我们有一些用 C# 编写的打印服务器软件(其中 P/Invokes 函数来自 winspool.drv)。一些“打印机”实际上是打印到目录的虚拟打印机。安装这种打印机的代码是:
public override void AddLocalDirectoryPrinter(string printerName, string directory)
{
IntPtr hPrinter = IntPtr.Zero;
try
{
PRINTER_DEFAULTS pd;
PRINTER_INFO_2 pi2;
pd.datatype = null;
pd.pDevMode = IntPtr.Zero;
// Access = PRINTER_ALL_ACCESS
// http://msdn.microsoft.com/en-us/library/cc244650%28v=prot.10%29.aspx
pd.desiredAccess = PRINTER_ALL_ACCESS;
// Attributes = PUBLISHED | DO_COMPLETE_FIRST | SHARED
// http://msdn.microsoft.com/en-us/library/aa394363%28v=vs.85%29.aspx
pi2.attributes = 0x2208;
pi2.averagePpm = 0;
pi2.jobs = 0;
pi2.defaultPriority = 0;
pi2.comment = "Auto-Generated by [name of program]";
pi2.datatype = "RAW";
pi2.pDevMode = IntPtr.Zero;
pi2.driverName = "Generic / Text Only";
pi2.location = string.Empty;
pi2.parameters = string.Empty;
pi2.portName = directory;
pi2.printerName = printerName.ToUpperInvariant();
pi2.printProcessor = "WinPrint";
pi2.priority = 0;
pi2.pSecurityDescriptor = IntPtr.Zero;
pi2.sepFile = string.Empty;
pi2.serverName = string.Empty;
pi2.shareName = printerName.ToUpperInvariant();
pi2.startTime = 0;
pi2.status = 0;
pi2.untilTime = 0;
hPrinter = AddPrinter(null, 2, ref pi2);
if (hPrinter == IntPtr.Zero)
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
catch (Exception ex)
{
throw new PrintingException("Failed to add printer", ex);
}
finally
{
if (hPrinter != IntPtr.Zero)
{
ClosePrinter(hPrinter);
}
}
}
在 32 位 Windows XP 上,上述代码可以正常运行。但在 64 位 Windows 7 上,对AddPrinter的调用失败并出现 Windows 错误 1796(“指定的端口未知”)。
为什么它可以在一个版本的 Windows 上运行,而不能在另一个版本上运行?