字符集WideCharToMultiByte

GDAL C#封装对中文字符转换过程中存在问题。

C++封装一个Win32 DLL，采用Unicode字符集。使用标准头文件。

https://msdn.microsoft.com/en-us/library/dd319072(VS.85).aspx

 class CodePageHelper
 {
 public:
     CodePageHelper(void);
     ~CodePageHelper(void);
     static wchar_t*  ANSIToUnicode( const char* str );
     static char* UnicodeToANSI( const wchar_t* str );
     static wchar_t* UTF8ToUnicode( const char* str );
     static char* UnicodeToUTF8( const wchar_t* str );
 };

CodePageHelper.h

 #include "StdAfx.h"
 #include "CodePageHelper.h"

 CodePageHelper::CodePageHelper(void)
 {
 }

 CodePageHelper::~CodePageHelper(void)
 {
 }

 // ANSI to Unicode
  wchar_t* CodePageHelper:: ANSIToUnicode( const char* str )
 {
  int  unicodeLen = ::MultiByteToWideChar( CP_ACP,
             ,
             str,
             -,
             NULL,
              );
  wchar_t *  pUnicode;
  pUnicode = new  wchar_t[unicodeLen+];
  memset(pUnicode,,(unicodeLen+)*sizeof(wchar_t));
  ::MultiByteToWideChar( CP_ACP,
          ,
          str,
          -,
          (LPWSTR)pUnicode,
          unicodeLen );
  wchar_t*  rt;
  rt = ( wchar_t* )pUnicode;
  //delete  pUnicode; 

  return  rt;
 }
 //  Unicode to ANSI
  char* CodePageHelper:: UnicodeToANSI( const wchar_t* str )
 {
  char*     pElementText;
  int    iTextLen;
  // wide char to multi char
  iTextLen = WideCharToMultiByte( CP_ACP,
          ,
          str,
          -,
          NULL,
          ,
 NULL,
          NULL );
  pElementText = new char[iTextLen + ];
  memset( ( void* )pElementText, , sizeof( char ) * ( iTextLen +  ) );
  ::WideCharToMultiByte( CP_ACP,
          ,
          str,
          -,
          pElementText,
          iTextLen,
          NULL,
          NULL );
  char* strText;
  strText = pElementText;
  //delete[] pElementText;
  return strText;
 }
 //  UTF-8 to Unicode
  wchar_t* CodePageHelper::UTF8ToUnicode( const char* str )
 {
  int  unicodeLen = ::MultiByteToWideChar( CP_UTF8,
             ,
             str,
             -,
             NULL,
              );
  wchar_t *  pUnicode;
  pUnicode = new  wchar_t[unicodeLen+];
  memset(pUnicode,,(unicodeLen+)*sizeof(wchar_t));
  ::MultiByteToWideChar( CP_UTF8,
          ,
          str,
          -,
          (LPWSTR)pUnicode,
          unicodeLen );
  wchar_t*  rt;
  rt = ( wchar_t* )pUnicode;
  //delete  pUnicode; 

  return  rt;
 }
 //  Unicode to UTF-8    

  char* CodePageHelper::UnicodeToUTF8( const wchar_t* str )
 {
  char*     pElementText;
  int    iTextLen;
  // wide char to multi char
  iTextLen = WideCharToMultiByte( CP_UTF8,
          ,
          str,
          -,
          NULL,
          ,
          NULL,
          NULL );
  pElementText = new char[iTextLen + ];
  memset( ( void* )pElementText, , sizeof( char ) * ( iTextLen +  ) );
  ::WideCharToMultiByte( CP_UTF8,
          ,
          str,
          -,
          pElementText,
          iTextLen,
          NULL,
          NULL );
  char* strText;
  strText = pElementText;
  //delete[] pElementText;
  return strText;
 }

CodePageHelper

 #ifdef DEMIMP_EXPORTS
 #define CPL_DLL __declspec(dllexport)
 #else
 #define CPL_DLL __declspec(dllimport)
 #endif

 #ifndef CPL_DISABLE_STDCALL
 #  define CPL_STDCALL __stdcall
 #endif

 extern "C"
 {
     HANDLE CPL_DLL WINAPI GetMetaData(LPWSTR filepath);
 };

GDALRaster.h

 HANDLE CPL_DLL WINAPI GetMetaData(LPWSTR filepath)
 {
     //char*  file=CodePageHelper::UnicodeToUTF8((const wchar_t*)filepath);

     char*  file1=CodePageHelper::UnicodeToANSI((const wchar_t*)filepath);
     //const wchar_t* file2=filepath;
     GDALAllRegister();
     CPLSetConfigOption("GDAL_FILENAME_IS_UTF8","NO");
     GDALDataset *pDSrc = (GDALDataset *)GDALOpen(file1, GA_ReadOnly);
     if (pDSrc == NULL)
     {
         return ;
     }
     char** metadata=pDSrc->GetMetadata("");
     return metadata;
 }

C# P/Invoke调用：

  [DllImport("GDALRaster.dll", EntryPoint = "GetMetaData", CharSet = CharSet.Unicode)]
         private static extern IntPtr CSharp_GetMetadata([In, MarshalAs(UnmanagedType.LPWStr)]string filepath);

解析字符串：

 public static string[] GetMetaData(string filePath)
         {
             IntPtr cPtr = CSharp_GetMetadata(filePath);
             if (cPtr == IntPtr.Zero) throw new Exception("打开失败");

             IntPtr objPtr;
             int count = ;
             if (cPtr != IntPtr.Zero)
             {
                 while (Marshal.ReadIntPtr(cPtr, count * IntPtr.Size) != IntPtr.Zero)
                     ++count;
             }
             string[] ret = new string[count];
             if (count > )
             {
                 for (int cx = ; cx < count; cx++)
                 {
                     objPtr = System.Runtime.InteropServices.Marshal.ReadIntPtr(cPtr, cx * System.Runtime.InteropServices.Marshal.SizeOf(typeof(IntPtr)));
                     ret[cx] = (objPtr == IntPtr.Zero) ? null : System.Runtime.InteropServices.Marshal.PtrToStringAnsi(objPtr);
                 }
             }
             return ret;
             //double[] temp = new double[xsize * ysize];
             //Marshal.Copy(pData, temp, 0, xsize * ysize);
             //FreeData(pData);
             //return temp;

         }