学习VB.NET Smartphone时,你可能会遇到VB.net实现Smartphone中进程启动问题,这里将介绍VB.NET Smartphone进程启动问题的解决方法,在这里拿出来和大家分享一下。开始时声明时老是将ShellExecuteEx 和CreateProcess这两个熟悉得不能再熟悉的Win32在VB 6中的声明直接粘到程序中,仅是将VB6的long改为NET的int32,结果老是报错。在网上查了N天资料,才发现原来Win CE的核心API都是在一个coredll.dll文件中,使得我差点没气死!
#T#还有一点是SHELLEXECUTEINFO结构中的lpFile这种指向字符串常量的指针由于字符的编码问题不能象在Win32编程中简单声明为String类型,所在必须声明为Intptr,这样问题就出现了,使用 ShellExecuteEx函数必须使用微软在VB.net中不直接提供的指针操作,所以我只好根据网上的资料改写了一个VB.net对内存指针的封装类,详细VB.NET Smartphone代码及解释如下(新建一个模块,将以下代码粘贴进去即可使用):
- Imports System.Runtime.InteropServices '引及Net框架中对底层操作支持的命名空间
- Public Class clsDAMSMobileMarshal '我写的内存管理类
- #Region "与内存有关的API声明"
- REM 以下是与内存有关的移动设备API
- Public Declare Function LocalAlloc Lib "coredll.dll" Alias "LocalAlloc" (ByVal wFlags As Int32, _
- ByVal wBytes As Int32) As IntPtr
- Public Declare Function LocalFree Lib "coredll.dll" Alias "LocalFree" (ByVal hMem As Int32) As Int32
- Public Declare Function LocalLock Lib "coredll.dll" Alias "LocalLock" (ByVal hMem As Int32) As Int32
- Public Declare Function LocalReAlloc Lib "coredll.dll" Alias "LocalReAlloc" (ByVal hMem As IntPtr, _
- ByVal wBytes As Int32, ByVal wFlags As Int32) As IntPtr
- #End Region
- #Region "API常量声明"
- Public Const LMEM_FIXED = 0
- Public Const LMEM_MOVEABLE = &H2
- Public Const LMEM_ZEROINIT = &H40
- Public Const LPTR = LMEM_FIXED Or LMEM_ZEROINIT
- #End Region
- Public Shared Function fnAllocHLocal(ByVal ni_i32Size As Int32) As IntPtr
- '申请本地内存,返回一个指向该内存块的指针
- Return LocalAlloc(LPTR, ni_i32Size)
- End Function
- Public Shared Function fnFreeHLocal(ByRef ni_pLocal As IntPtr) As Int32
- REM 释放指定的内存块柄
- Dim ti32FunctionReturnValue As Int32
- If ni_pLocal.Equals(IntPtr.Zero) = False Then
- ti32FunctionReturnValue = (LocalFree(ni_pLocal.ToInt32))
- If ti32FunctionReturnValue = 0 Then
- ni_pLocal = IntPtr.Zero
- End If
- End If
- Return (ti32FunctionReturnValue)
- End Function
- Public Shared Function fnReAllocHLocal(ByVal ni_pIn As IntPtr, ByVal ni_i32Size As Int32) As IntPtr
- '对指定的内存块重新定义大小
- Return LocalReAlloc(ni_pIn, ni_i32Size, LMEM_MOVEABLE)
- End Function
- Public Shared Function fnStringToHLocalUni(ByVal ni_strIn As String) As IntPtr
- '将指定的字符串复制到一个内存块中,并返回该内存块的指针,这个指针必须使用fnFreeHLocal函数释放
- Dim ti32StringBufLength As Int32
- Dim tpTempA As IntPtr
- If Not (ni_strIn Is Nothing) Then
- If ni_strIn.Length = 0 Then
- Return IntPtr.Zero
- Else
- ti32StringBufLength = (ni_strIn.Length + 1) * 2 ' 包括***一个中止字符
- tpTempA = fnAllocHLocal(ti32StringBufLength)
- If tpTempA.Equals(IntPtr.Zero) = False Then '申请内存成功
- Marshal.Copy(ni_strIn.ToCharArray, 0, tpTempA, ni_strIn.Length)
- Return tpTempA
- End If
- End If
- End If
- End Function
- End Class
- 有了这个辅助函数,以下的API调用就简单了,只需正确声明即可,以下是ShellExecuteEx及CreateProcess涵数及其结构的正确声明(同样是将代码粘贴到一个新建模块中即可调用):
- imports System.Runtime.InteropServices
- REM API常数声明-------------------------
- Public Const SW_SHOWNORMAL = 1
- Public Const gcNORMAL_PRIORITY_CLASS = &H20
