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C#调用WIN32API系列二列举局网内共享打印机

C#通过调用WIN32API可以实现非常强大的功能，本文将着重讲述如何通过调用WIN32API实现列举局域网络内所有共享的打印机。

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[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();

}

}

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