此范例會以遞歸方式列舉網絡芳鄰的網絡資源，在此范例中會使用到 mpr.dll API 函式庫的 WNetEnumResource、WNetOpenEnum、WNetCloseEnum 函式來進行網絡芳鄰的網絡資源的列舉動作。

TAPIMpr 類別為 mpr.dll API 函式庫的操作類別

1: ''' <summary> 2: ''' 網絡芳鄰相關函式庫(mpr.dll)。 3: ''' </summary> 4: Public NotInheritable Class TAPIMpr 5: Public Enum EResourceScope As Integer 6: ''' <summary> 7: ''' 正聯機的資源。 8: ''' </summary> 9: RESOURCE_CONNECTED = &H1 10: ''' <summary> 11: ''' 網絡上所有的資源。 12: ''' </summary> 13: RESOURCE_GLOBALNET = &H2 14: ''' <summary> 15: ''' 曾經聯機的資源。 16: ''' </summary> 17: RESOURCE_REMEMBERED = &H3 18: End Enum 19: 20: Public Enum EResourceType As Integer 21: ''' <summary> 22: ''' 所有網絡資源。 23: ''' </summary> 24: RESOURCETYPE_ANY = &H0 25: ''' <summary> 26: ''' 網絡磁盤驅動器。 27: ''' </summary> 28: RESOURCETYPE_DISK = &H1 29: ''' <summary> 30: ''' 網絡打印機。 31: ''' </summary> 32: RESOURCETYPE_PRINT = &H2 33: ''' <summary> 34: ''' 未知。 35: ''' </summary> 36: RESOURCETYPE_UNKNOWN = &HFFFFFFFF 37: End Enum 38: 39: Public Enum EResourceDisplayType As Integer 40: ''' <summary> 41: ''' 一般資源。 42: ''' </summary> 43: RESOURCEDISPLAYTYPE_GENERIC = 0 44: ''' <summary> 45: ''' 網域資源。 46: ''' </summary> 47: RESOURCEDISPLAYTYPE_DOMAIN = 1 48: ''' <summary> 49: ''' 服務器資源。 50: ''' </summary> 51: RESOURCEDISPLAYTYPE_SERVER = 2 52: ''' <summary> 53: ''' 共享資源。 54: ''' </summary> 55: RESOURCEDISPLAYTYPE_SHARE = 3 56: ''' <summary> 57: ''' 檔案資源。 58: ''' </summary> 59: RESOURCEDISPLAYTYPE_FILE = 4 60: RESOURCEDISPLAYTYPE_GROUP = 5 61: RESOURCEDISPLAYTYPE_NETWORK = 6 62: RESOURCEDISPLAYTYPE_ROOT = 7 63: RESOURCEDISPLAYTYPE_SHAREADMIN = 8 64: RESOURCEDISPLAYTYPE_DIRECTORY = 9 65: RESOURCEDISPLAYTYPE_TREE = 10 66: RESOURCEDISPLAYTYPE_NDSCONTAINER = 11 67: End Enum 68: 69: Public Enum EResourceUsage As Integer 70: RESOURCEUSAGE_CONNECTABLE = &H1 71: RESOURCEUSAGE_CONTAINER = &H2 72: RESOURCEUSAGE_NOLOCALDEVICE = &H4 73: RESOURCEUSAGE_SIBLING = &H8 74: RESOURCEUSAGE_ATTACHED = &H10 75: RESOURCEUSAGE_ALL = (RESOURCEUSAGE_CONNECTABLE Or RESOURCEUSAGE_CONTAINER Or RESOURCEUSAGE_ATTACHED) 76: RESOURCEUSAGE_RESERVED = &H80000000 77: End Enum 78: 79: ''' <summary> 80: ''' 網絡資源定義。 