[英]Classic ASP using C# .net DLL Object doesn't support this property or method
[英]Call .Net C# DLL method from Classic ASP
我正在處理一個經典的ASP項目,該項目需要將字符串發送到DLL,DLL將對其進行序列化並發送到Zebra熱敏打印機。
我已經構建了我的DLL,並使用regasm和/ codebase對其進行了注冊,使IIS能夠識別它。
Althougt我可以使用Server.CreateObject(“ MyDLL”)設置對象而不會出錯,嘗試訪問其中的C#方法時遇到麻煩。
DLL的C#代碼編寫如下:
using System;
using System.Runtime.InteropServices;
using System.IO;
//[assembly: ComVisible(true)]
//[assembly: Guid("6c87161d-1e02-40ef-8512-82f30bc1ae3e")]
namespace PrintZebra
{
//[ClassInterface(ClassInterfaceType.None)]
/// <summary>
/// Classe
/// </summary>
public class RawPrinterHelper
{
// Structure and API declarions:
/// <summary>
///
/// </summary>
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class DOCINFOA
{
[MarshalAs(UnmanagedType.LPStr)] public string pDocName;
[MarshalAs(UnmanagedType.LPStr)] public string pOutputFile;
[MarshalAs(UnmanagedType.LPStr)] public string pDataType;
}
[DllImport("winspool.Drv", EntryPoint = "OpenPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);
[DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool ClosePrinter(IntPtr hPrinter);
[DllImport("winspool.Drv", EntryPoint = "StartDocPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool StartDocPrinter(IntPtr hPrinter, Int32 level, [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);
[DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool EndDocPrinter(IntPtr hPrinter);
[DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool StartPagePrinter(IntPtr hPrinter);
[DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool EndPagePrinter(IntPtr hPrinter);
[DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten);
// SendBytesToPrinter()
// When the function is given a printer name and an unmanaged array
// of bytes, the function sends those bytes to the print queue.
// Returns true on success, false on failure.
public static bool SendBytesToPrinter(string szPrinterName, IntPtr pBytes, Int32 dwCount)
{
Int32 dwError = 0, dwWritten = 0;
IntPtr hPrinter = new IntPtr(0);
DOCINFOA di = new DOCINFOA();
bool bSuccess = false; // Assume failure unless you specifically succeed.
di.pDocName = ".NET RAW Document";
di.pDataType = "RAW";
// Open the printer.
if (OpenPrinter(szPrinterName.Normalize(), out hPrinter, IntPtr.Zero))
{
// Start a document.
if (StartDocPrinter(hPrinter, 1, di))
{
// Start a page.
if (StartPagePrinter(hPrinter))
{
// Write your bytes.
bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
EndPagePrinter(hPrinter);
}
EndDocPrinter(hPrinter);
}
ClosePrinter(hPrinter);
}
// If you did not succeed, GetLastError may give more information
// about why not.
if (bSuccess == false)
{
dwError = Marshal.GetLastWin32Error();
}
return bSuccess;
}
public static bool SendFileToPrinter(string szPrinterName, string szFileName)
{
// Open the file.
FileStream fs = new FileStream(szFileName, FileMode.Open);
// Create a BinaryReader on the file.
BinaryReader br = new BinaryReader(fs);
// Dim an array of bytes big enough to hold the file's contents.
Byte[] bytes = new Byte[fs.Length];
bool bSuccess = false;
// Your unmanaged pointer.
IntPtr pUnmanagedBytes = new IntPtr(0);
int nLength;
nLength = Convert.ToInt32(fs.Length);
// Read the contents of the file into the array.
bytes = br.ReadBytes(nLength);
// Allocate some unmanaged memory for those bytes.
pUnmanagedBytes = Marshal.AllocCoTaskMem(nLength);
// Copy the managed byte array into the unmanaged array.
Marshal.Copy(bytes, 0, pUnmanagedBytes, nLength);
// Send the unmanaged bytes to the printer.
bSuccess = SendBytesToPrinter(szPrinterName, pUnmanagedBytes, nLength);
// Free the unmanaged memory that you allocated earlier.
Marshal.FreeCoTaskMem(pUnmanagedBytes);
return bSuccess;
}
public static Int32 SendStringToPrinter(string szPrinterName, string szString)
{
IntPtr pBytes;
Int32 dwCount;
// How many characters are in the string?
//dwCount = szString.Length;joao
dwCount = (szString.Length + 1) * Marshal.SystemMaxDBCSCharSize;
// Assume that the printer is expecting ANSI text, and then convert
// the string to ANSI text.
pBytes = Marshal.StringToCoTaskMemAnsi(szString);
// Send the converted ANSI string to the printer.
bool bSuccess = SendBytesToPrinter(szPrinterName, pBytes, dwCount);
Int32 dwError = 0;
if (bSuccess == false)
{
dwError = Marshal.GetLastWin32Error();
}
Marshal.FreeCoTaskMem(pBytes);
return dwError;
}
}
}
在我的ASP應用程序中,我嘗試按以下方式訪問SendStringToPrinter方法:
Dim objZebra
set objZebra = Server.CreateObject("Opus127Etiquetas.RawPrinterHelper")
objZebra.SendStringToPrinter
但是調試器說objZebra不支持SendStringToPrinter屬性或方法。
重要的是要告知所有訪問DLL的權限均已授予,並且如果我在Visual Studio 2015上啟動新的VB項目並添加我的自定義DLL作為參考,則它的工作原理就像一個魅力。
真正的問題是:可以做我正在嘗試的事情嗎?
編輯
在與一些成員討論評論后,我意識到我真正需要知道的是如何將上述C#方法從靜態更改為實例 。 如我之前所說,如果我在Windows應用程序上使用此DLL,它可以正常工作,但在ASP上卻不能。 我現在知道問題出在哪里,但我不知道如何解決。
經過大量研究和夜色,我意識到我的代碼出了什么問題。
首先,我要感謝@Lankymart和@SLaks為我指明方向。
讓我們看一下代碼:
首先,我去AssemblyInfo.cs
並更改[assembly: ComVisible(false)]
,在每個我想對COM可見的類之前,我都添加了[ComVisible(true)]
,在此MSDN文檔中可以找到它: https:// msdn.microsoft.com/en-us/library/ms182198.aspx
之后,最困難的部分出現了:將靜態方法轉換為實例方法。
但是,經過進一步研究並嘗試不遺余力,我將代碼從:
public static Int32 SendStringToPrinter(string szPrinterName, string szString)
{
...
}
public class PrintHandler
{
[MethodImpl(MethodImplOptions.NoInlining)]
public Int32 SendStringToPrinter(string text, string printerName)
{
return RawPrinterHelper.SendStringToPrinter(printerName, text);
}
}
至:
[ComVisible(true)]
public Int32 SendStringToPrinter(string szPrinterName, string szString)
{
...
}
[ComVisible(true)]
public class PrintHandler
{
RawPrinterHelper rph = new RawPrinterHelper();
[MethodImpl(MethodImplOptions.NoInlining)]
[ComVisible(true)]
public Int32 SendStringToPrinter(string text, string printerName)
{
return rph.SendStringToPrinter(printerName, text);
}
}
之后一切順利,我能夠如下調用該方法:
set objZebra = Server.CreateObject("PrintZebra.RawPrinterHelper")
objZebra.SendStringToPrinter strPrinterName, strText
而已。 希望這可以解決與我的問題幾乎相同的任何其他問題。
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