.NET – 深入系统编程 - Part 1
介绍
在我以前的文章里面，我举了很多系统编程的例子。很多年前，我特别喜欢琢磨系统表格以及系统工具。当然，那时我还没有一个真正PC，只是类似于IBM360、PDP11或者microVAX，但是那种感觉不错。这些年我依然喜欢在COM接口、DLL库和硬盘配置上作些研究。啊哈，我一直喜欢系统编程！
目的
很多人认为C#只是一个 "child language" 。在我看来，这绝对是错误的！为了证明我的观点，我准备编写三个关于硬件设备配置的例子，展现如何使用C#和Win32 API（甚至DDK）一起工作。主要是使用P/Invoke来实现。同时C#非常完美的解决了不同平台数据交流的问题，以及通过Windows Forms ，使我们更容易使用应用程序。
设备类
All devices in the system join in the device classes. As you can see in the below picture, the class has name and Guid (so it can be found in Registry). The class can also have a description. For example, for class "Ports" the description is "Ports (COM & LPT)". Class also has devices that are present in the configuration.
所有的设备信息都存在于设备类中。这个类拥有名字和Guid（因此它可以在注册表中被找到）。这个类还有一些描述，比如类"Ports"的描述是"Ports (COM & LPT)"。
系统设备管理器给出了所有在PC上存在的设备类的信息：
下面，你将看到使用C#遍历所有设备的例子，它使用了P/Invoke、DDK和SDK DLLs。
using System;
using System.Runtime.InteropServices;// P/Invoke 必需
using System.Text;
namespace DevClasses
{
/// <summary>
/// Summary description for Class.
/// </summary>
class DeviceClasses
{
/// <summary>
/// The main entry point for the application.
/// </summary>
public const int MAX_NAME_PORTS=7;
public const int RegDisposition_OpenExisting=(0x00000001);
// open key only if exists
public const int CM_REGISTRY_HARDWARE=(0x00000000);
public const int CR_SUCCESS = (0x00000000);
public const int CR_NO_SUCH_VALUE = (0x00000025);
public const int CR_INVALID_DATA = (0x0000001F);
public const int DIGCF_PRESENT = (0x00000002);
public const int DIOCR_INSTALLER = (0x00000001);
// MaximumAllowed access type to Reg.
public const int MAXIMUM_ALLOWED = (0x02000000);
[StructLayout(LayoutKind.Sequential)] //为了保证数据交流顺利
public class SP_DEVINFO_DATA //struct 也可以
{
public int cbSize;
public Guid ClassGuid;
public int DevInst; // DEVINST handle
public ulong Reserved;
};
//声明函数原型
[DllImport("cfgmgr32.dll")]
public static extern UInt32
CM_Open_DevNode_Key(IntPtr dnDevNode, UInt32 samDesired,
UInt32 ulHardwareProfile,
UInt32 Disposition,IntPtr phkDevice, UInt32 ulFlags);
[DllImport("cfgmgr32.dll")]
public static extern UInt32
CM_Enumerate_Classes(UInt32 ClassIndex,ref Guid ClassGuid, UInt32 Params);
[DllImport("setupapi.dll")]//
public static extern Boolean
SetupDiClassNameFromGuidA(ref Guid ClassGuid,
StringBuilder ClassName, //char * ?
