1、服务类型的应用程序一般都是单例模式，常规是要持续运行的，平常最小化到托盘，需要查看时可以点击托盘图标最大化，但是往往操作人员会误操作，程序已经打开又去重新运行程序，以前的做法是监测是否可以创建互斥进程，如果不能则说明程序已经运行，并提示客户软件已经运行，代码如下：
//单例模式
bool bCreatedNew;
System.Threading.Mutex mutex = new System.Threading.Mutex(false, Application.ProductName, out bCreatedNew);
if (!bCreatedNew)
{
MessageBox.Show("打开失败，已有消息中心服务正在运行！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
return;
}
2、对这种方式进行改进，如果软件已经打开但是最小化到了托盘，用户再次运行软件，将隐藏在托盘里面的软件显示出来，而不是提示软件已经运行
方法一、使用FindWindow根据窗体类名或者标题获取窗体句柄（因为类名不会变化，所以优先使用类名获取），然后根据句柄显示窗体ShowWindow，让窗体获取焦点SwitchToThisWindow，然后获取窗体矩形框GetWindowRect，设置窗体显示位置SetWindowPos。
IntPtr hwnd = SingleProcess.FindWindow("WindowsForms10.Window.8.app.0.2bf8098_r11_ad1",null);
SingleProcess.ShowWin(hwnd);
获取窗体类名的方法：打开Spy++，找到“消息中心服务器”，右键属性-类 可以看到类名
方法二、开始没发现方法一，用的这种方法，获取已经运行的软件的进程，获取进程的MainWindowHandle，如果MainWindowHandle不为0（说明没有最小化）则直接根据窗口句柄显示窗体，同方法一步骤2，如果MainWindowHandle为0（由于在窗体最小化时，获取进程MainWindowHandle总是0），则枚举窗体窗体，当窗体标题与进程号满足设定值时，根据窗体句柄显示窗体。
SingleProcess.Singling("消息中心服务器");
3、完整代码：
public class SingleProcess { //根据主窗体句柄显示窗体 public static void ShowWin(IntPtr hwnd) { ShowWindow(hwnd, SW_RESTORE); SwitchToThisWindow(hwnd, true); Rect windowRec; GetWindowRect(hwnd, out windowRec); System.Drawing.Rectangle rect = System.Windows.Forms.SystemInformation.VirtualScreen; SetWindowPos(hwnd, HWND_TOP, (rect.Width - (windowRec.Right - windowRec.Left)) / 2, (rect.Height - (windowRec.Bottom - windowRec.Top)) / 2, 0, 0, SWP_NOSIZE); } private static string _formText;// = string.Empty; private static Process _process = null; /// <summary> /// /// </summary> /// <param name="str"></param> public static void Singling(string formtext) { _formText = formtext; Process instance = GetInstance(); if (instance != null) //首先确定有无进程 { _process = instance; if (_process.MainWindowHandle.ToInt32() != 0) //是否托盘化 { //HandleRunningInstance(pro); ShowWin(_process.MainWindowHandle); } else { CallBack myCallBack = new CallBack(Report); EnumWindows(myCallBack, 0); } //System.Environment.Exit(System.Environment.ExitCode); } } public static Process GetInstance() { Process current = Process.GetCurrentProcess(); Process[] processes = Process.GetProcessesByName(Application.ProductName);//current.ProcessName); //遍历正在有相同名字运行的例程 foreach (Process process in processes) { //忽略现有的例程 if (process.Id != current.Id) { //if (process.MainModule.FileName == current.MainModule.FileName) { //返回另一个例程实例 return process; } } } //没有其它的例程，返回Null return null; } private static bool Report(IntPtr hwnd, int lParam) { //获得窗体标题 StringBuilder sb = new StringBuilder(100); GetWindowText(hwnd, sb, sb.Capacity); int calcID; //获取进程ID GetWindowThreadProcessId(hwnd, out calcID); if ((sb.ToString() == _formText) && (_process != null) && (calcID == _process.Id)) //标题栏、进程id符合 //if (pro != null && calcID == pro.Id) //进程id符合 { ShowWin(hwnd); return true; } return true; } #region win32 API /// <summary> /// 获取窗体句柄 /// </summary>，两个参数至少要知道一个 /// <param name="lpClassName">窗体类名，可以通过Spy++获取，为null表示忽略</param> /// <param name="lpWindowName">窗体标题，Text属性，为null时表示忽略</param> /// <returns></returns> [DllImport("user32.dll", EntryPoint = "FindWindow")] public extern static IntPtr FindWindow(string lpClassName, string lpWindowName); /// <summary> /// 根据窗体句柄获得窗体标题 /// </summary> /// <param