最近一个项目中用到的一些API，在解决一些实际的问题上（特别是和外部程序打交道）的时候还是蛮有用的。具体的参数什么的网上都有！
代码
public class API
{
#region 窗口函数
[DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
[DllImport("user32.dll", EntryPoint = "FindWindowEx", SetLastError = true)]
public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);
[DllImport("user32.dll", EntryPoint = "SetForegroundWindow", SetLastError = true)]
public static extern void SetForegroundWindow(IntPtr hwnd);
[DllImport("user32.dll", EntryPoint = "GetWindow", SetLastError = true)]
public static extern IntPtr GetWindow(IntPtr hWnd, uint wCmd);
[DllImport("user32.dll", EntryPoint = "GetClassName", CharSet = CharSet.Unicode, SetLastError = true)]
internal static extern int GetClassName(IntPtr hWnd, StringBuilder buf, int nMaxCount);
[DllImport("user32.dll", EntryPoint = "SetWindowPos", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern bool SetWindowPos(IntPtr hWnd, int hwndinsertAfter, int x, int y, int cx, int cy, int wFlags);
//显示窗体（包括使得窗体最小化，最大化等等操作）
[DllImport("user32.dll ")]
public static extern bool ShowWindow(IntPtr hwnd, int cmdshow);
/// <summary>
/// 设置窗体标题
/// </summary>
/// <param name="hwnd">窗体句柄</param>
/// <param name="lpStrjng">要设置的标题</param>
/// <returns></returns>
[DllImport("user32.dll ")]
public static extern bool SetWindowText(IntPtr hwnd, string lpStrjng);
/// <summary>
/// 获得窗体的位置（相对于整个屏幕)
/// </summary>
/// <param name="hwnd">窗体句柄</param>
/// <param name="rc">自定义的矩形结构，请调用该类中的RectangleEx</param>
/// <returns></returns>
[DllImport("user32.dll")]
public static extern int GetWindowRect(IntPtr hwnd, ref RectangleEx rc);
public struct RectangleEx
{
public int leftTopX;
public int leftTopY;
public int rightBottomX;
public int rightBottomY;
public int Width
{
get { return rightBottomX - leftTopX; }
}
public int Height
{
get { return rightBottomY - leftTopY; }
}
}
/// <summary>
/// 获得包含指定点的窗口的句柄
/// </summary>
/// <param name="p">一个被检测的点的POINT结构</param>
/// <returns></returns>
[DllImport("user32.dll ")]
public static extern IntPtr WindowFromPoint(Point p);
/// <summary>
/// 获得窗口文字
/// </summary>
/// <param name="hWnd"></param>
/// <param name="lpString">用来保存文字的stringBuilder</param>
/// <param name="nMaxCount">stringBuilder的容量</param>
/// <returns></returns>
[DllImport("user32.dll")]
public static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString,
int nMaxCount);
public delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);
/// <summary>
/// 枚举所有控件
/// </summary>
/// <param name="lpEnumFunc"></param>
/// <param name="lParam"></param>
/// <returns></returns>
[DllImport("user32.dll")]
public static extern int EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
#endregion
#region 消息函数
//发送消息的类型（第二个参数）
public const int WM_KEYDOWN = 0X100;
public const int WM_KEYUP = 0X101;
public const int WM_CHAR = 0X102;
/// <summary>
/// 发送消息，等待返回
/// </summary>
/// <param name="hWnd">窗体句柄</param>
/// <param name="wMsg">被发送的消息类型(如键盘按下消息，字符消息等等)</param>
/// <param name="wParam">附加的消息指定信息</param>
/// <param name="lParam">附加的消息指定信息</param>
/// <returns></returns>
[DllImport("user32.dll", EntryPoint = "SendMessage", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern IntPtr SendMessage(IntPtr hWnd, int wMsg, int wParam, int lParam);
[DllImport("user32.dll", EntryPoint = "PostMessage", SetLastError = true)]
public static extern IntPtr PostMessage(IntPtr hWnd, int wMsg, int wParam, int lParam);
#endregion
#region 鼠标函数
[DllImport("user32.dll", EntryPoint = "SetCursorPos")]
internal extern static int SetCursorPos(int x, int y);
/// 使用范例： API.mouse_event(0x2 | 0x4, x,y, 0, 0); 在（x,y）处单击一下
public readonly int MOUSEEVENTF_LEFTDOWN = 0x2;
public readonly int MOUSEEVENTF_LEFTUP = 0x4;
[DllImport("user32.dll")]
public static extern void mouse_event(int dwFlags, int dx, int dy, int dwData, int dwExtraInfo);
#endregion
#region 键盘函数
public static int KEYEVENTF_EXTENDEDKEY = 0x0001;
public static int KEYEVENTF_KEYUP = 0x0002;
public static byte VK_LWIN = 0x5B;
[DllImport("user32.dll", EntryPoint = "keybd_event")]
public static extern void keybd_event(
byte bVk,
byte bScan,
int dwFlags,
int dwExtraInfo
);
#endregion
#region 自绘函数
/// <summary>
/// 获得窗口指定点处的句柄
/// </summary>
/// <param name="hwnd">主窗体句柄</param>
/// <param name="top">该点相对于主窗体上边框的距离</param>
/// <param name="left">该点相对于主窗体左边框的距离</param>
/// <returns></returns>
public static IntPtr GetWinPartFromPoint(IntPtr hwnd, int top, int left)
{
RectangleEx r = new RectangleEx();
GetWindowRect(hwnd, ref r);
//转化为整个屏幕的坐标
int topScreen = top + r.leftTopY;
int leftScreen = left + r.leftTopX;
return WindowFromPoint(new Point(topScreen, leftScreen));
}
/// <summary>
/// 到某处单击一下返回
/// </summary>
/// <param name="ox">原来的鼠标地点x</param>
/// <param name="oy"></param>
/// <param name="x">目标地点x</param>
/// <param name="y"></param>
public static void ClickPosition(int ox,int oy,int x, int y)
{
SetCursorPos(x, y);
mouse_event(0x2 | 0x4, x, y, 0, 0);
SetCursorPos(ox, oy);
}
#endregion
}