Visual Basic 6.0(以下简称VB
6)以其强大的功能为广大软件开发人员所喜爱,被用来开发各种应用程序。随着Internet的迅猛发展,VB6在网络方面的应用开发也越来越多。本文介绍笔者在实际编程开发中总结的5个技巧,希望能为进行网络开发的朋友们提供一点参考。
连通检测
许多应用程序常常需要在程序中直接进行联网操作,以便进行一些必要的处理(如在线注册和在线帮助等),这就要求我们在程序中建立某些连接。很多软件在不知用户是否联网的情况下就启动浏览器查找网址,结果只能查出一错误网页,既浪费用户时间又没有任何效果。如果应用程序在查找网页之前能自动判断用户是否已经联网,就会节约许多时间,提高程序运行效率。
下面是实现网络连通检测的VB 6代码:
Private Sub Form_Load() If IsConnected = TRUE Then MsgBox
("您已经连通了Internet!") End If If IsConnected = FALSE Then
MsgBox ("您还没有连通 Internet!") End If End Sub
Option
Explicit /*有关的API声明和定义*/ Public Declare Function
RasEnumConnections Lib "RasApi32.dll" Alias "RasEnumConnectionsA"
(lpRasCon As Any, lpcb As Long, lpcConnections As Long) As Long
Public Declare Function RasGetConnectStatus Lib "RasApi32.dll" Alias
"RasGetConnectStatusA" (ByVal hRasCon As Long, lpStatus As Any) As Long
/*常数和变量的设定*/ Public Const RAS95_MaxEntryName = 256 Public
Const RAS95_MaxDeviceType = 16 Public Const RAS95_MaxDeviceName = 32
Public Type RASCONN95 dwSize As Long hRasCon As Long
szEntryName(RAS95_MaxEntryName) As Byte
szDeviceType(RAS95_MaxDeviceType) As Byte
szDeviceName(RAS95_MaxDeviceName) As Byte End Type
Public
Type RASCONNSTATUS95 dwSize As Long RasConnState As Long
dwError As Long szDeviceType(RAS95_MaxDeviceType) As Byte
szDeviceName(RAS95_MaxDeviceName) As Byte End Type
/*函数IsConnected返回连通的状态,如果为True则表示已连通*/
Public Function
IsConnected() As Boolean Dim TRasCon(255) As RASCONN95 Dim lg As
Long Dim lpcon As Long Dim RetVal As Long Dim Tstatus As
RASCONNSTATUS95 TRasCon(0).dwSize = 412 lg = 256 *
TRasCon(0).dwSize RetVal = RasEnumConnections(TRasCon(0), lg, lpcon)
If RetVal <> 0 Then MsgBox "错误" Exit Function
End If Tstatus.dwSize = 160 RetVal =
RasGetConnectStatus(TRasCon(0).hRasCon,Tstatus) If
Tstatus.RasConnState = &H2000 Then IsConnected = TRUE Else
IsConnected = FALSE End If End Function
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