name="hWnd"></param> /// <param name="lpText"></param> /// <param name="nCount"></param> /// <returns></returns> [DllImport("user32.dll", CharSet = CharSet.Auto)] private static extern int GetWindowText(IntPtr hWnd, StringBuilder lpText, int nCount); /// <summary> /// 枚举窗体 /// </summary> /// <param name="x"></param> /// <param name="y"></param> /// <returns></returns> [DllImport("user32")] private static extern int EnumWindows(CallBack x, int y); private delegate bool CallBack(IntPtr hwnd, int lParam); /// <summary> /// 根据窗体句柄获得其进程ID /// </summary> /// <param name="hwnd"></param> /// <param name="ID"></param> /// <returns></returns> [DllImport("User32.dll", CharSet = CharSet.Auto)] private static extern int GetWindowThreadProcessId(IntPtr hwnd, out int ID); /// <summary> /// 修改位置、大小 /// </summary> /// <param name="hWnd"></param> /// <param name="hWndInsertAfter"></param> /// <param name="X"></param> /// <param name="Y"></param> /// <param name="cx"></param> /// <param name="cy"></param> /// <param name="uFlags"></param> /// <returns></returns> [DllImport("user32.dll")] private static extern bool SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags); /// <summary> /// Retains the current size (ignores the cx and cy parameters). /// </summary> static uint SWP_NOSIZE = 0x0001; static int HWND_TOP = 0; public struct Rect { public int Left; public int Top; public int Right; public int Bottom; } [DllImport("user32.dll")] private static extern int GetWindowRect(IntPtr hwnd, out Rect lpRect); /// <summary> /// 显示窗体,同 ShowWindowAsync 差不多 /// </summary> /// <param name="hwnd"></param> /// <param name="nCmdShow"></param> /// <returns></returns> [DllImport("user32.dll", EntryPoint = "ShowWindow", CharSet = CharSet.Auto)] private static extern int ShowWindow(IntPtr hwnd, int nCmdShow); private const int SW_RESTORE = 9; /// <summary> /// 该函数设置由不同线程产生的窗口的显示状态。 (没用) /// </summary> /// <param name="hWnd">窗口句柄</param> /// <param name="cmdShow">指定窗口如何显示。查看允许值列表，请查阅ShowWlndow函数的说明部分。</param> /// <returns>如果函数原来可见，返回值为非零；如果函数原来被隐藏，返回值为零。</returns> [DllImport("User32.dll")] private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow); /// <summary> /// 该函数将创建指定窗口的线程设置到前台，并且激活该窗口。 /// 键盘输入转向该窗口，并为用户改各种可视的记号。系统给创建前台窗口的线程分配的权限稍高于其他线程。 /// (没用) /// </summary> /// <param name="hWnd">将被激活并被调入前台的窗口句柄。</param> /// <returns>如果窗口设入了前台，返回值为非零；如果窗口未被设入前台，返回值为零。</returns> [DllImport("User32.dll")] private static extern bool SetForegroundWindow(IntPtr hWnd); private const int WS_SHOWNORMAL = 1; /// <summary> /// 窗体焦点 /// </summary> /// <param name="hWnd"></param> /// <param name="fAltTab"></param> [DllImport("user32.dll ", SetLastError = true)] private static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab); #endregion }
4、调用
//单例模式 bool bCreatedNew; System.Threading.Mutex mutex = new System.Threading.Mutex(false, Application.ProductName, out bCreatedNew); if (!bCreatedNew) { tempForm.Close(); IntPtr hwnd = SingleProcess.FindWindow("WindowsForms10.Window.8.app.0.2bf8098_r11_ad1",null); SingleProcess.ShowWin(hwnd); //SingleProcess.Singling("消息中心服务器"); //MessageBox.Show("打开失败，已有消息中心服务正在运行！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information); return; }
.参考
http://www.cnblogs.com/qingse/archive/2013/02/16/2913430.html
