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C#調(diào)用C++ 鏈接庫(kù)的方式分為靜態(tài)調(diào)用和動(dòng)態(tài)調(diào)用這兩種方式。靜態(tài)調(diào)用之前的文章里面都有介紹，使用.net 提供的DllImport 導(dǎo)入相關(guān)的C++ 庫(kù)即可。請(qǐng)看之前的文章，https://www.cnblogs.com/zhangweizhong/p/8119340.html 。
原理LoadLibrary ( string lpFileName)：載入指定的動(dòng)態(tài)鏈接庫(kù)，并將它映射到當(dāng)前進(jìn)程使用的地址空間。載入成功后即可訪問(wèn)庫(kù)內(nèi)保存的資源 ， 除了LoadLibrary 方法，還有一個(gè)類(lèi)似的 LoadLibraryEx 方法。 GetProcAddress (int hModule, string lpProcName)：GetProcAddress函數(shù)檢索指定的動(dòng)態(tài)鏈接庫(kù)(DLL)中的輸出庫(kù)函數(shù)地址。 如果函數(shù)調(diào)用成功，返回值是DLL中的輸出函數(shù)地址。 如果函數(shù)調(diào)用失敗，返回值是NULL。調(diào)用函數(shù)GetLastError ，得到具體的錯(cuò)誤信息。
FreeLibrary ( int hModule) ：釋放指定的動(dòng)態(tài)鏈接庫(kù)，它們?cè)缦仁怯肔oadLibrary API函數(shù)裝載的。
GetLastError() ： 獲取錯(cuò)誤信息
實(shí)現(xiàn)
1. 將kernel32中的幾個(gè)方法封裝成本地調(diào)用類(lèi) DLLWrapper  using System; using System.IO; using System.Runtime.InteropServices; namespace Irisking.Basic.Util { /// <summary> /// DLLWrapper /// </summary> internal class DLLWrapper { [DllImport("kernel32.dll")] private static extern uint GetLastError(); /// <summary> /// API LoadLibraryEx /// </summary> /// <param name="lpFileName"></param> /// <param name="hReservedNull"></param> /// <param name="dwFlags"></param> /// <returns></returns> [DllImport("kernel32.dll", EntryPoint = "LoadLibraryEx", SetLastError = true)] private static extern int LoadLibraryEx(string lpFileName, IntPtr hReservedNull, LoadLibraryFlags dwFlags); /// <summary> /// API GetProcAddress /// </summary> /// <param name="handle"></param> /// <param name="funcname"></param> /// <returns></returns> [DllImport("Kernel32", EntryPoint = "GetProcAddress", SetLastError = true)] public static extern int GetProcAddress(int handle, string funcname); /// <summary> /// API FreeLibrary /// </summary> /// <param name="handle"></param> /// <returns></returns> [DllImport("Kernel32", EntryPoint = "FreeLibrary", SetLastError = true)] private static extern int FreeLibrary(int handle); ///<summary> /// 通過(guò)非托管函數(shù)名轉(zhuǎn)換為對(duì)應(yīng)的委托 , by jingzhongrong ///</summary> ///<param name="dllModule"> 通過(guò) LoadLibrary 獲得的 DLL 句柄 </param> ///<param name="functionName"> 非托管函數(shù)名 </param> ///<param name="t"> 對(duì)應(yīng)的委托類(lèi)型 </param> ///<returns> 委托實(shí)例，可強(qiáng)制轉(zhuǎn)換為適當(dāng)?shù)奈蓄?lèi)型 </returns> public static Delegate GetFunctionAddress(int dllModule, string functionName, Type t) { int address = GetProcAddress(dllModule, functionName); if (address == 0) return null; else return Marshal.GetDelegateForFunctionPointer(new IntPtr(address), t); } ///<summary> /// 將表示函數(shù)地址的 intPtr 實(shí)例轉(zhuǎn)換成對(duì)應(yīng)的委托 ///</summary> public static Delegate GetDelegateFromIntPtr(IntPtr address, Type t) { if (address == IntPtr.Zero) return null; else return Marshal.GetDelegateForFunctionPointer(address, t); } ///<summary> /// 將表示函數(shù)地址的 int 轉(zhuǎn)換成對(duì)應(yīng)的委托 ///</summary> public static Delegate GetDelegateFromIntPtr(int address, Type t) { if (address == 0) return null; else return