35、服务管理实用工具开发详解

服务管理实用工具开发详解

在服务管理的开发中，我们常常需要实现对服务状态的查询、启动、停止和恢复等操作。下面将详细介绍如何开发一个实用工具来完成这些任务。

1. 关键方法与结构

1.1 OpenService 方法

该方法用于打开一个服务并返回服务对象。代码如下：

' Open a service and return the service object 
Public Function OpenService(Svc As ServiceStatus, rights As _ 
ServiceAccessRights) As ServiceObject 
    Dim hnd& 
    Dim newservice As New ServiceObject 

    ' Service manager must be open to perform this operation 
    If schandle = 0 Then Exit Function 
    hnd = intOpenService(schandle, Svc.Name, rights Or SERVICE_QUERY_STATUS) 
    If hnd <> 0 Then 
        ' Initialize the service via a Friend function 
        Call newservice.Initialize(hnd,  Svc.Name, Svc.DisplayName) 
        Set OpenService = newservice 
    End If 
End Function

1.2 EnumServicesStatus 函数

此函数用于检索包含 ServiceStatus 对象的集合，是较为复杂的一个函数。它涉及到 ENUM_SERVICE_STATUS 和 SERVICE_STATUS 两个结构。

C 语言中的结构声明 ：

typedef struct _ENUM_SERVICE_STATUS { // ess 
    LPTSTR lpServiceName; 
    LPTSTR lpDisplayName; 
    SERVICE_STATUS ServiceStatus; 
} ENUM_SERVICE_STATUS, *LPENUM_SERVICE_STATUS; 

typedef struct _SERVICE_STATUS { // ss 
    DWORD dwServiceType; 
    DWORD dwCurrentState; 
    DWORD dwControlsAccepted; 
    DWORD dwWin32ExitCode;
    DWORD dwServiceSpecificExitCode; 
    DWORD dwCheckPoint; 
    DWORD dwWaitHint; 
} SERVICE_STATUS, *LPSERVICE_STATUS;

Visual Basic 中的结构声明 ：

Public Type ENUM_SERVICE_STATUS 
    lpServiceName As Long 
    lpDisplayName As Long 
    Status As SERVICE_STATUS 
End Type 

' Service structures 
Public Type SERVICE_STATUS 
    dwServiceType As Long 
    dwCurrentState As Long 
    dwControlsAccepted As Long 
    dwWin32ExitCode As Long 
    dwServiceSpecificExitCode As Long 
    dwCheckPoint As Long 
    dwWaitHint As Long 
End Type

EnumServicesStatus 函数的代码如下：

' Retrieve a collection containing ServiceStatus objects 
Public Function EnumServicesStatus() As Collection 
    Dim res& 
    Dim lpServices As Long 
    Dim BytesNeeded As Long 
    Dim ServicesReturned As Long 
    Dim ResumeHandle As Long 
    Dim Buffer() As Byte 
    ReDim Buffer(512) 
    Dim x& 
    Dim CurrentOffset& 
    Dim c As New Collection 
    Dim s As ServiceStatus 
    Dim continue As Boolean 

    Do 
        ' Load the buffer with as many services as possible 
        ' We exclude driver services for now 
        res = intEnumServicesStatus(schandle, &H30, 3, VarPtr(Buffer(0)), _ 
        UBound(Buffer()), BytesNeeded, ServicesReturned, ResumeHandle) 
        If res = 0 And Err.LastDllError = ERROR_MORE DATA Then 
            ' Buffer couldn't hold all the services 
            continue = True 
        Else 
            continue = False 
        End If 
        For x = 1 To ServicesReturned 
            Set s = New ServiceStatus 
            ' The ServiceStatus buffer does the actual extraction 
            Call s.ParseServiceInfo(Buffer(), CurrentOffset) 
            c.Add s 
            ' 36 is the size of the ENUM_SERVICE_STATUS structure 
            CurrentOffset = CurrentOffset + 36 
        Next x 
        If continue Then 
            ' Prepare for the next call 
            CurrentOffset = 0 
            ReDim Buffer(BytesNeeded) 
        End If 
    Loop While continue 
    Set EnumServicesStatus = c 
End Function

