C#
using System.Reflection;
using System.Runtime.InteropServices;
namespace 防止程序二次运行
{
static class Program
{
[DllImport("user32.dll")]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
/// <summary>
/// 该函数设置由不同线程产生的窗口的显示状态。
/// </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 ShowWindow(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。
/// </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 SW_SHOWNORMAL = 1;
/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Process processes = RunningInstance();
if (processes == null)
{
Application.Run(new FrmMain());
}
else
{
HandleRunningInstance(processes);
}
}
/// <summary>
/// 获取正在运行的实例，没有运行的实例返回null;
/// </summary>
public static Process RunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);
foreach (Process process in processes)
{
if (process.Id != current.Id)
{
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
{
return process;
}
}
}
return null;
}
/// <summary>
/// 显示已运行的程序。
/// </summary>
public static void HandleRunningInstance(Process instance)
{
try
{
IntPtr formHwnd = FindWindow(null, "程序主窗口标题");
ShowWindow(formHwnd, SW_SHOWNORMAL); //显示
SetForegroundWindow(formHwnd); //放到前端
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}
}
VB.NET
Imports System.Runtime.InteropServices
Imports System.Reflection
Namespace 防止程序重复运行
Module Program
<DllImport("user32.dll")> _
Public Function FindWindow(lpClassName As String, lpWindowName As String) As IntPtr
End Function
''' <summary>
''' 该函数设置由不同线程产生的窗口的显示状态。
''' </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 Function ShowWindow(hWnd As IntPtr, cmdShow As Integer) As Boolean
End Function
''' <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。
''' </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 Function SetForegroundWindow(hWnd As IntPtr) As Boolean
End Function
Private Const SW_SHOWNORMAL As Integer = 1
''' <summary>
''' 应用程序的主入口点。
''' </summary>
<STAThread> _
Sub Main()
Application.EnableVisualStyles()
Application.SetCompatibleTextRenderingDefault(False)
Dim processes As Process = RunningInstance()
If processes Is Nothing Then
Application.Run(New FrmMain())
Else
HandleRunningInstance(processes)
End If
End Sub
''' <summary>
''' 获取正在运行的实例，没有运行的实例返回null;
''' </summary>
Public Function RunningInstance() As Process
Dim current As Process = Process.GetCurrentProcess()
Dim processes As Process() = Process.GetProcessesByName(current.ProcessName)
For Each process As Process In processes
If process.Id <> current.Id Then
If Assembly.GetExecutingAssembly().Location.Replace("/", "\") = current.MainModule.FileName Then
Return process
End If
End If
Next
Return Nothing
End Function
''' <summary>
''' 显示已运行的程序。
''' </summary>
Public Sub HandleRunningInstance(instance As Process)
Try
Dim formHwnd As IntPtr = FindWindow(Nothing, "程序主窗口标题")
ShowWindow(formHwnd, SW_SHOWNORMAL)
'显示
'放到前端
SetForegroundWindow(formHwnd)
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
End Module
End Namespace