UInt32 ClassNameSize, ref UInt32 RequiredSize);
[DllImport("setupapi.dll")]
public static extern IntPtr
SetupDiGetClassDevsA(ref Guid ClassGuid, UInt32 Enumerator,
IntPtr hwndParent, UInt32 Flags);
[DllImport("setupapi.dll")]
public static extern Boolean
SetupDiEnumDeviceInfo(IntPtr DeviceInfoSet, UInt32 MemberIndex,
ref SP_DEVINFO_DATA DeviceInfoData);
[DllImport("setupapi.dll")]
public static extern Boolean
SetupDiDestroyDeviceInfoList(IntPtr DeviceInfoSet);
[DllImport("setupapi.dll")]
public static extern IntPtr
SetupDiGetClassDevsA(ref Guid ClassGuid, UInt32 samDesired,
UInt32 Flags, ref string hwndParent, IntPtr Reserved);
[DllImport("setupapi.dll")]
public static extern IntPtr
SetupDiOpenClassRegKeyExA(
ref Guid ClassGuid, UInt32 samDesired, int Flags, IntPtr MachineName,
UInt32 Reserved);
[DllImport("advapi32.dll")]
public static extern UInt32
RegQueryValueA(IntPtr KeyClass,UInt32 SubKey,
StringBuilder ClassDescription,ref UInt32 sizeB);
[DllImport("user32.dll")]
public static extern Boolean
CharToOem(String lpszSrc, StringBuilder lpszDst);
//遍历
public static int EnumerateClasses(UInt32 ClassIndex,
ref StringBuilder ClassName, StringBuilder ClassDescription,
ref bool DevicePresent)
{
Guid ClassGuid=Guid.Empty;
IntPtr NewDeviceInfoSet;
SP_DEVINFO_DATA DeviceInfoData;
UInt32 result;
StringBuilder name=new StringBuilder("");
bool resNam=false;
UInt32 RequiredSize=0;
IntPtr ptr;
result = CM_Enumerate_Classes(ClassIndex, ref ClassGuid,0);
ClassName=new StringBuilder("");
DevicePresent=false;
//incorrect device class:
if(result == CR_INVALID_DATA)
{
return -2;
}
//device class is absent
if(result == CR_NO_SUCH_VALUE)
{
return -1;
}
//bad param. - fatal error
if(result != CR_SUCCESS)
{
return -3;
}
name.Capacity=0;
resNam=SetupDiClassNameFromGuidA(ref ClassGuid,name,RequiredSize,
ref RequiredSize);
if(RequiredSize > 0)
{
name.Capacity=(int)RequiredSize;
resNam=SetupDiClassNameFromGuidA(ref ClassGuid,name,
RequiredSize,ref RequiredSize);
}
NewDeviceInfoSet=SetupDiGetClassDevsA(
ref ClassGuid,
0,
IntPtr.Zero,
DIGCF_PRESENT);
if(NewDeviceInfoSet.ToInt32() == -1)
{ DevicePresent=false;
ClassName=name;
return 0;}
IntPtr KeyClass=SetupDiOpenClassRegKeyExA(
ref ClassGuid, MAXIMUM_ALLOWED, DIOCR_INSTALLER,IntPtr.Zero,0);
if(KeyClass.ToInt32() == -1)
{ DevicePresent=false;
ClassName=name;
return 0;}
UInt32 sizeB=1000;
String abcd="";
StringBuilder CD=new StringBuilder("");
ClassDescription.Capacity=1000;
UInt32 res=RegQueryValueA(KeyClass,0,ClassDescription,ref sizeB);
if(res != 0)ClassDescription=new StringBuilder("");
SetupDiDestroyDeviceInfoList(NewDeviceInfoSet);
ClassName=name;
DevicePresent=true;
return 0;
}
[STAThread]
static void Main(string[] args)
{
StringBuilder classes=new StringBuilder("");
StringBuilder classesDescr=new StringBuilder("");
StringBuilder classesDescrOEM=new StringBuilder("");
classesDescrOEM.Capacity=1000;
Boolean DevExist=false;
UInt32 i=0;
while(true)
{
int res=EnumerateClasses(i,ref classes,classesDescr,ref DevExist);
if(res == -1)
break;
++i;
if(res < -1 || !DevExist)continue;
Console.WriteLine("ClassName={0}, Description={1}",classes,classesDescr);
}
return;
}
}
}
运行这个应用程序之后，你将看到你机器上的所有设备类。
出自:
http://www.codeproject.com/csharp/DivingSysProg1.asp
译者的话：
这只是作者一系列文章中的第一章。没有太多的深入讲解知识，只是举了一个例子而已。
PS:
原文有图片，这里可能看不到，可以到我的主页上看这篇文章。
