最近在做winform的程序中,需要只能打開一個程序,如果已經存在,則激活該程序的窗口,並顯示在最前端。在網上google了一哈,找到了很多的解決方案。這里我整理了3種方案,並經過了測試,現和朋友們分享:
一、使用用互斥量(System.Threading.Mutex)
同步基元,它只向一個線程授予對共享資源的獨占訪問權。在程序啟動時候,請求一個互斥體,如果能獲取對指定互斥的訪問權,就職運行一個實例。

bool createNew;
using (System.Threading.Mutex mutex = new System.Threading.Mutex(true, Application.ProductName, out createNew))
{
if (createNew)
{
Application.Run(new Form1());
}
else
{
MessageBox.Show("應用程序已經在運行中...")
using (System.Threading.Mutex mutex = new System.Threading.Mutex(true, Application.ProductName, out createNew))
{
if (createNew)
{
Application.Run(new Form1());
}
else
{
MessageBox.Show("應用程序已經在運行中...")
System.Threading.Thread.Sleep(1000);
System.Environment.Exit(1);
}
}
System.Environment.Exit(1);
}
}
二、使用進程名

Process[] processes = System.Diagnostics.Process.GetProcessesByName(Application.CompanyName);
if (processes.Length > 1)
{
MessageBox.Show("應用程序已經在運行中。。");
Thread.Sleep(1000);
System.Environment.Exit(1);
}
else
{
Application.Run(new Form1());
}
if (processes.Length > 1)
{
MessageBox.Show("應用程序已經在運行中。。");
Thread.Sleep(1000);
System.Environment.Exit(1);
}
else
{
Application.Run(new Form1());
}
三、調用Win32 API,並激活並程序的窗口,顯示在最前端

/// 該函數設置由不同線程產生的窗口的顯示狀態
/// </summary>
/// <param name="hWnd">窗口句柄</param>
/// <param name="cmdShow">指定窗口如何顯示。查看允許值列表,請查閱ShowWlndow函數的說明部分</param>
/// <returns>如果函數原來可見,返回值為非零;如果函數原來被隱藏,返回值為零</returns>
[DllImport("User32.dll")]
private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
/// <summary>
/// 該函數將創建指定窗口的線程設置到前台,並且激活該窗口。鍵盤輸入轉向該窗口,並為用戶改各種可視的記號。
/// 系統給創建前台窗口的線程分配的權限稍高於其他線程。
/// </summary>
/// <param name="hWnd">將被激活並被調入前台的窗口句柄</param>
/// <returns>如果窗口設入了前台,返回值為非零;如果窗口未被設入前台,返回值為零</returns>
[DllImport("User32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);
/// </summary>
/// <param name="hWnd">窗口句柄</param>
/// <param name="cmdShow">指定窗口如何顯示。查看允許值列表,請查閱ShowWlndow函數的說明部分</param>
/// <returns>如果函數原來可見,返回值為非零;如果函數原來被隱藏,返回值為零</returns>
[DllImport("User32.dll")]
private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
/// <summary>
/// 該函數將創建指定窗口的線程設置到前台,並且激活該窗口。鍵盤輸入轉向該窗口,並為用戶改各種可視的記號。
/// 系統給創建前台窗口的線程分配的權限稍高於其他線程。
/// </summary>
/// <param name="hWnd">將被激活並被調入前台的窗口句柄</param>
/// <returns>如果窗口設入了前台,返回值為非零;如果窗口未被設入前台,返回值為零</returns>
[DllImport("User32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);

private const int SW_SHOWNOMAL = 1;
private static void HandleRunningInstance(Process instance)
{
ShowWindowAsync(instance.MainWindowHandle, SW_SHOWNOMAL);//顯示
SetForegroundWindow(instance.MainWindowHandle);//當到最前端
}
private static Process RuningInstance()
{
Process currentProcess = Process.GetCurrentProcess();
Process[] Processes = Process.GetProcessesByName(currentProcess.ProcessName);
foreach (Process process in Processes)
{
if (process.Id != currentProcess.Id)
{
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == currentProcess.MainModule.FileName)
{
return process;
}
}
}
return null;
}
private static void HandleRunningInstance(Process instance)
{
ShowWindowAsync(instance.MainWindowHandle, SW_SHOWNOMAL);//顯示
SetForegroundWindow(instance.MainWindowHandle);//當到最前端
}
private static Process RuningInstance()
{
Process currentProcess = Process.GetCurrentProcess();
Process[] Processes = Process.GetProcessesByName(currentProcess.ProcessName);
foreach (Process process in Processes)
{
if (process.Id != currentProcess.Id)
{
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == currentProcess.MainModule.FileName)
{
return process;
}
}
}
return null;
}

Process process = RuningInstance();
if (process == null)
{
Application.Run(new Form1());
}
else
{
MessageBox.Show("應用程序已經在運行中。。。");
if (process == null)
{
Application.Run(new Form1());
}
else
{
MessageBox.Show("應用程序已經在運行中。。。");
HandleRunningInstance(process);
//System.Threading.Thread.Sleep(1000);
//System.Environment.Exit(1);
}
//System.Threading.Thread.Sleep(1000);
//System.Environment.Exit(1);
}