2. 服务状态类

ServiceStatus 类用于存储服务的最新状态信息。它有两种初始化方式：一种是解析 EnumServicesStatus 函数创建的缓冲区；另一种是使用 InternalInitialize 函数直接设置私有信息。

' Holds the latest value of each 
Private Status As SERVICE_STATUS 
Private SvcName As String 
Private intDisplayName As String 

' Used by the internal objects to initialize a new ServiceStatus object 
' that is not created via an enumeration. 
Friend Sub Internallnitialize(pName As String, pDisplay As String, _ 
stat As SERVICE_STATUS) 
    intDisplayName = pDisplay 
    SvcName = pName 
    LSet Status = stat 
End Sub

' Extracts the private information from the buffer. Data is assumed 
' to start at the specified offset 
' Always returns 0 
Friend Function ParseServiceInfo(Buffer() As Byte, ByVal Offset As Long) _ 
As Long 
    Dim svcstat As ENUM_SERVICE_STATUS 
    ' Copy the service structure 
    Call RtlMoveMemory(VarPtr(svcstat), VarPtr(Buffer(Offset)), Len(svcstat)) 
    ' Extract the names 
    SvcName = GetVBStringFromAddress(svcstat.lpServiceName) 
    intDisplayName = GetVBStringFromAddress(svcstat.lpDisplayName) 
    ' Store the SERVICE_STATUS portion only 
    LSet Status = svcstat.Status
End Function 

' Get a VB string from an address 
Public Function GetVBStringFromAddress(ByVal addr&) As String 
    Dim uselen& 
    Dim res$ 
    If addr = 0 Then Exit Function 
    uselen = lstrlen(addr) 
    res$ = String$(uselen + 1, 0) 
    Call lstrcpy(res, addr) 
    GetVBStringFromAddress = Left$(res$, uselen) 
End Function

3. 服务对象类

ServiceObject 类相对简单，它内部存储服务句柄、服务名称和显示名称，并提供了停止、启动和查询服务状态的方法。

' Service Object Class 
' Copyright © 1998 by Desaware Inc. All Rights Reserved 

' This object represents an open service 

Option Explicit 

Private intServiceHandle As Long 
Private intServiceName As String 
Private intDisplayName As String 

' For convenience, this object is initialized by the ServiceManager 
' with both the name and display name 
Friend Sub Initialize(ByVal hnd As Long, Name As String, _ 
DisplayName As String) 
    intServiceHandle = hnd 
    intServiceName = Name 
    intDisplayName = DisplayName 
End Sub 

' Get the short name 
Property Get ServiceName() As String 
    ServiceName = intServiceName
End Property 

' Get the current status 
Property Get QueryServiceStatus() As ServiceStatus 
    Dim stat As SERVICE_STATUS 
    Dim res& 
    Dim sres As New ServiceStatus 
    res = intQueryServiceStatus(intServiceHandle, stat) 
    If res <> 0 Then 
        ' Another way to get a ServiceStatus object 
        Call sres.InternalInitialize(intServiceName, intDisplayName, stat) 
        Set QueryServiceStatus = sres 
    End If 
End Property 

' Perform Stop, Pause, Continue and Interrogate 
Public Function ServiceControl(Operation As ServiceControlConstants) As Long 
    Dim stat As SERVICE_STATUS 
    Dim res& 
    res = intControlService(intServiceHandle, Operation, stat) 
    ServiceControl = res 
End Function 

' Perform start 
Public Function StartService() 
    Dim res& 
    res = intStartService(intServiceHandle, 0, 0) 
    StartService = res 
End Function 

' Close the handle on termination 
Private Sub Class_Terminate() 
    If intServiceHandle <> 0 Then 
        Call CloseServiceHandle(intServiceHandle) 
    End If 
End Sub

