Question

c#中让Windows窗体只运行一次，并在第二次启动窗体时激活该窗体

不是MDI窗体，就一个单独的窗体
就像迅雷一样 迅雷在启动的时候点击关闭按钮就最小化到电脑的右下角了，然后在启动迅雷，却没有从新启动，而是把已经启动的迅雷激活了...请问用C#怎么实现。

Answer 1

方法一:

/// <summary>
/// 从这里开始运行
/// </summary>
[STAThread]
static void Main()
{
Process instance = RunningInstance();
if (instance == null)
{
//没有实例在运行
WeatherApp appInstance = new WeatherApp();
appInstance.StartMainGui();
}
else
{
//已经有一个实例在运行
HandleRunningInstance(instance);
}
}
#region 确保只有一个实例
public static Process RunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);
//遍历与当前进程名称相同的进程列表
foreach (Process process in processes)
{
//Ignore the current process
if (process.Id != current.Id)
{
//Make sure that the process is running from the exe file.
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
{
//Return the other process instance.
return process;
}
}
}
return null;
}
private static void HandleRunningInstance(Process instance)
{
MessageBox.Show("该应用系统已经在运行！", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Information);
ShowWindowAsync(instance.MainWindowHandle, 1); //调用api函数，正常显示窗口
SetForegroundWindow(instance.MainWindowHandle); //将窗口放置最前端。
}
[DllImport("User32.dll")]
private static extern bool ShowWindowAsync(System.IntPtr hWnd, int cmdShow);
[DllImport("User32.dll")]
private static extern bool SetForegroundWindow(System.IntPtr hWnd);
#endregion

方法二:

[STAThread]
static void Main(string[] args)
{
bool isFirst;

System.Threading.Mutex mutex = new System.Threading.Mutex(true, "WindowAppTest", out isFirst);
//这里的myApp是程序的标识,建议换成你的程序的物理路径,这样的话如果在一个操作系统中这个标志不会和其它程序冲突
if (!isFirst)
{
MessageBox.Show("Exist");
Environment.Exit(1);//实例已经存在,退出程序
}
else
{
Application.Run(new Form1());
}
}

方法三
把AssemblyInfo.cs里的[assembly: AssemblyFileVersion("1.0.0.0")]改为[assembly:AssemblyFileVersion("2.0.0.8")]，然后利用该信息进行判断。
代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Reflection;
using System.Collections;
using System.Threading;

namespace MyWork_01
{
class Program
{
static void Main(string[] args)
{
Process[] processes = Process.GetProcesses(); //获得当前所有进程
Process currentProcess = Process.GetCurrentProcess(); //获取当前正在运行进程
ProcessModule currentPM = currentProcess.Modules[0];
int same = 0; //相同运行实例个数
ArrayList proList = new ArrayList(); //将相同实例加入此集合中

foreach (Process p in processes)
{
try//由于进程不同，有的进程不包含Modules信息，所以要用try保护
{
if (p.Modules != null)
if (p.Modules.Count > 0)
{
System.Diagnostics.ProcessModule pm = p.Modules[0];
if (pm.FileVersionInfo.FileVersion.Equals(currentPM.FileVersionInfo.FileVersion))
{
same++;
proList.Add(p);
}
if (same > 1)
{
same++;
proList.Add(p);
if (same > 1)
{
for (int i = 0; i < proList.Count; i++)
{
if (((Process)(proList[i])).Id == currentProcess.Id)
{
Console.WriteLine("该进程已经启动了一个实例");
Thread.Sleep(1000);
((Process)(proList[i])).Kill();
}
}
}
}
}
}
catch
{ }
}
Console.Read();
}
}
}

方法四：直接定义一个属性类，利用此属性信息进行判断。
代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Diagnostics;
using System.Collections;
using System.Threading;

[assembly: Help("This Assembly demonstrates custom attributes creation and their run-time query.")]

public class HelpAttribute : Attribute
{
public HelpAttribute(String Description_in)
{
this.description = Description_in;
}

protected String description;

public String Description
{
get
{
return this.description;
}
}
}
class Program
{
static void Main(string[] args)
{
HelpAttribute HelpAttr1 = null;
HelpAttribute HelpAttr2 = null;
Process currentProcess = Process.GetCurrentProcess(); //获取当前正在运行进程
Assembly a = Assembly.LoadFrom(currentProcess.MainModule.FileName);
foreach (Attribute attr in a.GetCustomAttributes(true))
{
HelpAttr1 = attr as HelpAttribute;
if (null != HelpAttr1)
{
//Console.WriteLine("Description of {0}:\n{1}", currentProcess.MainModule.FileName, HelpAttr1.Description);
break;
}
}
Process[] processes = Process.GetProcesses(); //获得当前所有进程
int same = 0; //相同运行实例个数
ArrayList proList = new ArrayList(); //将相同实例加入此集合中
foreach (Process pro in processes)
{
try//由于进程不同，有的进程不包含Modules信息，所以要用try保护
{
if (pro.Modules != null)
if (pro.Modules.Count > 0)
{
Assembly b = Assembly.LoadFrom(pro.MainModule.FileName);
foreach (Attribute attr in b.GetCustomAttributes(true))
{
HelpAttr2 = attr as HelpAttribute;
if (null != HelpAttr2)
{
if (HelpAttr1.Description.Equals(HelpAttr2.Description))
{
same++;
proList.Add(pro);
if (same > 1)
{
for (int i = 0; i < proList.Count; i++)
{
if (((Process)(proList[i])).Id == currentProcess.Id )
{
Console.WriteLine("该进程已经启动了一个实例");

Thread.Sleep(1000);
((Process)(proList[i])).Kill();

}
}
}
}
}
}
}
}
catch
{
}
}
Console.ReadLine();
}

}

Answer 2

点下面有个 激活MDI就好了