从 C# .NET 应用程序调用 Delphi DLL [英] Calling a Delphi DLL from a C# .NET application

问题描述

我在下面发布了一个更好的实现.我把这个留在这里是为了让回复有意义.

我已经进行了大量搜索，以寻找在 Delphi 中编写 DLL 的正确方法，并且能够从 C# 调用它，传递和返回字符串.许多信息不完整或不正确.经过反复试验，我找到了解决方案.

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.我怀疑它在其他版本中也能正常工作.

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

这是 Delphi 代码.请记住在项目中包含版本信息.

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.

这是 C# 代码:

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();
        }
    }
}

我希望这些信息可以帮助其他人不必像我一样把头发拉出来.

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

推荐答案

根据对我帖子的回复，我创建了一个新示例，该示例将字符串缓冲区用于返回的字符串，而不仅仅是返回 PAnsiChars.

Based on responses to my post, I have created a new example that uses string buffers for the returned strings, instead of just returning PAnsiChars.

Delphi DLL 源码:

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# 代码:

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();
        }
    }
}

这里有一个额外的类，它展示了如何动态加载 DLL(抱歉，行太长了):

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);
            }
        }
    }
}

-丹

这篇关于从 C# .NET 应用程序调用 Delphi DLL的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！