81: ''' </summary> 82: <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Auto)> _ 83: Public Class TNetResource 84: Public dwScope As EResourceScope 85: Public dwType As EResourceType 86: Public dwDisplayType As EResourceDisplayType 87: Public dwUsage As EResourceUsage 88: <MarshalAs(UnmanagedType.LPTStr)> _ 89: Public LocalName As String 90: <MarshalAs(UnmanagedType.LPTStr)> _ 91: Public RemoteName As String 92: <MarshalAs(UnmanagedType.LPTStr)> _ 93: Public Comment As String 94: <MarshalAs(UnmanagedType.LPTStr)> _ 95: Public Provider As String 96: End Class 97: 98: ''' <summary> 99: ''' 列舉網絡芳鄰的網絡資源。 100: ''' </summary> 101: ''' <param name="Handle">從 WNetOpenEnum 函數返回的一個句柄。</param> 102: ''' <param name="Count">最初設為要枚舉的最大資源數量；或設為-1，表示枚舉盡可能多的資源。一旦返回，就會設為實際枚舉的資源數量。</param> 103: ''' <param name="NetResource">通常是一個字節緩沖區的首字節。該緩沖區裝載了列舉信息。</param> 104: ''' <param name="Size">緩沖區大小。</param> 105: <DllImport("mpr.dll", CharSet:=CharSet.Auto)> _ 106: Public Shared Function WNetEnumResource(ByVal Handle As IntPtr, ByRef Count As Integer, ByVal NetResource As IntPtr, ByRef Size As Integer) As Integer 107: End Function 108: 109: ''' <summary> 110: ''' 啟動對網絡資源進行列舉的過程。這個函數會返回由 WNetEnumResource 函數用于列舉資源所用的一個句柄。 111: ''' </summary> 112: ''' <param name="Scope">要列舉的資源范圍。</param> 113: ''' <param name="Type">要列舉的資源類型。</param> 114: ''' <param name="Usage">要列舉的資源使用狀況。</param> 115: ''' <param name="NetResource">網絡資源定義。</param> 116: ''' <param name="Handle">傳出一個句柄。該句柄由 WNetEnumResource 函數使用。必須用 WNetCloseEnum 函數將其清除。</param> 117: <DllImport("mpr.dll", CharSet:=CharSet.Auto)> _ 118: Public Shared Function WNetOpenEnum(ByVal Scope As EResourceScope, ByVal Type As EResourceType, ByVal Usage As EResourceUsage, ByVal NetResource As TNetResource, <Out()> ByRef Handle As IntPtr) As Integer 119: End Function 120: 121: ''' <summary> 122: ''' 結束列舉操作。 123: ''' </summary> 124: ''' <param name="Handle">由 WNetOpenEnum 函數返回的一個列舉句柄。</param> 125: <DllImport("mpr.dll", CharSet:=CharSet.Auto)> _ 126: Public Shared Function WNetCloseEnum(ByVal Handle As IntPtr) As Integer 127: End Function 128: 129: End Class

