///////////////////// （一）项目文件 test.dpr //////////////////////
program SerialGet;
uses
Forms,
UMain in 'UMain.pas' {frmMain},
ULogin in 'UForm2.pas' {Form2},
UDataModule in 'UDataModule.pas' {DataModule1: TDataModule},
{$R *.res}
begin
Application.Initialize;
if CreateMutex then //创建句柄，判断此应用程序是否在运行
begin
Application.CreateForm(TfrmMain, frmMain);
Application.CreateForm(Tform2, form2);
Application.CreateForm(TDataModule1, DataModule1);
Application.Run;
end else
begin
DestroyMutex; //释放句柄
end;
end.
//////////////// （二）登陆窗体 UMain.pas UMain.dfm //////////////////
unit UMain;
interface
uses ......
type
... ... ...
private
public
end;
var
frmMain: TfrmMain;
function CreateMutex: Boolean; // 全项目公用函数
procedure DestroyMutex; // 全项目公用函数
implementation
uses UDataModule; //引用数据模块
var Mutex: hWnd;
{$R *.dfm}
procedure DestroyMutex;
begin
if Mutex <> 0 then CloseHandle(Mutex);
end;
function CreateMutex: Boolean;
var
PrevInstHandle: THandle;
AppTitle: PChar;
begin
AppTitle := StrAlloc(100);
StrPCopy(AppTitle, Application.Title);
Result := True;
Mutex := Windows.CreateMutex(nil, False, AppTitle);
if (GetLastError = ERROR_ALREADY_EXISTS) or (Mutex = 0) then begin
Result := False;
SetWindowText(Application.Handle, '');
PrevInstHandle := FindWindow(nil, AppTitle);
if PrevInstHandle <> 0 then begin
if IsIconic(PrevInstHandle) then
ShowWindow(PrevInstHandle, SW_RESTORE)
else
BringWindowToTop(PrevInstHandle);
SetForegroundWindow(PrevInstHandle);
end;
if Mutex <> 0 then Mutex := 0;
end;
StrDispose(AppTitle);
end;