How to modify the default Web browser and e-mail client programmatically in Windows XP

Summary

On a Windows XP-based computer, Windows XP sets the default Start menu Internet browser to Microsoft Internet Explorer and e-mail client to Microsoft Outlook Express. The Start menu Internet browser only controls the application that is started when you click the Internet or E-mail icon on the Start menu. This is separate from the default Web browser or e-mail client that is used to start arbitrary URLs from anywhere in the system. You can programmatically change the defaults for the system or individually for each user.

More Information

By default, Windows XP uses a global setting in the HKeyLocalMachine (HKLM) Registry key to set an initial, default e-mail and Web browser client from the Start menu. Windows XP also implements new registry keys in HKeyCurrentUser (HKCU) to store individual internet and e-mail client information for each user as part of their profile if users select a different client than the default. The following code sample adds a Web browsing and e-mail client to the available options on the system and shows how to modify both the global and the current user:
  1. Create a new Microsoft Visual Basic "Standard EXE" project.
  2. On the Project menu, click Add Module, click Module, and then click Open.
  3. Double-click the new module that you created, and then paste the following code into the code module.
    Const REG_SZ As Long = 1
    Const HKEY_CURRENT_USER = &H80000001
    Const HKEY_LOCAL_MACHINE = &H80000002
    Const KEY_SET_VALUE = &H2
    Const KEY_ALL_ACCESS = &H3F
    Const REG_OPTION_NON_VOLATILE = 0
    Const HWND_BROADCAST = &HFFFF
    Const WM_SETTINGCHANGE = &H1A



    Private Declare Function RegCloseKey Lib "advapi32.dll" _
    (ByVal hKey As Long) As Long
    Private Declare Function RegCreateKeyEx Lib "advapi32.dll" _
    Alias "RegCreateKeyExA" (ByVal hKey As Long, _
    ByVal lpSubKey As String, ByVal Reserved As Long, _
    ByVal lpClass As String, ByVal dwOptions As Long, _
    ByVal samDesired As Long, ByVal lpSecurityAttributes As Long, _
    phkResult As Long, lpdwDisposition As Long) As Long
    Private Declare Function RegOpenKeyEx Lib "advapi32.dll" _
    Alias "RegOpenKeyExA" (ByVal hKey As Long, _
    ByVal lpSubKey As String, ByVal ulOptions As Long, _
    ByVal samDesired As Long, phkResult As Long) As Long
    Private Declare Function RegSetValueExString Lib "advapi32.dll" _
    Alias "RegSetValueExA" (ByVal hKey As Long, _
    ByVal lpValueName As String, ByVal Reserved As Long, _
    ByVal dwType As Long, ByVal lpValue As String, _
    ByVal cbData As Long) As Long
    Private Declare Function SendMessage Lib "user32" _
    Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _
    ByVal wParam As Long, lparam As String) As Long
    Public Function SetClient(iClient As Integer, sDisplayName As String, _
    sClientCommandLine As String, sClientResourceDLL As String, _
    iLocalization As Integer, bGlobalClient As Boolean, _
    Optional sCLParameters As String, Optional bMakeDefault As Boolean) As Integer

    ' iClient - 1 for internet browser, 2 for e-mail client
    ' sDisplayName - the name to be displayed on the menu for the client
    ' sClientCommandLine - the path and filename of the e-mail client
    '
    ' The next two parameters are included for localization of the client.
    ' For backwards compatibility with applications that do not support localized
    ' strings, the name of the application in the installed language should be set
    ' as the Default value for the key.
    ' sClientResourceDLL - provides a path to an EXE or DLL containing the
    ' localized strings for the client.
    ' iLocalization - a string resource ID within the DLL whose value is
    ' to be displayed to the user allowing the same registration to
    ' be used for multiple languages. For each language, provide a
    ' different Resource DLL, and the dynamic loading of the string
    ' from the DLL results in the correct strings being displayed, depending
    ' on the language.
    '
    ' bGlobalClient - sets the value for either all users (True) or the
    ' current user (False)
    ' sCLParameters - additional parameters on the command line to be passed to the
    ' browser or e-mail client.
    ' bMakeDefault - (Optional) set the browser or e-mail application as the default

    Dim iStatus As Integer
    Dim hHandle As Long
    Dim hGRegKey As String
    Dim hLRegKey As String
    Dim sCommand As String
    Dim sKey As String
    Dim sAll As String
    Dim sRoot As String
    Dim hKey As Long
    Dim sLoc As String
    hGRegKey = HKEY_LOCAL_MACHINE
    hLRegKey = HKEY_CURRENT_USER