Marshal.GetDelegateForFunctionPointer(new IntPtr(address), t); } /// <summary> /// 加載sdk /// </summary> /// <param name="lpFileName"></param> /// <returns></returns> public static int LoadSDK(string lpFileName) { if (File.Exists(lpFileName)) { var hReservedNull = IntPtr.Zero; var dwFlags = LoadLibraryFlags.LOAD_WITH_ALTERED_SEARCH_PATH; var result = LoadLibraryEx(lpFileName, hReservedNull, dwFlags); var errCode = GetLastError(); LogHelper.Info($"LoadSDK Result:{result}, ErrorCode: {errCode}"); return result; } return 0; } /// <summary> /// 釋放sdk /// </summary> /// <param name="handle"></param> /// <returns></returns> public static int ReleaseSDK(int handle) { try { if (handle > 0) { LogHelper.Info($"FreeLibrary handle：{handle}"); var result = FreeLibrary(handle); var errCode = GetLastError(); LogHelper.Info($"FreeLibrary Result:{result}, ErrorCode: {errCode}"); return 0; } return -1; } catch (Exception ex) { LogHelper.Error(ex); return -1; } } } /// <summary> /// LoadLibraryFlags /// </summary> public enum LoadLibraryFlags : uint { /// <summary> /// DONT_RESOLVE_DLL_REFERENCES /// </summary> DONT_RESOLVE_DLL_REFERENCES = 0x00000001, /// <summary> /// LOAD_IGNORE_CODE_AUTHZ_LEVEL /// </summary> LOAD_IGNORE_CODE_AUTHZ_LEVEL = 0x00000010, /// <summary> /// LOAD_LIBRARY_AS_DATAFILE /// </summary> LOAD_LIBRARY_AS_DATAFILE = 0x00000002, /// <summary> /// LOAD_LIBRARY_AS_DATAFILE_EXCLUSIVE /// </summary> LOAD_LIBRARY_AS_DATAFILE_EXCLUSIVE = 0x00000040, /// <summary> /// LOAD_LIBRARY_AS_IMAGE_RESOURCE /// </summary> LOAD_LIBRARY_AS_IMAGE_RESOURCE = 0x00000020, /// <summary> /// LOAD_LIBRARY_SEARCH_APPLICATION_DIR /// </summary> LOAD_LIBRARY_SEARCH_APPLICATION_DIR = 0x00000200, /// <summary> /// LOAD_LIBRARY_SEARCH_DEFAULT_DIRS /// </summary> LOAD_LIBRARY_SEARCH_DEFAULT_DIRS = 0x00001000, /// <summary> /// LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR /// </summary> LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR = 0x00000100, /// <summary> /// LOAD_LIBRARY_SEARCH_SYSTEM32 /// </summary> LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800, /// <summary> /// LOAD_LIBRARY_SEARCH_USER_DIRS /// </summary> LOAD_LIBRARY_SEARCH_USER_DIRS = 0x00000400, /// <summary> /// LOAD_WITH_ALTERED_SEARCH_PATH /// </summary> LOAD_WITH_ALTERED_SEARCH_PATH = 0x00000008 } }
2. 使用DLLWrapper類(lèi)動(dòng)態(tài)讀取C++Dll，獲得函數(shù)指針，并且將指針?lè)庋b成C#中的委托。原因很簡(jiǎn)單，C#中已經(jīng)不能使用指針了，如下： 定義委托 UnmanagedFunctionPointer(CallingConvention.StdCall, CharSet = CharSet.Ansi)] public delegate int Delegate_IKUSBSDK_GetVersion([In] [Out] [MarshalAs(UnmanagedType.LPArray)] byte[] version);
3. 調(diào)用函數(shù) //1. 加載sdk var sdkModule = DLLWrapper.LoadSDK(_route.DeviceA_PATH); // 2. 通過(guò)handle 找到相關(guān)的函數(shù) Delegate_IKUSBSDK_GetVersion getVersion = (Delegate_IKUSBSDK_GetVersion)DLLWrapper.GetFunctionAddress(sdkModule, "IKUSBSDK_GetVersion", typeof(Delegate_IKUSBSDK_GetVersion)); var result = getVersion(version);
最后通過(guò)如上例子，我們可以在C#中動(dòng)態(tài)或者靜態(tài)的調(diào)用C++寫(xiě)的代碼了。
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