检测当前是否启用了DST

Question

我需要找到一种简单的方法来了解本地机器的"自动调整夏令时时钟"选项是否已启用。如果该选项打开，我需要知道它当前是否已应用（即系统中当前是否为DST）。提前感谢

Answer 1

您可以找到当前系统默认时区，以及它当前是否使用夏令时（夏令时），如下所示（.NET 3.5以后版本）：

TimeZoneInfo zone = TimeZoneInfo.Local;
if (zone.SupportsDaylightSavingTime)
{
    Console.WriteLine("System default zone uses DST...");
    Console.WriteLine("In DST? {0}", zone.IsDaylightSavingTime(DateTime.UtcNow));       
}
else
{
    Console.WriteLine("System default zone does not use DST.");
}

Answer 2

另一个选项可能是DateTime.IsDaylightSavingTime方法。查看MSDN。

if (DateTime.Now.IsDaylightSavingTime())
    Console.WriteLine("Daylight Saving");
else
    Console.WriteLine("No Daylight Saving");

Answer 3

您可以读取注册表以确定是否选中了复选框。读取此密钥，

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformationDynamicDaylightTimeDisabled

=0或1（禁用）

所以类似于：

    Dim retval As Object = Microsoft.Win32.Registry.GetValue("HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlTimeZoneInformation", "DynamicDaylightTimeDisabled", 0)
    If retval IsNot Nothing Then
        Select Case CInt(retval)
            Case 0
                Trace.WriteLine("Automatically adjust clock for Daylight Saving Time is checked")
            Case 1
                Trace.WriteLine("Automatically adjust clock for Daylight Saving Time is NOT checked")
        End Select
    End If

Answer 4

下面是C#中的另一个例子

private static bool IsDayLightSavingsEnabled()
{
  try
  {
    var result = Registry.GetValue(@"HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlTimeZoneInformation", "DynamicDaylightTimeDisabled", 1);
    return !Convert.ToBoolean(result); //0 - Checked/enabled,  1 - Unchecked/disabled
  }
  catch
  { }
  return false;
}