我要问并回答我自己的问题。我原本以为需要创建一个空打印机并不是一件罕见的事情，但是在我有一个可行的解决方案之前，我花了很长时间用谷歌搜索和组装碎片。我发现很多关于通过Windows GUI创建一个空打印机的答案，但是以编程方式执行它的信息相对稀少和分散。希望我的答案或它引出的更好的建议将为其他一些糟糕的shmo节省一些时间。
答案 0 :(得分：2)
这＆＃34;为我工作＆＃34;。我想有一个更优雅的方法来实现这一点，我期待任何改进/纠正代码的建议，但我无法找到一个简洁的完整答案，我认为这是一个相对常见的需求。我有一个相当具体的要求，显然这个代码可以推广，可以添加适当的错误处理等。
//pd is a PrintDocument. used like:
PrintController printController = new StandardPrintController();
pd.PrintController = printController;
NullPrinter np = new NullPrinter();
if (!np.NullPortExists())
{
np.CreateNullPort();
}
if (!np.NullPrinterExists())
{
np.CreateNullPrinter();
}
pd.PrinterSettings.PrinterName = "NUL_PRINTER";
/*********************************************/
using System;
using System.Management; // This must also be added as a reference
using System.Drawing.Printing;
using System.Runtime.InteropServices;
namespace YourFavoriteNamespace
{
//
// This helper class has methods to determine whether a 'Nul Printer' exists,
// and to create a null port and null printer if it does not.
//
public class NullPrinter
{
// Printer port management via Windows GUI (Windows 7, probably same in other versions):
//
// Go to printers & devices
// Select any printer
// Click on Print server properties
// Select Ports tab
// Add or remove (local) port
// To remove a local port, if "in use", stop and restart the print spooler service.
// It seems that the most recently used port will be "in use" until the system restarts,
// or until another port is used.
// A port may also be added when adding a printer.
// Valid names for a Null port appear to be NUL, NULL, NUL: - all case insensitive.
public bool NullPortExists()
{
for (int i = 0; i < PrinterSettings.InstalledPrinters.Count; i++)
{
string printerName = PrinterSettings.InstalledPrinters[i];
string query = string.Format("SELECT * from Win32_Printer WHERE Name LIKE '%{0}'", printerName);
ManagementObjectSearcher searcher = new ManagementObjectSearcher(query);
ManagementObjectCollection coll = searcher.Get();
foreach (ManagementObject printer in coll)
{
string pName = printer["PortName"].ToString();
if (pName.Equals("NULL", StringComparison.InvariantCultureIgnoreCase) ||
pName.Equals("NUL", StringComparison.InvariantCultureIgnoreCase) ||
pName.Equals("NUL:", StringComparison.InvariantCultureIgnoreCase))
{
return true;
}
}
}
return false;
}
// The application that uses this requires a printer specifically named "NUL_PRINTER"
public bool NullPrinterExists()
{
for (int i = 0; i < PrinterSettings.InstalledPrinters.Count; i++)
{
if (PrinterSettings.InstalledPrinters[i] == "NUL_PRINTER")
{
return true;
}
}
return false;
}
public bool CreateNullPort()
{
return Winspool.AddLocalPort("NUL") == 0 ? true : false;
}
public void CreateNullPrinter()
{
Winspool.AddPrinter("NUL_PRINTER");
}
}
/*********************************************************/
//
// This Winspool class was mostly borrowed and adapted
// from several different people's blog posts,
// the links to which I have lost.
// Thank you, whoever you are.
//
public static class Winspool
{
[StructLayout(LayoutKind.Sequential)]
private class PRINTER_DEFAULTS
{
public string pDatatype;
public IntPtr pDevMode;
public int DesiredAccess;
}
[DllImport("winspool.drv", CharSet = CharSet.Auto)]
static extern IntPtr AddPrinter(string pName, uint Level, [In] ref PRINTER_INFO_2 pPrinter);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
struct PRINTER_INFO_2
{
public string pServerName,
pPrinterName,
pShareName,
pPortName,
pDriverName,
pComment,
pLocation;
public IntPtr pDevMode;
public string pSepFile,
pPrintProcessor,
pDatatype,
pParameters;
public IntPtr pSecurityDescriptor;
public uint Attributes,
Priority,
DefaultPriority,
StartTime,
UntilTime,
Status,
cJobs,
AveragePPM;
}
[DllImport("winspool.drv", EntryPoint = "XcvDataW", SetLastError = true)]
private static extern bool XcvData(
IntPtr hXcv,
[MarshalAs(UnmanagedType.LPWStr)] string pszDataName,
IntPtr pInputData,
uint cbInputData,
IntPtr pOutputData,
uint cbOutputData,
out uint pcbOutputNeeded,
out uint pwdStatus);
[DllImport("winspool.drv", EntryPoint = "OpenPrinterA", SetLastError = true)]
private static extern int OpenPrinter(
string pPrinterName,
ref IntPtr phPrinter,
PRINTER_DEFAULTS pDefault);
[DllImport("winspool.drv", EntryPoint = "ClosePrinter")]
private static extern int ClosePrinter(IntPtr hPrinter);
public static int AddLocalPort(string portName)
{
PRINTER_DEFAULTS def = new PRINTER_DEFAULTS();
def.pDatatype = null;
def.pDevMode = IntPtr.Zero;
def.DesiredAccess = 1; //Server Access Administer
IntPtr hPrinter = IntPtr.Zero;
int n = OpenPrinter(",XcvMonitor Local Port", ref hPrinter, def);
if (n == 0)
return Marshal.GetLastWin32Error();
if (!portName.EndsWith("\0"))
portName += "\0"; // Must be a null terminated string
// Must get the size in bytes. .NET strings are formed by 2-byte characters
uint size = (uint)(portName.Length * 2);
// Alloc memory in HGlobal to set the portName
IntPtr portPtr = Marshal.AllocHGlobal((int)size);
Marshal.Copy(portName.ToCharArray(), 0, portPtr, portName.Length);
uint NotUsedByUs;
uint xcvResult;
XcvData(hPrinter, "AddPort", portPtr, size, IntPtr.Zero, 0, out NotUsedByUs, out xcvResult);
ClosePrinter(hPrinter);
Marshal.FreeHGlobal(portPtr);
return (int)xcvResult;
}
public static void AddPrinter(string PrinterName)
{
IntPtr mystrptr = new IntPtr(0);
IntPtr mysend2;
PRINTER_INFO_2 pi = new PRINTER_INFO_2();
pi.pServerName = "";
pi.pPrinterName = PrinterName;
pi.pShareName = "NUL";
pi.pPortName = "NUL";
pi.pDriverName = "Generic / Text Only";
pi.pComment = "No Comment";
pi.pLocation = "Local";
pi.pDevMode = mystrptr;
pi.pSepFile = "";
pi.pPrintProcessor = "WinPrint";
pi.pDatatype = "RAW";
pi.pParameters = "";
pi.pSecurityDescriptor = mystrptr;
mysend2 = AddPrinter(null,2, ref pi);
}
}
}