如何在特定时区转换DateTime？ [英] How to convert DateTime in Specific timezone?

问题描述

我很难理解UTC的工作原理。

我必须执行以下操作，但如果我得到正确的结果，我仍然感到困惑。

目标：

1. 确保数据库中的所有保存日期均为UTC格式


2. 更新DefaultTimezone在马尼拉时间


3. 确保所有返回的日期都在马尼拉时间

所以代码是：

  public ConvertDate（DateTime？dateTime）
 {
 if（dateTime！= null）
 {
 Value =（DateTime）dateTime; 
 TimeZone = GetFromConfig.DefaultTimeZone（）; 
} 
 $ 
 
 public ConvertDate（DateTime？dateTime，int GMTTimeZone）
 {
 if（dateTime！= null）
 {
 Value =（DateTime）dateTime; 
 TimeZone = GMTTimeZone; 
} 
} 
 
 
 public int TimeZone 
 {
 get {return m_TimeZone; } 
 set {m_TimeZone = value; } 
} 
 
 
 DateTime m_Value; 
 public DateTime Value 
 {
 get {return m_Value; } 
 set 
 {
 m_Value = value; 
 DateTime converted = m_Value.ToUniversalTime（）。ToLocalTime（）; 
} 
} 
  

样本用法：

  DateTime SampleInputFromUser = new DateTime（2012，1，22）; 
 ConvertDate newConversion = new ConvertDate（SampleInputFromUser，21）; 
 DateTime answer = newConversion.Value; 
  

现在我很困惑'TimeZone'。我不知道如何使用它来实现目标。

希望你明白我的问题，并且有想法来完成目标。

修改

根据@raveturned答案，我得到以下代码：

***在ConvertDate方法中添加

  TimeZoneInfo timeInfo = TimeZoneInfo .FindSystemTimeZoneById（GetFromConfig.ManilaTimeZoneKey（））; 
 ManilaTime = TimeZoneInfo.ConvertTime（dateTime.Value，TimeZoneInfo.Local，timeInfo）.ToUniversalTime（）; 
  

**新属性

  DateTime _ManilaTime; 
 public DateTime ManilaTime 
 {
 get {return _ManilaTime; } 
 set {_ManilaTime = value; 
} 
  

解决方案

有可用于在不同时区之间转换DateTimes的类和方法。看看 TimeZoneInfo 类的ConvertTime方法。

编辑：当您有时间放入数据库时​​，假设它是使用正确的时区信息创建的，您可以轻松转换为UTC：

  DateTime utcTime = inputDateTime.ToUniversalTime（）; 
  

获取timeInfo，在编辑问题中完成：

TimeZoneInfo timeInfo = TimeZoneInfo.FindSystemTimeZoneById（GetFromConfig.ManilaTimeZoneKey（））;

当您将数据库时间发送给用户时，请使用 timeInfo 。

  DateTime userTime = TimeZoneInfo.ConvertTimeFromUtc（dbDateTime，timeInfo）; 
  

个人我会尝试将这个逻辑与适当的get / set方法分开。 >

I find it hard to understand how UTC works.

I have to do the following but I'm still confused if I'd get the right result.

Objectives:

1. Ensure all saved dates in Database are in UTC format
2. Update DefaultTimezone is in Manila time
3. Ensure all returned dates are in Manila Time

So the code is:

public ConvertDate(DateTime? dateTime)
{
    if (dateTime != null)
    {
        Value = (DateTime)dateTime;
        TimeZone = GetFromConfig.DefaultTimeZone(); 
    }
}


public ConvertDate(DateTime? dateTime, int GMTTimeZone)
{
    if (dateTime != null)
    {
        Value = (DateTime)dateTime;
        TimeZone = GMTTimeZone;
    }
}


public int TimeZone
{
    get { return m_TimeZone; }
    set { m_TimeZone = value; }
}


DateTime m_Value;
public DateTime Value
{
    get { return m_Value; }
    set 
    { 
        m_Value = value;
        DateTime converted = m_Value.ToUniversalTime().ToLocalTime();
    }
}

Sample usage:

DateTime SampleInputFromUser = new DateTime(2012, 1, 22);
ConvertDate newConversion = new ConvertDate(SampleInputFromUser, 21);
DateTime answer = newConversion.Value;

Now I get confused for 'TimeZone'. I don't know how to use it to get the objectives.
Hope you understand my question and have the idea to get the objectives done.

Edit

According to @raveturned answer, I get this following code:

***Added in ConvertDate method

TimeZoneInfo timeInfo = TimeZoneInfo.FindSystemTimeZoneById(GetFromConfig.ManilaTimeZoneKey());
ManilaTime = TimeZoneInfo.ConvertTime(dateTime.Value, TimeZoneInfo.Local, timeInfo).ToUniversalTime();

**New Property

DateTime _ManilaTime;
public DateTime ManilaTime
{
    get { return _ManilaTime; }
    set { _ManilaTime = value; }
}

解决方案

The .NET framework already has classes and methods available to convert DateTimes between different time zones. Have a look at the ConvertTime methods of the TimeZoneInfo class.

Edit: When you get the time to put into the database, assuming it was created with correct time zone information you can easily convert to UTC:

DateTime utcTime = inputDateTime.ToUniversalTime();

Get timeInfo as done in the question edit:

TimeZoneInfo timeInfo = TimeZoneInfo.FindSystemTimeZoneById(GetFromConfig.ManilaTimeZoneKey());

When you send the database time to user, convert it to the correct timezone using timeInfo.

DateTime userTime = TimeZoneInfo.ConvertTimeFromUtc(dbDateTime, timeInfo);

Personally I'd try and keep this logic separate from the propery get/set methods.

这篇关于如何在特定时区转换DateTime？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！