程序只允许运行一个实例的三种例子

一：互斥体

program test;
uses
  Windows;

var
    MutexHandle: Longword;

begin
  if OpenMutex(MUTEX_ALL_ACCESS, FALSE, 'test')=0 then
  begin
    MutexHandle := CreateMutex(nil,TRUE,'test'); //创建一个互斥体，禁止重复运行
    MessageBox(0, pchar('try run another?'), pchar('It Works'), 0);
    ReleaseMutex(MutexHandle);                                //关闭互斥体
  end;
end.

异常退出了，互斥体还不消失

二：全局原子

program test;

Uses Windows

const iAtom=‘SingleApp’;

begin
　if GlobalFindAtom(iAtom)=0 then
　begin
　　 GlobalAddAtom(iAtom);
        MessageBox(0, pchar('only 1'), pchar('It Works'), 0);
　　 GlobalDeleteAtom(GlobalFindAtom(iAtom));
　end;
end.

三：内存影射

除了能保存全局变量，还可以唯一标志，但异常退出的话也不能消失

program test;

Uses Windows

var
  hMappingFile: THandle;
  PShared: ^TShared;

begin
     hMappingFile := OpenFileMapping(FILE_MAP_READ, False, 'test');
     if hMappingFile = 0 then
     begin
        hMappingFile := CreateFileMapping($FFFFFFFF, nil, PAGE_READWRITE, 0, SizeOf(TShared), 'test');
        PShared := MapViewOfFile(hMappingFile, FILE_MAP_WRITE or FILE_MAP_READ, 0, 0, 0);
        MessageBox(0, pchar('the one'), pchar('It Works'), 0); 
        UnmapViewOfFile(PShared);
       CloseHandle(hMappingFile);
　 end;
end.
 

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