Windows获取系统当前时区的两种方法

获取本地时区方法
本文介绍了两种在Windows环境下获取本地时区的方法:一种是使用C++实现,通过调用Windows API函数GetTimeZoneInformation;另一种是使用C语言实现,通过获取当前时间和格林尼治标准时间的差值来计算。

1、Windows c++ 方法

#include <atltime.h>
#include <Windows.h>
int CTimeRyan::GetLocalTimeZoneByCPP()
{
	TIME_ZONE_INFORMATION tmp;
	GetTimeZoneInformation(&tmp);

	return tmp.Bias/(-60);
}


2、Windows c 方法

#include <cstdlib>
#include <stdio.h>
#include <time.h>
int CTimeRyan::GetLocalTimeZoneByC()
{
	time_t time_utc;  
	struct tm tm_local;  

	// Get the UTC time  
	time(&time_utc);  

	// Get the local time  
	// Use localtime_r for threads safe for linux 
	//localtime_r(&time_utc, &tm_local);
	localtime_s(&tm_local, &time_utc);

	time_t time_local;  
	struct tm tm_gmt;  

	// Change tm to time_t   
	time_local = mktime(&tm_local);  

	// Change it to GMT tm
	//gmtime_r(&time_utc, &tm_gmt);//linux
	gmtime_s(&tm_gmt, &time_utc);  

	int time_zone = tm_local.tm_hour - tm_gmt.tm_hour;  
	if (time_zone < -12) {  
		time_zone += 24;   
	} else if (time_zone > 12) {  
		time_zone -= 24;  
	}  