4. 实用工具的开发

4.1 工具功能概述

该实用工具的目标是创建一个可以轻松停止并重新启动 Internet Information Services 的工具，以便替换 Active Server Page 调用的 DLL。它具有以下功能：
- 一个列表框，用于显示每个服务的名称和显示名称，支持多选。
- 启动和停止一个或多个服务的按钮。
- 一个按钮，用于将所有服务恢复到程序启动时的原始状态。
- 一种跟踪更改的方式，以便在程序关闭时提示是否将服务恢复到原始状态。
- 一个按钮，用于选择 IIS 服务。

4.2 变量定义

Dim sc As New ServiceManager 

Dim ServiceCollection As Collection ' Hold current states 
Dim OriginalStates As Collection    ' Record original states
' Collection of ServiceObject objects that are currently 
' being changed 
Dim ChangesInProgress As Collection 

Dim Changed As Boolean  ' Mark true if any state change has been caused 
Dim unloadpending As Boolean    ' Mark true if final restore operation 

' 0 to restore 
Dim TargetState As ServiceStateConstants

4.3 表单加载事件

Private Sub Form_Load() 
    Dim res& 
    ' Open the ServiceManager 
    res = sc.OpenSCManager("", "", SC_MANAGER_ENUMERATE_SERVICE _ 
    Or SC_MANAGER_CONNECT) 
    ' Update the ServiceCollection and display the services 
    LoadList True 
    Set OriginalStates = ServiceCollection 
    ' We don't want to hold two references to the collection 
    Set ServiceCollection = Nothing 
End Sub

4.4 加载服务列表函数

' Loads the ServiceCollection collection with a list of all services 
' Optionally displays them 
Private Sub LoadList(bDisplay As Boolean) 
    Dim res& 
    Dim svcstat As ServiceStatus 
    lstServices.Refresh 
    Set ServiceCollection = sc.EnumServicesStatus() 
    If bDisplay Then 
        For Each svcstat In ServiceCollection 
            lstServices.AddItem svcstat.Name & ":   " & svcstat.DisplayName 
        Next 
    End If
End Sub

4.5 启用或禁用用户界面函数

' Enables or disables the user interface of the application. 
' Also controls the mouse pointer and timer. 
' The UI must be disabled while service start or stop is in progress 
Private Function EnablePanel(ByVal bEnabled As Boolean) 
    cmdStop.Enabled = bEnabled 
    cmdStart.Enabled = bEnabled 
    cmdRestore.Enabled = bEnabled 
    lstServices.Enabled = bEnabled 
    If Not bEnabled Then 
        Screen.MousePointer = vbHourglass 
        Timeri.Enabled = True 
    Else 
        Screen.MousePointer = vbNormal 
        Timer1.Enabled = False 
    End If 

End Function

4.6 打开选定服务函数

' Loads the ChangesInProgress collection with the 
' ServiceObject objects for the selected services 
Private Function OpenSelectedServices() 
    Dim index& 
    Dim currententry$ 
    Dim svcstat As ServiceStatus 
    Call LoadList(False) 
    Set ChangesInProgress = New Collection
    For index = 0 To lstServices.ListCount - 1 
        If lstServices.Selected(index) Then 
            currententry = lstServices.List(index) 
            For Each svcstat In ServiceCollection 
                ' Match based on the service name 
                If InStr(currententry, svcstat.Name & ":") = 1 Then 
                    ChangesInProgress.Add sc.OpenService(svcstat, _ 
                    SERVICE_START Or SERVICE_STOP), svcstat.Name 
                    Exit For 
                End If 
            Next 
        End If 
    Next index 
End Function

5. 服务操作代码

5.1 停止选定服务

' Stops the selected services 
Private Sub cmdStop_Click() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim starttimer As Boolean 
    Dim RemoveThis As Boolean 
    Dim res& 
    Call OpenSelectedServices 
    For Each so In ChangesInProgress 
        Set stat = so.QueryServiceStatus 
        If stat.CurrentState <> SERVICE_STOPPED Then 
            res = so.ServiceControl(SERVICE_CONTROL_STOP) 
            If res <> 0 Then 
                starttimer = True 
            Else 
                RemoveThis = True 
            End If 
        Else 
            RemoveThis = True 
        End If 
        If RemoveThis Then ChangesInProgress.Remove stat.Name
        RemoveThis = False 
    Next so 
    If starttimer Then 
        EnablePanel False 
        TargetState = SERVICE_STOPPED 
        Changed = True 
    Else 
        Set ChangesInProgress = Nothing 
    End If 
End Sub 

