CLR via C# 读书笔记 3-1 一种单实例应用程序的实现(信号量)

单实例应用程序指的是在你的操作系统中你只能开一个的程序

例如说outlook

以下代码通过 Semaphore 实行了一个单实例的控制

(事实上你使用EventWaitHandle 或者 Mutex都是可以的)

原理是因为windows不允许重名的核心对象 ,例子中是 "SomeUniqueStringIdentifyingMyApp"

第一次调用Semaphore的时候,系统将创建一个对象并将createdNew设置为true

第二次调用Semaphore的时候,系统返回现有同名对象并将createdNew设置为false

 

using System;
using System.Threading;
public static class Program
{
    public static void Main()
    {
        Boolean createdNew;
        // Try to create a kernel object with the specified name
        using (new Semaphore(0, 1, "SomeUniqueStringIdentifyingMyApp", out createdNew))
        {
            if (createdNew)
            {
                // This thread created the kernel object so no other instance of this
                // application must be running. Run the rest of the application here...
            }
            else
            {
                // This thread opened an existing kernel object with the same string name;
                // another instance of this application must be running now.
                // There is nothing to do in here, let's just return from Main to terminate
                // this second instance of the application.
            }
        }
    }
}