.Net中虽然类库很强的，但还是有些时候功能有限，掌握常用的api函数，会给我们解决问题提供另一种思路，下面给出自己常用到的Api函数，以备查询。

知道api函数，但却不知道c#或VB.net该如何声明，可以查询这个网站：http://pinvoke.net/

1，SetForegroundWindow

将窗口显示到最前面，前提是窗口没有最小化。

[DllImport("User32.dll")]

public static extern bool SetForegroundWindow(IntPtr hWnd);

2，ShowWindowAsync

显示窗口，如最小化后显示正常，这是异步的。

[DllImport("User32.dll")]

public static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);

public enum ShowState : int

{

SW_HIDE = 0,

SW_SHOWNORMAL = 1,

SW_NORMAL = 1,

SW_SHOWMINIMIZED = 2,

SW_SHOWMAXIMIZED = 3,

SW_MAXIMIZE = 3,

SW_SHOWNOACTIVATE = 4,

SW_SHOW = 5,

SW_MINIMIZE = 6,

SW_SHOWMINNOACTIVE = 7,

SW_SHOWNA = 8,

SW_RESTORE = 9,

SW_SHOWDEFAULT = 10,

SW_FORCEMINIMIZE = 11,

SW_MAX = 11

}

3，SendMessage

进程间通信，接受窗口要有消息循环才行。WM_COPYDATA

public const int WM_COPYDATA = 0x004A;

public struct COPYDATASTRUCT

{

public IntPtr dwData;

public int cbData;

[MarshalAs(UnmanagedType.LPStr)]

public string lpData;

}

[DllImport("User32.dll", EntryPoint = "SendMessage")]

public static extern int SendMessage(

IntPtr hWnd, // handle to destination window

int Msg, // message

int wParam, // first message parameter

ref COPYDATASTRUCT lParam // second message parameter

);

例子：

发送方：

byte[] sarr = System.Text.Encoding.Default.GetBytes(args[0]);

Winn32.COPYDATASTRUCT copyData = new Winn32.COPYDATASTRUCT();

copyData.cbData = sarr.Length + 1;

copyData.lpData = args[0];

copyData.dwData = (IntPtr)100; //这里随便写什么数字

Winn32.SendMessage(runningInstance.MainWindowHandle, Winn32.WM_COPYDATA, 0, ref copyData);

接收方

protected override void DefWndProc(ref Message m)

{

if (m.Msg == Winn32.WM_COPYDATA)

{

Winn32.COPYDATASTRUCT copyData = new Winn32.COPYDATASTRUCT();

Type type = copyData.GetType();

copyData = (Winn32.COPYDATASTRUCT)m.GetLParam(type);

this.textBox1.Text = copyData.lpData;

}

base.DefWndProc(ref m);

}

4，FindWindow

找到窗口句柄

[DllImport("User32.dll", EntryPoint = "FindWindow")]

private static extern int FindWindow(string lpClassName, string lpWindowName);

5，SetLocalTime

设定系统时间

[StructLayout(LayoutKind.Sequential)]

public struct SYSTEMTIME

{

public ushort wYear;

public ushort wMonth;

public ushort wDayOfWeek;

public ushort wDay;

public ushort wHour;

public ushort wMinute;

public ushort wSecond;

public ushort wMilliseconds;

public void FromDateTime(DateTime dateTime)

{

wYear = (ushort)dateTime.Year;

wMonth = (ushort)dateTime.Month;

wDayOfWeek = (ushort)dateTime.DayOfWeek;

wDay = (ushort)dateTime.Day;

wHour = (ushort)dateTime.Hour;

wMinute = (ushort)dateTime.Minute;

wSecond = (ushort)dateTime.Second;

wMilliseconds = (ushort)dateTime.Millisecond;

}

public DateTime ToDateTime()

{

return new DateTime(wYear, wMonth, wDay, wHour, wMinute, wSecond);

}

}

[DllImport("kernel32.dll")]

public static extern bool SetLocalTime(ref SYSTEMTIME Time);

6，SHGetFileInfo

获取执行文件的图标icon

[Flags]

enum SHGFI : int

{

/// <summary>get icon</summary>

Icon = 0x000000100,

/// <summary>get display name</summary>

DisplayName = 0x000000200,

/// <summary>get type name</summary>

TypeName = 0x000000400,

/// <summary>get attributes</summary>

Attributes = 0x000000800,

/// <summary>get icon location</summary>

IconLocation = 0x000001000,

/// <summary>return exe type</summary>

ExeType = 0x000002000,

/// <summary>get system icon index</summary>

SysIconIndex = 0x000004000,

/// <summary>put a link overlay on icon</summary>

LinkOverlay = 0x000008000,

/// <summary>show icon in selected state</summary>

Selected = 0x000010000,

/// <summary>get only specified attributes</summary>

Attr_Specified = 0x000020000,

/// <summary>get large icon</summary>

LargeIcon = 0x000000000,

/// <summary>get small icon</summary>

SmallIcon = 0x000000001,

/// <summary>get open icon</summary>

OpenIcon = 0x000000002,

/// <summary>get shell size icon</summary>

ShellIconSize = 0x000000004,

/// <summary>pszPath is a pidl</summary>

PIDL = 0x000000008,

/// <summary>use passed dwFileAttribute</summary>

UseFileAttributes = 0x000000010,

/// <summary>apply the appropriate overlays</summary>

AddOverlays = 0x000000020,

/// <summary>Get the index of the overlay in the upper 8 bits of the iIcon</summary>

OverlayIndex = 0x000000040,

}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]

public struct SHFILEINFO

{

public SHFILEINFO(bool b)

{

hIcon = IntPtr.Zero;

iIcon = 0;

dwAttributes = 0;

szDisplayName = "";

szTypeName = "";

}

public IntPtr hIcon;

public int iIcon;

public uint dwAttributes;

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]

public string szDisplayName;

[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]

public string szTypeName;

};

[DllImport("shell32.dll", CharSet = CharSet.Unicode)]//路径有中文字符，要用unicode

public static extern int SHGetFileInfo(

string pszPath,

int dwFileAttributes,

out SHFILEINFO psfi,

uint cbfileInfo,

SHGFI uFlags);

例子：

private static Icon GetIcon(string strPath, bool bSmall)

{

SHFILEINFO info = new SHFILEINFO(true);

int cbFileInfo = Marshal.SizeOf(info);

SHGFI flags;

if (bSmall)

flags = SHGFI.Icon | SHGFI.SmallIcon | SHGFI.UseFileAttributes;

else

flags = SHGFI.Icon | SHGFI.LargeIcon;

Win32API.SHGetFileInfo(strPath, 256, out info, (uint)cbFileInfo, flags);

return Icon.FromHandle(info.hIcon);

}

7，GetWindowThreadProcessId

得到句柄的进程和线程ID，返回的是线程ID，ref返回的是进程ID

[System.Runtime.InteropServices.DllImport("User32.dll")]

private static extern int GetWindowThreadProcessId(int Hwnd, ref int OutPressId);

例子：杀死excel进程

int processID = 0;

int threadID;

threadID = GetWindowThreadProcessId(excelApp.Hwnd, ref processID);

if (processID > 0)

{

System.Diagnostics.Process process = System.Diagnostics.Process.GetProcessById(processID);

if (process != null)

{

process.Kill();

}

}