如何检查是否有默认打印机 (Windows)？

Question

我是否可以从应用程序（本机、Java 或 .Net）中使用 API 或注册表项来检查当前登录的用户是否配置了默认打印机？

更新：非常感谢到目前为止的答案！根据知识库文章http://support.microsoft.com/kb/156212，注册表项（读/写）仅记录到 Windows 2000。在较新版本中是否有用于本机访问的 Win API 方法？

Answer 1

在 .NET 中，此代码适用于我：

public static string DefaultPrinterName()
{
  string functionReturnValue = null;
  System.Drawing.Printing.PrinterSettings oPS 
    = new System.Drawing.Printing.PrinterSettings();

  try
  {
    functionReturnValue = oPS.PrinterName;
  }
  catch (System.Exception ex)
  {
    functionReturnValue = "";
  }
  finally
  {
    oPS = null;
  }
  return functionReturnValue;
}

来自： http://in.answers.yahoo.com/question/index?qid=20070920032312AAsSaPx

Answer 2

有一个 Java API 可以获取默认打印机：

PrintService defaultPrinter = PrintServiceLookup.lookupDefaultPrintService();

如果没有默认打印机或服务，则返回 null。这可以作为一个测试。

---

旧答案

这些信息可以在注册表中找到。您无法使用纯 Java 访问注册表，但有针对此问题的 JNDI 解决方案。所以基本上你必须测试注册表中是否存在某个键。而且，作为奖励，如果您到目前为止，您甚至应该能够获得默认打印机的名称:)

进一步阅读：

• Changing a User's Default Printer in the Registry
• jRegistryKey（例如，周围有更多的解决方案）

Answer 3

非托管Print Spooler API winspool.drv 中有一个函数。您可以调用GetDefaultPrinter函数返回默认打印机的名称。

这是非托管函数的 P/Invoke 签名：

[DllImport("winspool.drv", CharSet=CharSet.Auto, SetLastError=true)]
private static extern bool GetDefaultPrinter(
    StringBuilder buffer,
    ref int bufferSize);

使用该函数判断是否设置了默认打印机：

    public static bool IsDefaultPrinterAssigned()
    {
        //initialise size at 0, used to determine size of the buffer
        int size = 0;

        //for first call provide a null StringBuilder and 0 size to determine buffer size
        //return value will be false, as the call actually fails internally setting the size to the size of the buffer
        GetDefaultPrinter(null, ref size);

        if (size != 0)
        {
            //default printer set
            return true;
        }

        return false;
    }

使用该函数返回默认的打印机名称，如果没有设置默认则返回空字符串：

    public static string GetDefaultPrinterName()
    {
        //initialise size at 0, used to determine size of the buffer
        int size = 0;

        //for first call provide a null StringBuilder and 0 size to determine buffer size
        //return value will be false, as the call actually fails internally setting the size to the size of the buffer
        GetDefaultPrinter(null, ref size);

        if (size == 0)
        {
            //no default printer set
            return "";
        }

        StringBuilder printerNameStringBuilder = new StringBuilder(size);

        bool success = GetDefaultPrinter(printerNameStringBuilder, ref size);

        if (!success)
        {
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }

        return printerNameStringBuilder.ToString();
    }

在控制台应用程序中测试的完整代码：

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Text;

namespace DefaultPrinter
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(IsDefaultPrinterAssigned());
            Console.WriteLine(GetDefaultPrinterName());
            Console.ReadLine();
        }

        [DllImport("winspool.drv", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern bool GetDefaultPrinter(
            StringBuilder buffer,
            ref int bufferSize);

        public static bool IsDefaultPrinterAssigned()
        {
            //initialise size at 0, used to determine size of the buffer
            int size = 0;

            //for first call provide a null StringBuilder to and 0 size to determine buffer size
            //return value will be false, as the call actually fails internally setting the size to the size of the buffer
            GetDefaultPrinter(null, ref size);

            if (size != 0)
            {
                //default printer set
                return true;
            }

            return false;
        }

        public static string GetDefaultPrinterName()
        {
            //initialise size at 0, used to determine size of the buffer
            int size = 0;

            //for first call provide a null StringBuilder to and 0 size to determine buffer size
            //return value will be false, as the call actually fails internally setting the size to the size of the buffer
            GetDefaultPrinter(null, ref size);

            if (size == 0)
            {
                //no default printer set
                return "";
            }

            StringBuilder printerNameStringBuilder = new StringBuilder(size);

            bool success = GetDefaultPrinter(printerNameStringBuilder, ref size);

            if (!success)
            {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }

            return printerNameStringBuilder.ToString();
        }
    }
}