列舉網路芳鄰的網路資源
此範例會以遞迴方式列舉網路芳鄰的網路資源，在此範例中會使用到 mpr.dll API 函式庫的 WNetEnumResource、WNetOpenEnum、WNetCloseEnum 函式來進行網路芳鄰的網路資源的列舉動作。
TAPIMpr 類別為 mpr.dll API 函式庫的操作類別
1: ''' <summary>
2: ''' 網路芳鄰相關函式庫(mpr.dll)。
3: ''' </summary>
4: Public NotInheritable Class TAPIMpr
5: Public Enum EResourceScope As Integer
6: ''' <summary>
7: ''' 正連線的資源。
8: ''' </summary>
9: RESOURCE_CONNECTED = &H1 10: ''' <summary>
11: ''' 網路上所有的資源。
12: ''' </summary>
13: RESOURCE_GLOBALNET = &H2 14: ''' <summary>
15: ''' 曾經連線的資源。
16: ''' </summary>
17: RESOURCE_REMEMBERED = &H3 18: End Enum
19: 20: Public Enum EResourceType As Integer
21: ''' <summary>
22: ''' 所有網路資源。
23: ''' </summary>
24: RESOURCETYPE_ANY = &H0 25: ''' <summary>
26: ''' 網路磁碟機。
27: ''' </summary>
28: RESOURCETYPE_DISK = &H1 29: ''' <summary>
30: ''' 網路印表機。
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: ''' 伺服器資源。
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: ''' 網路資源定義。
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: ''' 列舉網路芳鄰的網路資源。
100: ''' </summary>
101: ''' <param name="Handle">從 WNetOpenEnum 函數返回的一個控制碼。</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">通常是一個位元組緩衝區的首位元組。該緩衝區裝載了列舉資訊。</param>
104: ''' <param name="Size">緩衝區大小。</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: ''' 啟動對網路資源進行列舉的過程。這個函數會返回由 WNetEnumResource 函數用於列舉資源所用的一個控制碼。
111: ''' </summary>
112: ''' <param name="Scope">要列舉的資源範圍。</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">網路資源定義。</param>
116: ''' <param name="Handle">傳出一個控制碼。該控制碼由 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控制碼。</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
下列程式碼中的 NetEnumResource 為列舉網路芳鄰的網路資源的函式，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">網路資源定義。</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: ''' 列舉網路芳鄰的網路資源。
10: ''' </summary>
11: ''' <param name="NetResource">網路資源定義。</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 則利用遞迴往下層列舉網路資源
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
在表單上放置一個 ListBox 控制項來顯示列舉的網路資源，呼叫 NetEnumResource 函式來進行列舉，呼叫 NetEnumResource 函式的引數需傳入事先定義好的 NetEnumResourceCallback 回呼函式；當列舉的過程式，當找到網路資源時就會執行 NetEnumResourceCallback 函式，利用傳入的 NetResource 引數就可以依序列舉網路資源。
1: ''' <summary>
2: ''' 執行 WNetEnumResource 方法的回呼函式。
3: ''' </summary>
4: ''' <param name="NetResource">網路資源定義。</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