    If iClient = 1 Then
    sRoot = "Software\Clients\StartMenuInternet"
    Else
    sRoot = "Software\Clients\Mail"
    End If

    ' Create and null terminate needed strings
    sCommand = "shell\open\command"
    sKey = sRoot & "\" & sDisplayName
    sAll = sKey & "\" & sCommand
    sLoc = "@" & sClientResourceDLL & "," & iLocalization & Chr$(0)
    sClientLocation = """" & sClientCommandLine & """" & _
    IIf(sCLParameters <> "", " ", "") & Trim(sCLParameters) & Chr$(0)
    sDisplayName = sDisplayName & Chr$(0)

    ' Create a registry key for the new client
    iStatus = RegCreateKeyEx(hGRegKey, sKey, 0&, vbNullString, _
    REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, hNewKey, lRetVal)
    iStatus = RegCreateKeyEx(hGRegKey, sAll, 0&, vbNullString, _
    REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, hNewKey, lRetVal)
    If iStatus = ERROR_NONE Then
    iStatus = RegOpenKeyEx(hGRegKey, sAll, 0, KEY_SET_VALUE, hKey)
    iStatus = RegSetValueExString(hKey, "", 0&, REG_SZ, sClientLocation, _
    Len(sClientLocation))
    iStatus = RegCloseKey(hKey)
    iStatus = RegOpenKeyEx(hGRegKey, sKey, 0, KEY_SET_VALUE, hKey)
    iStatus = RegSetValueExString(hKey, "", 0&, REG_SZ, sDisplayName, _
    Len(sDisplayName))
    ' Add the localization string
    iStatus = RegSetValueExString(hKey, "LocalizedString", 0&, REG_SZ, _
    sLoc, Len(sLoc))
    iStatus = RegCloseKey(hKey)
    Else
    SetClient = iStatus
    Exit Function
    End If

    ' Sets browser as local or global default if specified
    If bMakeDefault Then
    If bGlobalClient Then
    iStatus = RegOpenKeyEx(hGRegKey, sRoot, 0, KEY_SET_VALUE, hKey)
    iStatus = RegSetValueExString(hKey, "", 0&, REG_SZ, sDisplayName, _
    Len(sDisplayName))
    iStatus = RegCloseKey(hKey)
    Else
    iStatus = RegCreateKeyEx(hLRegKey, sRoot, 0&, vbNullString, _
    REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, hNewKey, lRetVal)
    iStatus = RegSetValueExString(hNewKey, "", 0&, REG_SZ, _
    sDisplayName, Len(sDisplayName))
    iStatus = RegCloseKey(hNewKey)
    End If
    UpdateMenus
    End If
    End Function
    Private Sub UpdateMenus()
    ' Refresh the menu choices with the updated client
    Dim iRetVal As Integer
    iRetVal = SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, _
    "SOFTWARE\Clients\mail")
    iRetVal = SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, _
    "SOFTWARE\Clients\StartMenuInternet")
    End Sub
    Here are examples of calling this function in the module.
    Dim x As Integer
    ' Sets up a browser for the current user and makes it default
    x = SetClient(1, "My Browser", "C:\Program Files\MyBrowser\mybrowser.exe", "C:\Program Files\MyBrowser\localization.dll", -123, True, "-homepage", False)
    ' Sets up an e-mail client for the current user and makes it default
    x = SetClient(2, "My E-mail", "C:\Program Files\MyEmail\myemail.exe", "C:\Program Files\MyEmail\localization.dll", -456, True, "-inbox", False)
  4. Call the function in the module as follows.
    Dim x As Integer
    ' Sets up a browser for the current user and makes it default
    x = SetClient(1, "My Browser", "C:\Program Files\MyBrowser\mybrowser.exe", "C:\Program Files\MyBrowser\localization.dll", -123, True, "-homepage", False)
    ' Sets up an e-mail client for the current user and makes it default
    x = SetClient(2, "My E-mail", "C:\Program Files\MyEmail\myemail.exe", "C:\Program Files\MyEmail\localization.dll", -456, True, "-inbox", False)
  5. On the File menu, click Make Project.exe, type a name for the project, and then click OK.

    Note Project is a placeholder for the name of the project.
  6. Double-click Project.exe to run the program.

References

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

145679 How to use the registry API to save and retrieve setting

Propriedades

ID do Artigo: 299853 - Última Revisão: 13 de jul de 2009 - Revisão: 1

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