：

' 检查Z盘是否映射到\\mynetowrk_Driver.com\system\application
Dim isMapped As Boolean = NetworkDriveHelper.IsDriveMappedToTarget("Z", "\\mynetowrk_Driver.com\system\application")
Console.WriteLine(isMapped)

方案2：直接验证UNC路径的可访问性 #

如果不需要检查盘符映射，只是确认目标共享路径是否能正常访问，可直接用Directory.Exists（针对目录）或File.Exists（针对文件），同时处理权限、网络异常：

Imports System.IO

Public Function IsUncPathAccessible(targetUnc As String) As Boolean
    Try
        ' 验证目录是否存在
        Return Directory.Exists(targetUnc)
        ' 如果是验证具体文件，替换为：
        ' Return File.Exists(Path.Combine(targetUnc, "你的应用文件名.exe"))
    Catch ex As Exception
        ' 捕获权限不足、网络中断等异常
        Return False
    End Try
End Function

使用示例：

Dim isAccessible As Boolean = IsUncPathAccessible("\\mynetowrk_Driver.com\system\application")
Console.WriteLine(isAccessible)

方案3：遍历所有已映射的网络驱动器 #

如果要确认目标UNC是否被映射为任意盘符，可以遍历系统中所有网络驱动器并检查：

Imports System.IO

Public Function IsUncMappedAsAnyDrive(targetUnc As String) As Boolean
    For Each drive As DriveInfo In DriveInfo.GetDrives()
        If drive.DriveType = DriveType.Network Then
            Dim mappedUnc As String = NetworkDriveHelper.GetUncFromDrive(drive.Name.TrimEnd("\"c))
            If String.Equals(mappedUnc, targetUnc, StringComparison.OrdinalIgnoreCase) Then
                Return True
            End If
        End If
    Next
    Return False
End Function

使用示例：

Dim isMapped As Boolean = IsUncMappedAsAnyDrive("\\mynetowrk_Driver.com\system\application")
Console.WriteLine(isMapped)

注意事项 #

• Directory.Exists需要当前程序拥有访问目标UNC路径的权限，否则会返回False
• WNetGetConnection只能获取当前用户会话下的映射驱动器
• 如果目标服务器禁用了文件共享、网络不通，上述方法都会返回False

内容的提问来源于stack exchange，提问作者NBB