终于成功了。需要说明的是：
1.下面的例子只给出了basic_ifstream，还需要改写basic_ofstream和basic_fstream，不过是大同小异的工作。
2.当移植到UNIX平台时，需要改写例子中和操作系统中有关的部分。
3.算了算，我仅仅增加了11行代码就完成了对std::basic_ifstream的改造，这种改造对标准库是完全透明的，即使加上另外两个类也不超过50行的代码量，却获得了操作系统底层的文件句柄，使得移花接木成为可能。
#include <fstream>
namespace ashura {
// TEMPLATE CLASS basic_ifstream
template<class _E, class _Tr = char_traits<_E> >
class basic_ifstream : public std::basic_istream<_E, _Tr> {
public:
typedef basic_ifstream<_E, _Tr> _Myt;
typedef std::basic_filebuf<_E, _Tr> _Myfb;
basic_ifstream()
: std::basic_istream<_E, _Tr>(&_Fb) {}
//explicit basic_ifstream(const char *_S,
// std::ios_base::openmode _M = in)
// : std::basic_istream<_E, _Tr>(&_Fb)
// {if (_Fb.open(_S, _M | in) == 0)
// setstate(failbit); }
///////// my code begin /////////
explicit basic_ifstream(const char *_S,
std::ios_base::openmode _M = in)
: std::basic_istream<_E, _Tr>(&_Fb), _file(_S, _M | in), _Fb(_file.f)
{if (!_file.isopen())
setstate(failbit); }
FILE* get_handle() { return _file.f; }
///////// my code end /////////
virtual ~basic_ifstream()
{}
_Myfb *rdbuf() const
{return ((_Myfb *)&_Fb); }
bool is_open() const
{return (_Fb.is_open()); }
void open(const char *_S, std::ios_base::openmode _M = in)
{if (_Fb.open(_S, _M | in) == 0)
setstate(failbit); }
void open(const char *_S, std::ios_base::open_mode _M)
{open(_S, (openmode)_M); }
void close()
{if (_Fb.close() == 0)
setstate(failbit); }
private:
///////// my code begin /////////
struct osfile{
osfile(const char *_S, std::ios_base::openmode _M) : f(std::__Fiopen(_S, _M)) { };
bool isopen() { return f!=0; }
FILE* f;
} _file;
///////// my code end /////////
_Myfb _Fb;
};
typedef basic_ifstream<char, std::char_traits<char> > ifstream;
}
#include <string>
#include <iostream>
#include <windows.h>
#include <io.h>
int main()
{
ashura::ifstream f("c:\\test.txt");
HANDLE hFile = reinterpret_cast<HANDLE>(_get_osfhandle(f.get_handle()->_file));
BY_HANDLE_FILE_INFORMATION file_info;
BOOL bSuccess = GetFileInformationByHandle(hFile,&file_info);
using namespace std;
string str;
f >> str;
cout << bSuccess << " " << str << endl;
}
//output:
//1 hello
