單例模式用于限制進程中只有一個某個類的對象，本例的Singleton是一個線程實例，在每一個時鐘到達時檢測是否到達某個時刻（本例的時刻存于Ini文件中），如果到達則產生一個線程，但是如果在這個線程完成其任務前又到達一個時鐘，則有可能會產生多個線程執行任務，以致出現混亂，所以考慮使用Singleton模式解決這個問題（當然還有其他解決方案，但本例使用的是Singleton）。 核心代碼如下： //timer單元 PRocedure TService1.Timer_mainTimer(Sender: TObject); var mystringlist:TStringList; SearchRec: TSearchRec; nowtime :string; begin try DateTimeToString(nowtime,'hh:nn',now); if LeftStr(nowtime,4)=LeftStr(GetMSG('GAME','下發時間',theexename+'.ini'),4) then begin //創建發送線程 Global_Instance:=TSendThread.getInstance; ////////////// end; except on e: Exception do begin mystringlist:=TStringList.Create; if FileExists(ExtractFilePath(Paramstr(0))+'Err.txt') then mystringlist.LoadFromFile(ExtractFilePath(Paramstr(0))+'Err.txt'); mystringlist.Add('('+DateTimeToStr(Now)+')[創建線程出錯:]'+E.Message); mystringlist.SaveToFile(ExtractFilePath(Paramstr(0))+'Err.txt'); mystringlist.Free; if FindFirst(ExtractFilePath(Paramstr(0))+'Err.txt', faAnyFile, SearchRec)=0 then begin if SearchRec.Size>5000000 then begin RenameFile(ExtractFilePath(Paramstr(0))+'Err.txt',ansireplacestr(ExtractFilePath(Paramstr(0))+'Err.txt','.txt',FormatDateTime('yyyy-MM-dd hh-mm-ss',now)+'.txt')); end; end; end; end; end; //線程單元 unit Unit_Send ;
interface uses SysUtils, Classes,StrUtils,main; type TSendThread = class(TThread) public constructor Create(CreateSuspended: Boolean); destructor Destroy; override; class function getInstance:TSendThread; procedure joke;
protected procedure Execute; override; end;
var Global_Instance:TSendThread;
implementation
uses DB;
class function TSendThread.getInstance:TSendThread; begin if Global_Instance=nil then begin Global_Instance:=TSendThread.Create(false); end; Result:=Global_Instance; end; constructor TSendThread.Create(CreateSuspended: Boolean); begin if Global_Instance=nil then begin inherited Create(CreateSuspended); FreeOnTerminate:=true ; end else raise Exception.CreateFmt('Can not create more than one TSendThread instance!',[SysErrorMessage(0)]); end; destructor TSendThread.Destroy; begin inherited Destroy; end; procedure TSendThread.joke; begin end; procedure TSendThread.Execute; var theuser:TUserInfo; tmpSql:string; begin //執行任務 //處理定時下發 '+GameInfo.mainusertable+' tmpSql:='select * from '+mainusertable+' where destroy=0 order by id'; Service1.ADOQuery_send.Connection:=conn_Server; SQLQuery(Service1.ADOQuery_send,tmpSql); while (not Service1.ADOQuery_send.Eof) and (not Terminated) do begin theuser.SeqID:='0'; theuser.UID:=''; theuser.Spc:=GetMSG('PARAMETER','Spcode',theexename+'.ini'); theuser.RecordID:='0'; theuser.Mob:=Service1.ADOQuery_send.FieldByname('mobile').AsString; AutoJoke(theuser); Service1.ADOQuery_send.Next; end; Sleep(600001); Global_Instance:=nil; Terminate; //任務完成 end; end.
