utc时间日期android,如何将UTC时间戳转换为android中的设备本地时间

这篇博客探讨了如何正确处理服务器返回的UTC时间戳,并与本地系统时间进行比较。通过使用Calendar和SimpleDateFormat,可以校验时间戳是否符合预期的日期,并计算时间差。如果服务器时间戳不是UTC,将会导致时间差异不准确。文章提供了调试和验证时间戳的代码示例。

您的示例中的代码乍一看看起来很好。顺便说一句,如果服务器时间戳是UTC(即它是一个纪元时间戳),那么你不必应用当前时区偏移量。换句话说,如果服务器时间戳是UTC格式,那么您可以简单地获取服务器时间戳和系统时间之间的差异(System.currentTimeMillis()),因为系统时间是UTC(纪元)。

我会检查来自服务器的时间戳是否符合预期。如果服务器的时间戳未转换为您期望的日期(在本地时区中),则时间戳与当前系统时间之间的差异将不是您所期望的。

使用Calendar获取当前时区。使用当前时区初始化SimpleDateFormatter;然后记录服务器时间戳并验证它是否是您期望的日期:

Calendar cal = Calendar.getInstance();

TimeZone tz = cal.getTimeZone();

/* debug: is it local time? */

Log.d("Time zone: ", tz.getDisplayName());

/* date formatter in local timezone */

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");

sdf.setTimeZone(tz);

/* print your timestamp and double check it's the date you expect */

long timestamp = cursor.getLong(columnIndex);

String localTime = sdf.format(new Date(timestamp * 1000)); // I assume your timestamp is in seconds and you're converting to milliseconds?

Log.d("Time: ", localTime);如果打印的服务器时间不是您所期望的,那么您的服务器时间不是UTC。

如果打印的服务器时间是您期望的日期,那么您不必将rawoffset应用于它。所以你的代码会更简单(减去所有调试日志记录):

long timestamp = cursor.getLong(columnIndex);

Log.d("Server time: ", timestamp);

/* log the device timezone */

Calendar cal = Calendar.getInstance();

TimeZone tz = cal.getTimeZone();

Log.d("Time zone: ", tz.getDisplayName());

/* log the system time */

Log.d("System time: ", System.currentTimeMillis());

CharSequence relTime = DateUtils.getRelativeTimeSpanString(

timestamp * 1000,

System.currentTimeMillis(),

DateUtils.MINUTE_IN_MILLIS);

((TextView) view).setText(relTime);

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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