从C＃.NET应用程序中调用一个Delphi的DLL

本文介绍了从C＃.NET应用程序中调用一个Delphi的DLL的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

编辑：我已经发布了一个更好的实现这一点，如下。我离开这个在这里，所以响应才有意义。

我已经写一个DLL在Delphi中，并能够从C＃调用它，传递和返回字符串做了许多搜索正确的方法。大量的信息是不完整或不正确。经过多次反复试验，我找到了解决办法。

I've done numerous searches for the correct method for writing a DLL in Delp and being able to call it from C#, passing and returning strings. A lot of the information was incomplete or incorrect. After much trial and error, I found the solution.

这是使用Delphi 2007和VS 2010编译的，我怀疑它会正常工作在其他版本中也是如此。

This was compiled using Delphi 2007 and VS 2010. I suspect it will work fine in other versions as well.

下面是德尔福code。记住要在项目中包含的版本信息。

Here's the Delphi code. Remember to include version information in the project.

library DelphiLibrary; uses SysUtils; // Compiled using Delphi 2007. // NOTE: If your project doesn't have version information included, you may // receive the error "The "ResolveManifestFiles" task failed unexpectedly" // when compiling the C# application. {$R *.res} // Example function takes an input integer and input string, and returns // inputInt + 1, and inputString + ' ' + IntToStr(outputInt) as output // parameters. If successful, the return result is nil (null), otherwise it is // the exception message string. // NOTE: I've posted a better version of this below. You should use that instead. function DelphiFunction(inputInt : integer; inputString : PAnsiChar; out outputInt : integer; out outputString : PAnsiChar) : PAnsiChar; stdcall; export; var s : string; begin outputInt := 0; outputString := nil; try outputInt := inputInt + 1; s := inputString + ' ' + IntToStr(outputInt); outputString := PAnsiChar(s); Result := nil; except on e : exception do Result := PAnsiChar(e.Message); end; end; // I would have thought having "export" at the end of the function declartion // (above) would have been enough to export the function, but I couldn't get it // to work without this line also. exports DelphiFunction; begin end.

下面是C＃code：

Here's the C# code:

using System; using System.Runtime.InteropServices; namespace CsharpApp { class Program { // I added DelphiLibrary.dll to my project (NOT in References, but // "Add existing file"). In Properties for the dll, I set "BuildAction" // to None, and "Copy to Output Directory" to "Copy always". // Make sure your Delphi dll has version information included. [DllImport("DelphiLibrary.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi)] public static extern string DelphiFunction(int inputInt, string inputString, out int outputInt, out string outputString); static void Main(string[] args) { int inputInt = 1; string inputString = "This is a test"; int outputInt; string outputString; // NOTE: I've posted a better version of this below. You should use that instead. Console.WriteLine("inputInt = {0}, intputString = \"{1}\"", inputInt, inputString); var errorString = DelphiFunction(inputInt, inputString, out outputInt, out outputString); if (errorString != null) Console.WriteLine("Error = \"{0}\"", errorString); else Console.WriteLine("outputInt = {0}, outputString = \"{1}\"", outputInt, outputString); Console.Write("Press Enter:"); Console.ReadLine(); } } }

我希望这个信息可以帮助别人不一定要拉自己的头发和我一样多。

I hope this information helps someone else to not have to pull their hair out as much as I did.

推荐答案

根据答复我的文章（和一个大的谢谢那些谁指出了存在的问题），我已经创建了一个使用字符串缓冲区的一个新范例返回的字符串，而不是只返回PAnsiChars。

Based on responses to my post (and a big THANK YOU to those who pointed out the problems), I have created a new example that uses string buffers for the returned strings, instead of just returning PAnsiChars.

Delphi的DLL源：

Delphi DLL source:

library DelphiLibrary; uses SysUtils; // Compiled using Delphi 2007. // NOTE: If your project doesn't have version information included, you may // receive the error "The "ResolveManifestFiles" task failed unexpectedly" // when compiling the C# application. {$R *.res} // A note on returing strings. I had originally written this so that the // output string was just a PAnsiChar. But several people pointed out that // since Delphi strings are reference-counted, this was a bad idea since the // memory for the string could get overwritten before it was used. // // Because of this, I re-wrote the example so that you have to pass a buffer for // the result strings. I saw some examples of how to do this, where they // returned the actual string length also. This isn't necessary, because the // string is null-terminated, and in fact the examples themselves never used the // returned string length. // Example function takes an input integer and input string, and returns // inputInt + 1, and inputString + ' ' + IntToStr(outputInt). If successful, // the return result is true, otherwise errorMsgBuffer contains the the // exception message string. function DelphiFunction(inputInt : integer; inputString : PAnsiChar; out outputInt : integer; outputStringBufferSize : integer; var outputStringBuffer : PAnsiChar; errorMsgBufferSize : integer; var errorMsgBuffer : PAnsiChar) : WordBool; stdcall; export; var s : string; begin outputInt := 0; try outputInt := inputInt + 1; s := inputString + ' ' + IntToStr(outputInt); StrLCopy(outputStringBuffer, PAnsiChar(s), outputStringBufferSize-1); errorMsgBuffer[0] := #0; Result := true; except on e : exception do begin StrLCopy(errorMsgBuffer, PAnsiChar(e.Message), errorMsgBufferSize-1); Result := false; end; end; end; // I would have thought having "export" at the end of the function declartion // (above) would have been enough to export the function, but I couldn't get it // to work without this line also. exports DelphiFunction; begin end.

C＃code：

C# Code:

using System; using System.Runtime.InteropServices; namespace CsharpApp { class Program { // I added DelphiLibrary.dll to my project (NOT in References, but // "Add existing file"). In Properties for the dll, I set "BuildAction" // to None, and "Copy to Output Directory" to "Copy always". // Make sure your Delphi dll has version information included. [DllImport("DelphiLibrary.dll", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi)] public static extern bool DelphiFunction(int inputInt, string inputString, out int outputInt, int outputStringBufferSize, ref string outputStringBuffer, int errorMsgBufferSize, ref string errorMsgBuffer); static void Main(string[] args) { int inputInt = 1; string inputString = "This is a test"; int outputInt; const int stringBufferSize = 1024; var outputStringBuffer = new String('\x00', stringBufferSize); var errorMsgBuffer = new String('\x00', stringBufferSize); if (!DelphiFunction(inputInt, inputString, out outputInt, stringBufferSize, ref outputStringBuffer, stringBufferSize, ref errorMsgBuffer)) Console.WriteLine("Error = \"{0}\"", errorMsgBuffer); else Console.WriteLine("outputInt = {0}, outputString = \"{1}\"", outputInt, outputStringBuffer); Console.Write("Press Enter:"); Console.ReadLine(); } } }

这是一个额外的类，它展示了如何动态地加载DLL（对不起排长队）：

And here's an additional class that shows how to load the DLL dynamically (sorry for the long lines):

using System; using System.Runtime.InteropServices; namespace CsharpApp { static class DynamicLinking { [DllImport("kernel32.dll", EntryPoint = "LoadLibrary")] static extern int LoadLibrary([MarshalAs(UnmanagedType.LPStr)] string lpLibFileName); [DllImport("kernel32.dll", EntryPoint = "GetProcAddress")] static extern IntPtr GetProcAddress(int hModule, [MarshalAs(UnmanagedType.LPStr)] string lpProcName); [DllImport("kernel32.dll", EntryPoint = "FreeLibrary")] static extern bool FreeLibrary(int hModule); [UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)] delegate bool DelphiFunction(int inputInt, string inputString, out int outputInt, int outputStringBufferSize, ref string outputStringBuffer, int errorMsgBufferSize, ref string errorMsgBuffer); public static void CallDelphiFunction(int inputInt, string inputString, out int outputInt, out string outputString) { const string dllName = "DelphiLib.dll"; const string functionName = "DelphiFunction"; int libHandle = LoadLibrary(dllName); if (libHandle == 0) throw new Exception(string.Format("Could not load library \"{0}\"", dllName)); try { var delphiFunctionAddress = GetProcAddress(libHandle, functionName); if (delphiFunctionAddress == IntPtr.Zero) throw new Exception(string.Format("Can't find function \"{0}\" in library \"{1}\"", functionName, dllName)); var delphiFunction = (DelphiFunction)Marshal.GetDelegateForFunctionPointer(delphiFunctionAddress, typeof(DelphiFunction)); const int stringBufferSize = 1024; var outputStringBuffer = new String('\x00', stringBufferSize); var errorMsgBuffer = new String('\x00', stringBufferSize); if (!delphiFunction(inputInt, inputString, out outputInt, stringBufferSize, ref outputStringBuffer, stringBufferSize, ref errorMsgBuffer)) throw new Exception(errorMsgBuffer); outputString = outputStringBuffer; } finally { FreeLibrary(libHandle); } } } }

-Dan

-Dan