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(,',','); } }