5.2 启动选定服务

' Starts the selected services 
Private Sub cmdStart_Click() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim starttimer As Boolean 
    Dim RemoveThis As Boolean 
    Dim res& 
    Call OpenSelectedServices 
    For Each so In ChangesInProgress 
        Set stat = so.QueryServiceStatus 
        If stat.CurrentState <> SERVICE_RUNNING Then 
            res = so.StartService 
            If res <>  Then 
                starttimer = True 
            Else 
                RemoveThis = True 
            End If 
        Else 
            RemoveThis = True 
        End If 
        If RemoveThis Then ChangesInProgress.Remove stat.Name 
        RemoveThis = False 
    Next so 
    If starttimer Then 
        EnablePanel False 
        TargetState = SERVICE_RUNNING 
        Changed = True 
    Else 
        Set ChangesInProgress = Nothing 
    End If 
End Sub

5.3 恢复服务到原始状态

' Restores services to their original state 
Private Sub cmdRestore_Click() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim starttimer As Boolean 
    Dim orig As ServiceStateConstants 
    Dim res& 
    Call LoadList(False) 
    Set ChangesInProgress = New Collection 
    For Each stat In ServiceCollection 
        If stat.CurrentState <> OriginalState(stat.Name) Then 
            ChangesInProgress.Add sc.OpenService(stat, SERVICE_START _ 
            Or SERVICE_STOP), stat.Name 
        End If 
    Next 
    For Each so In ChangesInProgress 
        orig = OriginalState(so.ServiceName) 
        If orig = SERVICE_RUNNING Then 
            res = so.StartService 
        Else 
            res = so.ServiceControl(SERVICE_CONTROL_STOP) 
        End If 
        If res <> 0 Then 
            starttimer = True 
        Else 
ChangesInProgress.Remove so.ServiceName 
        End If 
    Next so 
    If starttimer Then 
        EnablePanel False 
        TargetState = 0 
        Changed = True 
    Else 
        Set ChangesInProgress = Nothing 
    End If 
End Sub

6. 程序关闭与定时器处理

6.1 表单卸载事件

Private Sub Form_Unload(Cancel As Integer) 
    Dim res& 
    If Changed Then 
        ' If any change has been made, give the user 
        ' the option to restore 
        res = MsgBox("Changes have been made - Restore service states?", _ 
        vbYesNo, "Exit confirmation") 
        If res = vbYes Then 
            unloadpending = True 
            Me.Hide ' Hide the form - no reason to clutter the screen 
            cmdRestore_Click 
            Cancel = -1 
            Changed = False 
            Exit Sub 
        End If 
    End If 

    Set ServiceCollection = Nothing 
    Set OriginalStates = Nothing 
    Set ChangesInProgress = Nothing 
    Set sc = Nothing 
End Sub

6.2 定时器事件

' Poll for the completion of the operation in progress 
Private Sub Timer1_Timer() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim target As Long 
    For Each so In ChangesInProgress 
        Set stat = so.QueryServiceStatus 
        ' Zero is the restore condition 
        If TargetState = 0 Then 
            target = OriginalState(stat.Name) 
        Else 
            target = TargetState 
        End If 

        If stat.CurrentState = target Then
            ' 服务进入目标状态，移除对象
        End If
    Next
    ' 集合为空时，重新启用用户界面
End Sub

总结

通过以上步骤，我们完成了一个服务管理实用工具的开发。该工具可以方便地对服务进行启动、停止和恢复操作，并且能够跟踪服务状态的变化。在开发过程中，我们使用了多个类和函数，涉及到服务状态的查询、解析和控制等操作。通过合理的设计和代码实现，我们可以有效地管理系统中的服务。

