vb.net Dynamic Call API

ImportsSystemImportsSystem.Runtime.InteropServices Public ClassDllinvoke Public Sub New(ByValDllPath as String)        Me. Hlib =dllinvoke.loadlibrary (DllPath)End Sub    Protected Overrides SubFinalize ()TryDllinvoke.freelibrary (Me. Hlib)Finally            MyBase. Finalize ()End Try    End Sub<dllimport ("Kernel32.dll") > _    Private Shared FunctionFreeLibrary (ByVal[Lib] asINTPTR) as Boolean    End Function<dllimport ("Kernel32.dll") > _    Private Shared FunctionGetProcAddress (ByVal[Lib] asINTPTR,ByValFuncName as String) asIntPtrEnd Function     Public FunctionInvoke (ByValApiname as String,ByValT asType) as[Delegate]        ReturnMarshal.getdelegateforfunctionpointer (Dllinvoke.getprocaddress (Me. Hlib, Apiname), T)End Function<dllimport ("Kernel32.dll") > _    Private Shared FunctionLoadLibrary (ByValPath as String) asIntPtrEnd Function    PrivateHlib asIntPtrEnd Class

ImportsSystemImportsSystem.Runtime.CompilerServicesImportsSystem.Runtime.InteropServicesImportsSystem.Text Public ClassTestPrivate Declare FunctionMessageBoxALib "User32" Alias "MessageBoxA"(ByValhwnd as Integer,ByValLptext asStringBuilder,ByValLpcaption asStringBuilder,ByValWtype as Integer) as Long    Private Delegate FunctionMessageboxadelegate (ByValhwnd as Integer,ByValLptext asStringBuilder,ByValLpcaption asStringBuilder,ByValWtype as Integer) as Long     Public Shared SubMain ()DimInvoke as NewDllinvoke ("user32.dll")        DimMode asMessageboxadelegate =DirectCast(Invoke. Invoke ("MessageBoxA",GetType(Messageboxadelegate)), messageboxadelegate) mode. Invoke (0,NewStringBuilder ("haha"),NewStringBuilder ("title"),0) Console.WriteLine ("OK") Console.ReadLine ()End SubEnd Class