如何在VB中实现ActiveX控件的IobjectSafety接口

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总述

本文叙述了如何在VB中实现控件的IobjectSafety接口，以标志该控件是脚本安全和初始化安全的。VB控件默认的处理方式是在注册表中注册组件类来标识其安全性，但实现IobjectSafety接口是更好的方法。本言语包括了实现过程中所需的所有代码。

请注意，控件只有确确实实是安全的，才能被标识为“安全的”。本文并未论及如何确保控件的安全性，这个问题请参阅Internet Client Software Development Kit (SDK)中的相关文档 "Safe Initialization and Scripting for ActiveX Controls"，它在Component Development 栏目中。

相关信息：

<此处略去了一段也许无关紧要的警告>

现在开始循序渐进地举例说明怎样创建一个简单的VB控件，以及怎样将它标识为脚本安全和初始化安全。

首先新建一个文件夹来存放在本例中所产生的文件。

从VB CD-ROM取得OLE 自动化类库的制作工具。将VB安装光盘中\Common\Tools\VB\Unsupprt\Typlib\目录下所有内容一并拷贝到前面新建的项目文件夹中。

把下列内容拷贝到“记事本”中，然后保存到上述文件夹，文件名为Objsafe.odl：

[

uuid(C67830E0-D11D-11cf-BD80-00AA00575603),

helpstring("VB IObjectSafety Interface"),

version(1.0)

]

library IObjectSafetyTLB

{

importlib("stdole2.tlb");

[

uuid(CB5BDC81-93C1-11cf-8F20-00805F2CD064),

helpstring("IObjectSafety Interface"),

odl

]

interface IObjectSafety:IUnknown {

[helpstring("GetInterfaceSafetyOptions")]

HRESULT GetInterfaceSafetyOptions(

[in] long riid,

[in] long *pdwSupportedOptions,

[in] long *pdwEnabledOptions);

[helpstring("SetInterfaceSafetyOptions")]

HRESULT SetInterfaceSafetyOptions(

[in] long riid,

[in] long dwOptionsSetMask,

[in] long dwEnabledOptions);

}

}

在命令行提示符下切换到项目文件夹，输入下列命令创建一个.tlb 文件：

MKTYPLIB objsafe.odl /tlb objsafe.tlb

在VB中新建一个ActiveX Control 项目。修改属性，把项目命名为IobjSafety，控件命名为DemoCtl。在控件上放置一个按钮，命名为cmdTest，在它的Click事件中加入一句代码 MsgBox "Test" 。

打开菜单“工程->引用”，点“浏览”，找到刚刚建立的Objsafe.tlb，把它加入到引用中。

增加一个新module名为basSafeCtl，并在其中加入下列代码：

Option Explicit

Public Const IID_IDispatch = "{00020400-0000-0000-C000-000000000046}"

Public Const IID_IPersistStorage = _

"{0000010A-0000-0000-C000-000000000046}"

Public Const IID_IPersistStream = _

"{00000109-0000-0000-C000-000000000046}"

Public Const IID_IPersistPropertyBag = _

"{37D84F60-42CB-11CE-8135-00AA004BB851}"

Public Const INTERFACESAFE_FOR_UNTRUSTED_CALLER = &H1

Public Const INTERFACESAFE_FOR_UNTRUSTED_DATA = &H2

Public Const E_NOINTERFACE = &H80004002

Public Const E_FAIL = &H80004005

Public Const MAX_GUIDLEN = 40

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _

(pDest As Any, pSource As Any, ByVal ByteLen As Long)

Public Declare Function StringFromGUID2 Lib "ole32.dll" (rguid As _

Any, ByVal lpstrClsId As Long, ByVal cbMax As Integer) As Long

Public Type udtGUID

Data1 As Long

Data2 As Integer

Data3 As Integer

Data4(7) As Byte

End Type

Public m_fSafeForScripting As Boolean

Public m_fSafeForInitializing As Boolean

Sub Main()

m_fSafeForScripting = True

m_fSafeForInitializing = True

End Sub

在工程属性中把启动对象改成Sub Main确保上述代码会被执行。m_fSafeForScripting 和m_fSafeForInitializing两件变量的值分别指定了脚本安全和初始化安全取值。

打开控件代码窗口，在声明部分加入如下代码(如果有Option Explicit语句，当然要保证代码放在其后)：

Implements IObjectSafety

把下面两个过程代码拷贝到控件代码中：

Private Sub IObjectSafety_GetInterfaceSafetyOptions(ByVal riid As _

Long, pdwSupportedOptions As Long, pdwEnabledOptions As Long)

Dim Rc As Long

Dim rClsId As udtGUID

Dim IID As String

Dim bIID() As Byte

pdwSupportedOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER Or _

INTERFACESAFE_FOR_UNTRUSTED_DATA

If (riid <> 0) Then

CopyMemory rClsId, ByVal riid, Len(rClsId)

bIID = String$(MAX_GUIDLEN, 0)

Rc = StringFromGUID2(rClsId, VarPtr(bIID(0)), MAX_GUIDLEN)

Rc = InStr(1, bIID, vbNullChar) - 1

IID = Left$(UCase(bIID), Rc)

Select Case IID

Case IID_IDispatch

pdwEnabledOptions = IIf(m_fSafeForScripting, _

INTERFACESAFE_FOR_UNTRUSTED_CALLER, 0)

Exit Sub

Case IID_IPersistStorage, IID_IPersistStream, _

IID_IPersistPropertyBag

pdwEnabledOptions = IIf(m_fSafeForInitializing, _

INTERFACESAFE_FOR_UNTRUSTED_DATA, 0)

Exit Sub

Case Else

Err.Raise E_NOINTERFACE

Exit Sub

End Select

End If

End Sub

Private Sub IObjectSafety_SetInterfaceSafetyOptions(ByVal riid As _

Long, ByVal dwOptionsSetMask As Long, ByVal dwEnabledOptions As Long)

Dim Rc As Long

Dim rClsId As udtGUID

Dim IID As String

Dim bIID() As Byte

If (riid <> 0) Then

CopyMemory rClsId, ByVal riid, Len(rClsId)

bIID = String$(MAX_GUIDLEN, 0)

Rc = StringFromGUID2(rClsId, VarPtr(bIID(0)), MAX_GUIDLEN)

Rc = InStr(1, bIID, vbNullChar) - 1

IID = Left$(UCase(bIID), Rc)

Select Case IID

Case IID_IDispatch

If ((dwEnabledOptions And dwOptionsSetMask) <> _

INTERFACESAFE_FOR_UNTRUSTED_CALLER) Then

Err.Raise E_FAIL

Exit Sub

Else

If Not m_fSafeForScripting Then

Err.Raise E_FAIL

End If

Exit Sub

End If

Case IID_IPersistStorage, IID_IPersistStream, _

IID_IPersistPropertyBag

If ((dwEnabledOptions And dwOptionsSetMask) <> _

INTERFACESAFE_FOR_UNTRUSTED_DATA) Then

Err.Raise E_FAIL

Exit Sub

Else

If Not m_fSafeForInitializing Then

Err.Raise E_FAIL

End If

Exit Sub

End If

Case Else

Err.Raise E_NOINTERFACE

Exit Sub

End Select

End If

End Sub

保存后，把工程编译成OCX文件。现在控件已经实现了IObjectSafety 接口。在.htm中加入这件控件试一试吧。