下面是一个简单的流程图，展示了服务操作的基本流程：

graph TD;
    A[开始] --> B[打开服务管理器];
    B --> C[加载服务列表];
    C --> D{选择操作};
    D -- 停止服务 --> E[打开选定服务];
    D -- 启动服务 --> E;
    D -- 恢复服务 --> F[对比当前状态与原始状态];
    F --> E;
    E --> G[执行操作];
    G --> H{操作完成?};
    H -- 是 --> I[移除已完成服务];
    I --> J{所有服务完成?};
    J -- 是 --> K[重新启用界面];
    J -- 否 --> G;
    H -- 否 --> G;
    K --> L[结束];

同时，我们还可以用表格总结一下关键类和方法的功能：
| 类/方法 | 功能 |
| ---- | ---- |
| OpenService | 打开一个服务并返回服务对象 |
| EnumServicesStatus | 检索包含 ServiceStatus 对象的集合 |
| ServiceStatus | 存储服务的最新状态信息 |
| ServiceObject | 提供停止、启动和查询服务状态的方法 |
| LoadList | 加载服务列表 |
| OpenSelectedServices | 打开选定的服务 |
| cmdStop_Click | 停止选定的服务 |
| cmdStart_Click | 启动选定的服务 |
| cmdRestore_Click | 恢复服务到原始状态 |

服务管理实用工具开发详解（续）

7. 操作步骤详解

为了更好地理解如何使用这个服务管理实用工具，下面详细介绍各个操作的具体步骤。

7.1 启动服务操作步骤

1. 选择服务 ：在列表框中勾选要启动的服务。
2. 点击启动按钮 ：触发 cmdStart_Click 事件，系统会执行以下操作：
   • 调用 OpenSelectedServices 函数，该函数会先调用 LoadList 函数加载当前服务列表到 ServiceCollection 集合中，然后遍历列表框，将选中的服务对应的 ServiceObject 对象添加到 ChangesInProgress 集合。
   • 遍历 ChangesInProgress 集合，对于每个 ServiceObject 对象，调用 QueryServiceStatus 方法获取当前状态。
   • 如果服务当前状态不是 SERVICE_RUNNING ，则调用 StartService 方法启动服务。
   • 若启动成功，设置 starttimer 为 True ，调用 EnablePanel 函数禁用用户界面，设置 TargetState 为 SERVICE_RUNNING ，并标记 Changed 为 True ；若启动失败，从 ChangesInProgress 集合中移除该服务对象。

以下是启动服务的代码示例：

' Starts the selected services 
Private Sub cmdStart_Click() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim starttimer As Boolean 
    Dim RemoveThis As Boolean 
    Dim res& 
    Call OpenSelectedServices 
    For Each so In ChangesInProgress 
        Set stat = so.QueryServiceStatus 
        If stat.CurrentState <> SERVICE_RUNNING Then 
            res = so.StartService 
            If res <> 0 Then 
                starttimer = True 
            Else 
                RemoveThis = True 
            End If 
        Else 
            RemoveThis = True 
        End If 
        If RemoveThis Then ChangesInProgress.Remove stat.Name 
        RemoveThis = False 
    Next so 
    If starttimer Then 
        EnablePanel False 
        TargetState = SERVICE_RUNNING 
        Changed = True 
    Else 
        Set ChangesInProgress = Nothing 
    End If 
End Sub

7.2 停止服务操作步骤

1. 选择服务 ：在列表框中勾选要停止的服务。
2. 点击停止按钮 ：触发 cmdStop_Click 事件，系统会执行以下操作：
   • 调用 OpenSelectedServices 函数，将选中的服务对应的 ServiceObject 对象添加到 ChangesInProgress 集合。
   • 遍历 ChangesInProgress 集合，对于每个 ServiceObject 对象，调用 QueryServiceStatus 方法获取当前状态。
   • 如果服务当前状态不是 SERVICE_STOPPED ，则调用 ServiceControl 方法停止服务。
   • 若停止成功，设置 starttimer 为 True ，调用 EnablePanel 函数禁用用户界面，设置 TargetState 为 SERVICE_STOPPED ，并标记 Changed 为 True ；若停止失败，从 ChangesInProgress 集合中移除该服务对象。

