C#调用WIN32API系列二列举局网内共享打印机

你是第56位浏览该文章的人 romatic(收藏) csdn 2003-8-3

首先我们看看EnumPrinters函数的定义

BOOL EnumPrinters(
    DWORD Flags, // printer object types
    LPTSTR Name, // name of printer object
    DWORD Level, // information level
    LPBYTE pPrinterEnum, // printer information buffer
    DWORD cbBuf, // size of printer information buffer
    LPDWORD pcbNeeded, // bytes received or required
    LPDWORD pcReturned // number of printers enumerated
);

这个api有几个返回参数, 其中最重要的是pPrinterEnum所指的缓冲区中，是一个PRINTER_INFO_N的结构数组, 这里N根据Level参数而变化, 这里我们用的是1, 所以用到的结构是

typedef struct _PRINTER_INFO_1 {
    DWORD Flags;
    LPTSTR pDescription;
    LPTSTR pName;
    LPTSTR pComment;
} PRINTER_INFO_1

C#要调用API首先要引入动态库，EnumPrinters在winspool.drv这个动态库中。引入语句如下

[DllImport("winspool.drv", CharSet=CharSet.Auto)]

然后是定义PRINTER_INFO_1结构

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
struct PRINTER_INFO_1
{
    int flags;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string pDescription;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string pName;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string pComment;
}

好了，全部的源代码如下：

using System;
using System.Collections;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Drawing.Printing;
public class QuickTest
{
    [DllImport("winspool.drv", CharSet = CharSet.Auto)]
    static extern bool EnumPrinters(int flags, string name, int level, IntPtr pPrinterEnum,
            int cbBuf, out int pcbNeeded, out int pcReturned);

    private const int PRINTER_ENUM_NETWORK = 0x00000040;
    private const int PRINTER_ENUM_LOCAL = 0x00000002;
    private const int PRINTER_ENUM_REMOTE = 0x00000010;
    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    struct PRINTER_INFO_1
    {
        int flags;
        [MarshalAs(UnmanagedType.LPTStr)]
        public string pDescription;
        [MarshalAs(UnmanagedType.LPTStr)]
        public string pName;
        [MarshalAs(UnmanagedType.LPTStr)]
        public string pComment;
    }

    public void EnumeratePrintersWin()
    {
        bool Success;
        int cbRequired;
        int nEntries;

        IntPtr outb = IntPtr.Zero;

        Success = EnumPrinters(PRINTER_ENUM_NETWORK | PRINTER_ENUM_LOCAL | PRINTER_ENUM_REMOTE, null, 1, outb, 0, out cbRequired, out nEntries);
        outb = Marshal.AllocHGlobal(cbRequired);
        Success = EnumPrinters(PRINTER_ENUM_NETWORK | PRINTER_ENUM_LOCAL | PRINTER_ENUM_REMOTE, null, 1, outb, cbRequired, out cbRequired, out nEntries);

        PRINTER_INFO_1[] portsArray = new PRINTER_INFO_1[cbRequired];

        IntPtr current = outb;
        try
        {
            for (int i = 0; i < portsArray.Length; i++)
            {
                portsArray[i] = (PRINTER_INFO_1)Marshal.PtrToStructure(current, typeof(PRINTER_INFO_1));
                current = (IntPtr)((int)current + Marshal.SizeOf(typeof(PRINTER_INFO_1)));
                Console.WriteLine(i + ": \n" + portsArray[i].pName + "\n" + portsArray[i].pDescription + "\n" + portsArray[i].pComment + "\n");
            }
        }
        catch (Exception)
        {
            //Console.WriteLine(exp.StackTrace);
        }
        Marshal.FreeHGlobal(outb);
    }
    public QuickTest()
    {

    }
    public static void Main()
    {
        QuickTest qt = new QuickTest();
        qt.EnumeratePrintersWin();
    }
}