解决智能卡 读卡时出现 SCARD_E_SERVICE_STOPPED问题

调用SCardListReaders（）函数返回SCARD_E_SERVICE_STOPPED；

先执行
SCardReleaseContext（）；
再执行
SCardEstablishContext（）；

LPTSTR          pmszReaders = NULL;
LPTSTR          pReader;
LONG            lReturn, lReturn2;
DWORD           cch = SCARD_AUTOALLOCATE;

// Retrieve the list the readers.
// hSC was set by a previous call to SCardEstablishContext.
lReturn = SCardListReaders(hSC,
                           NULL,
                           (LPTSTR)&pmszReaders,
                           &cch );
switch( lReturn )
{
    case SCARD_E_NO_READERS_AVAILABLE:
        printf("Reader is not in groups./n");
        // Take appropriate action.
        // ...
        break;
    case SCARD_S_SUCCESS:
        // Do something with the multi string of readers.
        // Output the values.
        // A double-null terminates the list of values.
        pReader = pmszReaders;
        while ( '/0' != *pReader )
        {
            // Display the value.
            printf("Reader: %S/n", pReader );
            // Advance to the next value.
            pReader = pReader + wcslen((wchar_t *)pReader) + 1;
        }
        // Free the memory.
        lReturn2 = SCardFreeMemory( hSC,
                                   pmszReaders );
        if ( SCARD_S_SUCCESS != lReturn2 )
            printf("Failed SCardFreeMemory/n");
        break;
default:
        printf("Failed SCardListReaders/n");
		SCardReleaseContext();
		SCardEstablishContext();

        break;
}