以下是停止服务的代码示例：

' Stops the selected services 
Private Sub cmdStop_Click() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim starttimer As Boolean 
    Dim RemoveThis As Boolean 
    Dim res& 
    Call OpenSelectedServices 
    For Each so In ChangesInProgress 
        Set stat = so.QueryServiceStatus 
        If stat.CurrentState <> SERVICE_STOPPED Then 
            res = so.ServiceControl(SERVICE_CONTROL_STOP) 
            If res <> 0 Then 
                starttimer = True 
            Else 
                RemoveThis = True 
            End If 
        Else 
            RemoveThis = True 
        End If 
        If RemoveThis Then ChangesInProgress.Remove stat.Name
        RemoveThis = False 
    Next so 
    If starttimer Then 
        EnablePanel False 
        TargetState = SERVICE_STOPPED 
        Changed = True 
    Else 
        Set ChangesInProgress = Nothing 
    End If 
End Sub 

7.3 恢复服务到原始状态操作步骤

1. 点击恢复按钮 ：触发 cmdRestore_Click 事件，系统会执行以下操作：
   • 调用 LoadList 函数加载当前服务列表到 ServiceCollection 集合。
   • 遍历 ServiceCollection 集合，将当前状态与原始状态不同的服务对应的 ServiceObject 对象添加到 ChangesInProgress 集合。
   • 遍历 ChangesInProgress 集合，根据原始状态调用 StartService 或 ServiceControl 方法启动或停止服务。
   • 若操作成功，设置 starttimer 为 True ，调用 EnablePanel 函数禁用用户界面，设置 TargetState 为 0 ，并标记 Changed 为 True ；若操作失败，从 ChangesInProgress 集合中移除该服务对象。

以下是恢复服务到原始状态的代码示例：

' Restores services to their original state 
Private Sub cmdRestore_Click() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim starttimer As Boolean 
    Dim orig As ServiceStateConstants 
    Dim res& 
    Call LoadList(False) 
    Set ChangesInProgress = New Collection 
    For Each stat In ServiceCollection 
        If stat.CurrentState <> OriginalState(stat.Name) Then 
            ChangesInProgress.Add sc.OpenService(stat, SERVICE_START _ 
            Or SERVICE_STOP), stat.Name 
        End If 
    Next 
    For Each so In ChangesInProgress 
        orig = OriginalState(so.ServiceName) 
        If orig = SERVICE_RUNNING Then 
            res = so.StartService 
        Else 
            res = so.ServiceControl(SERVICE_CONTROL_STOP) 
        End If 
        If res <> 0 Then 
            starttimer = True 
        Else 
            ChangesInProgress.Remove so.ServiceName 
        End If 
    Next so 
    If starttimer Then 
        EnablePanel False 
        TargetState = 0 
        Changed = True 
    Else 
        Set ChangesInProgress = Nothing 
    End If 
End Sub

8. 定时器的作用

定时器 Timer1 在服务状态改变操作中起着重要作用。当服务状态改变操作开始后，用户界面会被禁用，定时器开始运行，它会定期检查 ChangesInProgress 集合中每个服务的状态。

以下是定时器事件的代码示例：

' Poll for the completion of the operation in progress 
Private Sub Timer1_Timer() 
    Dim so As ServiceObject 
    Dim stat As ServiceStatus 
    Dim target As Long 
    For Each so In ChangesInProgress 
        Set stat = so.QueryServiceStatus 
        ' Zero is the restore condition 
        If TargetState = 0 Then 
            target = OriginalState(stat.Name) 
        Else 
            target = TargetState 
        End If 

        If stat.CurrentState = target Then
            ' 服务进入目标状态，移除对象
            ChangesInProgress.Remove so.ServiceName
        End If
    Next
    ' 集合为空时，重新启用用户界面
    If ChangesInProgress.Count = 0 Then
        EnablePanel True
    End If
End Sub