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下列程序代碼中的 NetEnumResource 為列舉網絡芳鄰的網絡資源的函式，NetEnumResourceCallback 為執行 NetEnumResource 方法的回呼函式。

1: ''' <summary> 2: ''' 執行 NetEnumResource 方法的回呼函式。 3: ''' </summary> 4: ''' <param name="NetResource">網絡資源定義。</param> 5: ''' <param name="Cancel">是否取消列舉動作。</param> 6: Public Delegate Sub NetEnumResourceCallback(ByVal NetResource As TAPIMpr.TNetResource, ByRef Cancel As Boolean) 7: 8: ''' <summary> 9: ''' 列舉網絡芳鄰的網絡資源。 10: ''' </summary> 11: ''' <param name="NetResource">網絡資源定義。</param> 12: ''' <param name="CallBack">列舉過程中的回呼函式。</param> 13: Public Shared Sub NetEnumResource(ByVal NetResource As TAPIMpr.TNetResource, ByVal CallBack As NetEnumResourceCallback) 14: Dim bCancel As Boolean 15: Dim iRet As Integer 16: Dim oHandle As IntPtr = New IntPtr() 17: Dim iEntries As Integer 18: Dim iBuffer As Integer = 16384 19: Dim oBuffer As IntPtr 20: Dim oNetResource As TAPIMpr.TNetResource 21: Dim iPtr As Int32 22: Dim N1 As Integer 23: Dim oStructure As Object 24: 25: bCancel = False 26: Try 27: iRet = TAPIMpr.WNetOpenEnum( _ 28: TAPIMpr.EResourceScope.RESOURCE_GLOBALNET, _ 29: TAPIMpr.EResourceType.RESOURCETYPE_ANY, _ 30: TAPIMpr.EResourceUsage.RESOURCEUSAGE_ALL, NetResource, oHandle) 31: If iRet <> 0 Then Exit Sub 32: 33: oBuffer = Marshal.AllocHGlobal(iBuffer) 34: Do 35: iEntries = -1 36: iBuffer = 16384 37: iRet = TAPIMpr.WNetEnumResource(oHandle, iEntries, oBuffer, iBuffer) 38: If iRet <> 0 OrElse iEntries < 1 Then Exit Sub 39: iPtr = oBuffer.ToInt32 40: For N1 = 0 To iEntries - 1 41: oStructure = Marshal.PtrToStructure(CType(iPtr, IntPtr), GetType(TAPIMpr.TNetResource)) 42: oNetResource = DirectCast(oStructure, TAPIMpr.TNetResource) 43: 44: '列舉過程中的回呼函式 45: CallBack.Invoke(oNetResource, bCancel) 46: If bCancel = True Then Exit Do 47: 48: '若為 RESOURCEUSAGE_CONTAINER 則利用遞歸往下層列舉網絡資源 49: If (TAPIMpr.EResourceUsage.RESOURCEUSAGE_CONTAINER = _ 50: (oNetResource.dwUsage And TAPIMpr.EResourceUsage.RESOURCEUSAGE_CONTAINER)) Then 51: NetEnumResource(oNetResource, CallBack) 52: End If 53: iPtr = iPtr + Marshal.SizeOf(oNetResource) 54: Next 55: Loop 56: 57: Marshal.FreeHGlobal(oBuffer) 58: TAPIMpr.WNetCloseEnum(oHandle) 59: Catch ex As Exception 60: End Try 61: End Sub

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在窗體上放置一個 ListBox 控件來顯示列舉的網絡資源，呼叫 NetEnumResource 函式來進行列舉，呼叫 NetEnumResource 函式的自變量需傳入事先定義好的 NetEnumResourceCallback 回呼函式；當列舉的過程序，當找到網絡資源時就會執行 NetEnumResourceCallback 函式，利用傳入的 NetResource 自變量就可以依序列舉網絡資源。

1: ''' <summary> 2: ''' 執行 WNetEnumResource 方法的回呼函式。 3: ''' </summary> 4: ''' <param name="NetResource">網絡資源定義。</param> 5: ''' <param name="Cancel">是否取消列舉動作。</param> 6: Public Sub NetEnumResourceCallback(ByVal NetResource As TAPIMpr.TNetResource, ByRef Cancel As Boolean) 7: Dim sText As String 8: 9: sText = String.Format(" {0} : LocalName='{1}' RemoteName='{2}'", NetResource.dwDisplayType.ToString, NetResource.LocalName, NetResource.RemoteName) 10: ListBox1.Items.Add(sText) 11: Application.DoEvents() 12: End Sub 13: 14: Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click 15: Me.Cursor = Cursors.WaitCursor 16: Try 17: ListBox1.Items.Clear() 18: TBMpr.NetEnumResource(Nothing, New NetEnumResourceCallback(AddressOf NetEnumResourceCallback)) 19: MsgBox("執行完成!") 20: Finally 21: Me.Cursor = Cursors.Default 22: End Try 23: End Sub

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