	return time_zone;
}


unit uTimeZonesMgr; interface uses Windows, SysUtils, Classes, Registry, DateUtils; type {* 用于读取时区注册表TZI(长度为44)的属性值,存储时区信息 *} PRegTZIInfo = ^TRegTZIInfo; TRegTZIInfo = record Bias: Longint; StandardBias: Longint; DaylightBias: Longint; StandardDate: TSystemTime; DaylightDate: TSystemTime; end; {* 单个时区管理对象 *} TTimeZone = class private FTimeZoneName: string; //时区的显示名 FDisplay: string; //夏令时的名字 FDlt: string; //时区标准名字 FStd: string; //是Time zone information的缩写,描述时区的一些重要信息 FTZI: PRegTZIInfo; function GetSelfTimeZoneInformation: TTimeZoneInformation; public constructor Create; destructor Destroy; override; function UTCToLocalDateTime(const AUTC: TDateTime; var ALocalDateTime: TDateTime): Boolean; function LocalDateTimeToUTC(const ALocalDateTime: TDateTime; var AUTC: TDateTime): Boolean; public property TimeZoneName: string read FTimeZoneName write FTimeZoneName; property Display: string read FDisplay write FDisplay; property Dlt: string read FDlt write FDlt; property Std: string read FStd write FStd; property TZI: PRegTZIInfo read FTZI write FTZI; end; {* 所有时区管理对象 *} TTimeZones = class private FTimeZoneKeyPath: string; FTimeZoneList: TStringList; FDefaultTimeZone: TTimeZone; procedure CollectTimeZone; procedure DestoryTimeZones; procedure CheckISDefaultTimeZone(ATimeZone: TTimeZone); public constructor Create; destructor Destroy; override; function FindTimeZone(const ADisplay: string): TTimeZone; public property TimeZoneList: TStringList read FTimeZoneList; property DefaultTimeZone: TTimeZone read FDefaultTimeZone; end; implementation { TTimeZones } procedure TTimeZones.CheckISDefaultTimeZone(ATimeZone: TTimeZone); var DefaultTimeZone: TTimeZoneInformation; begin GetTimeZoneInformation(DefaultTimeZone); if (ATimeZone.TZI.Bias = DefaultTimeZone.Bias) and (ATimeZone.Std = DefaultTimeZone.StandardName) then FDefaultTimeZone := ATimeZone; end; procedure TTimeZones.CollectTimeZone; var reg, tempReg: TRegistry; tempKeyPath: string; tempTimeZoneStrings: TStrings; iCir: Integer; tempTimeZone: TTimeZone; begin reg := TRegistry.Create; try reg.RootKey := HKEY_LOCAL_MACHINE; reg.OpenKey(FTimeZoneKeyPath, False); tempTimeZoneStrings := TStringList.Create; try reg.GetKeyNames(tempTimeZoneStrings); for iCir := 0 to tempTimeZoneStrings.Count - 1 do begin tempKeyPath := FTimeZoneKeyPath + '\' + tempTimeZoneStrings.Strings[iCir]; tempReg := TRegistry.Create; try tempReg.RootKey := HKEY_LOCAL_MACHINE; tempReg.OpenKey(tempKeyPath, False); tempTimeZone := TTimeZone.Create; tempTimeZone.TimeZoneName := tempTimeZoneStrings.Strings[iCir]; tempTimeZone.Display := tempReg.ReadString('Display'); tempTimeZone.Std := tempReg.ReadString('Std'); tempTimeZone.Dlt := tempReg.ReadString('Dlt'); tempReg.ReadBinaryData('TZI', tempTimeZone.TZI^, SizeOf(TRegTZIInfo)); FTimeZoneList.AddObject(tempTimeZone.Display, tempTimeZone); if FDefaultTimeZone = nil then CheckISDefaultTimeZone(tempTimeZone); finally tempReg.CloseKey; tempReg.Free; end; end; finally tempTimeZoneStrings.Free; end; finally reg.CloseKey; reg.Free; end; end; constructor TTimeZones.Create; begin FTimeZoneKeyPath := '\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones'; FTimeZoneList := TStringList.Create; FTimeZoneList.Sorted := True; FDefaultTimeZone := nil; CollectTimeZone; end; procedure TTimeZones.DestoryTimeZones; var iCir: Integer; tempTimeZone: TTimeZone; begin for iCir := 0 to FTimeZoneList.Count - 1 do begin tempTimeZone := TTimeZone(FTimeZoneList.Objects[iCir]); tempTimeZone.Free; end; FTimeZoneList.Clear; FTimeZoneList.Free; end; destructor TTimeZones.Destroy; begin DestoryTimeZones(); inherited; end; function TTimeZones.FindTimeZone(const ADisplay: string): TTimeZone; var iIndex: Integer; begin Result := nil; FTimeZoneList.Sort; if FTimeZoneList.Find(ADisplay, iIndex) then begin Result := TTimeZone(FTimeZoneList.Objects[iIndex]); end; end; { TTimeZone } constructor TTimeZone.Create; begin FTZI := GetMemory(SizeOf(TRegTZIInfo)); FillMemory(FTZI, SizeOf(TRegTZIInfo), 0); end; destructor TTimeZone.Destroy; begin FreeMemory(FTZI); inherited; end; function TTimeZone.GetSelfTimeZoneInformation: TTimeZoneInformation; begin GetTimeZoneInformation(Result); Result.Bias := TZI^.Bias; Result.StandardBias := TZI^.StandardBias; Result.StandardDate := TZI^.StandardDate; Result.DaylightBias := TZI^.DaylightBias; Result.DaylightDate := TZI^.DaylightDate; end; function TTimeZone.LocalDateTimeToUTC(const ALocalDateTime: TDateTime; var AUTC: TDateTime): Boolean; var tempLocalToLocal: TDateTime; iMilliSecond: Int64; begin Result := UTCToLocalDateTime(ALocalDateTime, tempLocalToLocal); if Result then begin if tempLocalToLocal > ALocalDateTime then begin iMilliSecond := MilliSecondsBetween(tempLocalToLocal, ALocalDateTime); AUTC := IncMilliSecond(ALocalDateTime, iMilliSecond * -1); end else begin iMilliSecond := MilliSecondsBetween(ALocalDateTime, tempLocalToLocal); AUTC := IncMilliSecond(ALocalDateTime, iMilliSecond); end; Result := True; end; end; function TTimeZone.UTCToLocalDateTime(const AUTC: TDateTime; var ALocalDateTime: TDateTime): Boolean; var TimeZone: TTimeZoneInformation; stUTC, stLC: SYSTEMTIME; begin Result := False; TimeZone := GetSelfTimeZoneInformation; DateTimeToSystemTime(AUTC, stUTC); if SystemTimeToTzSpecificLocalTime(@TimeZone, stUTC, stLC) then begin ALocalDateTime := SystemTimeToDateTime(stLC); Result := True; end; end; end.
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