///////////////////// （一）项目文件 test.dpr //////////////////////
program serialget;
uses
forms,
umain in 'umain.pas' {frmmain},
ulogin in 'ulogin.pas' {frmlogin},
udatamodule in 'udatamodule.pas' {datamodule1: tdatamodule},
{$r *.res}
begin
application.initialize;
if createmutex then //创建句柄，判断此应用程序是否在运行
begin
//调用全局函数，创建并显示登陆界面
if dologin then //登陆成功
begin
application.createform(tfrmmain, frmmain);
//数据模块文件不须在这儿创建，因为 ulogin.pas 中已创建
//application.createform(tdatamodule1, datamodule1);
application.run;
end else //登陆不成功
begin
try
datamodule1.free;
application.terminate;
except
end;
end;
end else
begin
destroymutex; //释放句柄
end;
end.
//////////////// （二）登陆窗体 ulogin.pas ulogin.dfm //////////////////
unit ulogin;
interface
uses ......
type
... ... ...
private
function checkpsw:integer;
public
end;
var
frmlogin: tfrmlogin;
function dologin:boolean; // 全项目公用函数
function createmutex: boolean; // 全项目公用函数
procedure destroymutex; // 全项目公用函数
implementation
uses udatamodule; //引用数据模块
var mutex: hwnd;
{$r *.dfm}
function dologin:boolean; //由项目文件调用此函数
begin
with tfrmlogin.create(application) do //创建并显示登陆界面
begin
//窗体的showmodal属性
if showmodal = mrok then result := true else result := false;
free;
end;
end;
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;
// -1: 密码不对 1:数据库不对 2:没有此用户 3:合法
function tfrmlogin.checkpsw:integer;
var name,spsw,sql,svalue:string;
begin
application.createform(tdatamodule1, datamodule1); //此处创建了数据模块
if not datamodule1.connok then
