C#获得打印句柄
PrintDocument pdc = new PrintDocument();
string printerName = pdc.PrinterSettings.PrinterName;
IntPtr pPrinter = IntPtr.Zero;
IntPtr nullPointer = IntPtr.Zero;
if (printerName != null && printerName.Length > 0)
{
OpenPrinter(printerName, ref pPrinter, ref nullPointer);
}