- Public Const gcINFINITE = &HFFFF
- Public Const WAIT_TIMEOUT = &H102&
- #Region "Structure SHELLEXECUTEINFO"
- <StructLayout(LayoutKind.Sequential)> _
- Structure SHELLEXECUTEINFO
- Public cbSize As Int32
- Public fMask As Int32
- Public hwnd As IntPtr
- Public lpVerb As IntPtr 'LPCTSTR,这种类型不能声明为string,只可以老老实实声明为Intptr
- Public lpFile As IntPtr 'LPCTSTR,这种类型不能声明为string,只可以老老实实声明为Intptr
- Public lpParameters As IntPtr 'LPCTSTR,这种类型不能声明为string,只可以老老实实声明为Intptr
- Public lpDirectory As IntPtr 'LPCTSTR,这种类型不能声明为string,只可以老老实实声明为Intptr
- Public nShow As Int32
- Public hInstApp As IntPtr
- 'Optional members
- Public lpIDList As IntPtr 'LPVOID
- Public lpClass As IntPtr 'LPCTSTR
- Public hkeyClass As Int32
- Public dwHotKey As Int32
- Public hIcon As Int32
- Public hProcess As IntPtr
- Public Sub Dispose()
- '在调用后释放结构中的内存块
- clsDAMSMobileMarshal.fnFreeHLocal(Me.lpVerb)
- clsDAMSMobileMarshal.fnFreeHLocal(Me.lpFile)
- clsDAMSMobileMarshal.fnFreeHLocal(Me.lpParameters)
- clsDAMSMobileMarshal.fnFreeHLocal(Me.lpDirectory)
- End Sub
- End Structure
- #End Region
- #Region "Structure STARTUPINFO"
- <StructLayout(LayoutKind.Sequential)> _
- Public Structure STARTUPINFO
- Public cb As Int32
- Public lpReserved As IntPtr
- Public lpDesktop As IntPtr
- Public lpTitle As IntPtr
- Public dwX As Int32
- Public dwY As Int32
- Public dwXSize As Int32
- Public dwYSize As Int32
- Public dwXCountChars As Int32
- Public dwYCountChars As Int32
- Public dwFillAttribute As Int32
- Public dwFlags As Int32
- Public wShowWindow As Int16
- Public cbReserved2 As Int16
- Public lpReserved2 As Int32
- Public hStdInput As Int32
- Public hStdOutput As Int32
- Public hStdError As Int32
- End Structure
- #End Region
- #Region "Structure PROCESS_INFORMATION"
- <StructLayout(LayoutKind.Sequential)> _
- Public Structure PROCESS_INFORMATION
- Public hProcess As IntPtr
- Public hThread As IntPtr
- Public dwProcessId As Int32
- Public dwThreadId As Int32
- End Structure
- #End Region
- REM api函数声明
- #Region "Function CreateProcess"
- public Overloads Declare Function CreateProcess Lib "coredll.dll" (ByVal imageName As String, _
- ByVal cmdLine As String, _
- ByVal lpProcessAttributes As IntPtr, _
- ByVal lpThreadAttributes As IntPtr, _
- ByVal boolInheritHandles As Int32, _
- ByVal dwCreationFlags As Int32, _
- ByVal lpEnvironment As IntPtr, _
- ByVal lpszCurrentDir As IntPtr, _
- ByRef si As STARTUPINFO, _
- ByRef pi As PROCESS_INFORMATION _
- ) As Integer
- #End Region
- #Region "Function CloseHandle"
- Public Declare Function CloseHandle Lib "CoreDll.dll" (ByVal Handle As IntPtr) As Int32
- #End Region
- #Region "Function WaitForSingleObjectEx"
- Public Declare Function WaitForSingleObjectEx Lib "coredll.dll" (ByVal hHandle As IntPtr, _
- ByVal dwMilliseconds As Int32, _
- ByVal bAlertable As Int32 _
- ) As Int32
- #End Region
- #Region "Function ShellExecuteEx"
- Public Declare Function ShellExecuteEx Lib "coredll