定时器的操作步骤如下：
1. 遍历集合 ：遍历 ChangesInProgress 集合中的每个 ServiceObject 对象。
2. 获取状态 ：调用 QueryServiceStatus 方法获取当前服务状态。
3. 判断目标状态 ：根据 TargetState 的值确定目标状态。
4. 对比状态 ：如果当前状态等于目标状态，从 ChangesInProgress 集合中移除该服务对象。
5. 检查集合是否为空 ：如果 ChangesInProgress 集合为空，调用 EnablePanel 函数重新启用用户界面。

9. 程序关闭处理

当程序关闭时，会触发 Form_Unload 事件。如果在程序运行过程中服务状态发生了改变，会弹出提示框询问用户是否将服务恢复到原始状态。

以下是表单卸载事件的代码示例：

Private Sub Form_Unload(Cancel As Integer) 
    Dim res& 
    If Changed Then 
        ' If any change has been made, give the user 
        ' the option to restore 
        res = MsgBox("Changes have been made - Restore service states?", _ 
        vbYesNo, "Exit confirmation") 
        If res = vbYes Then 
            unloadpending = True 
            Me.Hide ' Hide the form - no reason to clutter the screen 
            cmdRestore_Click 
            Cancel = -1 
            Changed = False 
            Exit Sub 
        End If 
    End If 

    Set ServiceCollection = Nothing 
    Set OriginalStates = Nothing 
    Set ChangesInProgress = Nothing 
    Set sc = Nothing 
End Sub

程序关闭处理的操作步骤如下：
1. 检查状态改变 ：检查 Changed 变量是否为 True ，如果是，则表示服务状态发生了改变。
2. 弹出提示框 ：使用 MsgBox 函数弹出提示框，询问用户是否恢复服务状态。
3. 处理用户选择 ：
- 如果用户选择 Yes ，设置 unloadpending 为 True ，隐藏表单，调用 cmdRestore_Click 函数恢复服务状态，取消关闭操作，将 Changed 标记为 False 。
- 如果用户选择 No ，继续执行关闭操作，释放相关集合和对象。

10. 注意事项

在使用这个服务管理实用工具时，需要注意以下几点：
- 服务权限 ：确保程序具有足够的权限来执行服务的启动、停止和恢复操作。
- 状态更新 ：由于服务状态的改变可能需要一些时间，因此在操作过程中要耐心等待，避免频繁操作。
- 资源释放 ：在程序关闭时，要确保释放所有占用的资源，避免内存泄漏。

总结与展望

通过以上详细的开发过程和操作步骤，我们成功开发了一个功能完善的服务管理实用工具。该工具可以方便地对系统中的服务进行启动、停止和恢复操作，并且能够跟踪服务状态的变化。

在未来的开发中，我们可以进一步优化这个工具，例如添加更多的服务操作功能，如暂停、继续服务等；或者改进用户界面，提高用户体验。同时，我们还可以考虑将该工具集成到其他系统中，实现更复杂的服务管理需求。

下面是一个流程图，展示了程序关闭时的处理流程：

graph TD;
    A[程序关闭] --> B{服务状态改变?};
    B -- 是 --> C[弹出提示框];
    C -- 恢复 --> D[恢复服务状态];
    C -- 不恢复 --> E[释放资源];
    B -- 否 --> E;
    D --> E;
    E --> F[结束];

另外，我们再用表格总结一下服务操作的关键步骤：
| 操作 | 关键步骤 |
| ---- | ---- |
| 启动服务 | 选择服务 -> 点击启动按钮 -> 打开选定服务 -> 执行启动操作 -> 定时器检查状态 -> 完成后重新启用界面 |
| 停止服务 | 选择服务 -> 点击停止按钮 -> 打开选定服务 -> 执行停止操作 -> 定时器检查状态 -> 完成后重新启用界面 |
| 恢复服务 | 点击恢复按钮 -> 对比状态 -> 打开选定服务 -> 执行操作 -> 定时器检查状态 -> 完成后重新启用界面 |
| 程序关闭 | 检查状态改变 -> 弹出提示框 -> 处理用户选择 -> 释放资源 |