采用互斥体的方法，防止程序多次运行，App.PreIntance只能判断当前目录是否有多个实例运行，本程序可以将exe拷贝到任何目录，但只能运行一个实例。-Mutex methods used to prevent the program running on many occasions, App.PreIntance only the current directory to determine whether there are multiple instances running, the program can copy the exe into any directory, but only to run a case in point.