asp.net C#计算时间--按照日期确定第几周 按照第几周确定日期范围

using System;
using System.Globalization;
namespace ConvertDateTime
{
/// <summary>
/// ConvertDateTime の概要の説明です。

/// </summary>
public class ConvertDate
{
public ConvertDate()
{}
//*******************************************************************//
#region 根据当前日期确定当前是星期几
public static string GetWeekDay(string strDate)
{
try
{
//需要判断的时间
DateTime dTime = Convert.ToDateTime(strDate);

return GetWeekDay(dTime);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}

}
public static string GetWeekDay(DateTime dTime)
{
try
{
//确定星期几
int index = (int)dTime.DayOfWeek;
return GetWeekDay(index);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}

}
#endregion

//*******************************************************************//
#region 获取当前年的最大周数
public static int GetMaxWeekOfYear(int year)
{
try
{
DateTime tempDate = new DateTime(year,12,31);
int tempDayOfWeek = (int)tempDate.DayOfWeek;
if(tempDayOfWeek != 0)
{
tempDate = tempDate.Date.AddDays(-tempDayOfWeek);
}
return GetWeekIndex(tempDate);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}
}
public static int GetMaxWeekOfYear(DateTime dTime)
{
try
{
return GetMaxWeekOfYear(dTime.Year);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}
}
#endregion

//*******************************************************************//
#region 根据时间获取当前是第几周

//如果12月31号与下一年的1月1好在同一个星期则算下一年的第一周
public static int GetWeekIndex(DateTime dTime)
{
try
{
//需要判断的时间
//DateTime dTime = Convert.ToDateTime(strDate);
//确定此时间在一年中的位置
int dayOfYear = dTime.DayOfYear;

//DateTime tempDate = new DateTime(dTime.Year,1,6,calendar);
//当年第一天
DateTime tempDate = new DateTime(dTime.Year,1,1);

//确定当年第一天
int tempDayOfWeek = (int)tempDate.DayOfWeek;
tempDayOfWeek = tempDayOfWeek==0?7:tempDayOfWeek;
//确定星期几
int index = (int)dTime.DayOfWeek;

index = index==0?7:index;

//当前周的范围
DateTime retStartDay = dTime.AddDays(-(index-1));
DateTime retEndDay = dTime.AddDays(7-index);

//确定当前是第几周
int weekIndex = (int)Math.Ceiling(((double)dayOfYear+tempDayOfWeek-1)/7);

if(retStartDay.Year < retEndDay.Year)
{
weekIndex = 1;
}

return weekIndex;
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}
//string retVal = retStartDay.ToString("yyyy/MM/dd") + "～" + retEndDay.ToString("yyyy/MM/dd");

}
public static int GetWeekIndex(string strDate)
{
try
{
//需要判断的时间
DateTime dTime = Convert.ToDateTime(strDate);
return GetWeekIndex(dTime);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}

}
#endregion

//*******************************************************************//
#region 根据时间取周的日期范围

public static string GetWeekRange(string strDate)
{
try
{
//需要判断的时间
DateTime dTime = Convert.ToDateTime(strDate);
return GetWeekRange(dTime);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}
}
public static string GetWeekRange(DateTime dTime)
{
try
{
int index = (int)dTime.DayOfWeek;

index = index==0?7:index;

//当前周的范围
DateTime retStartDay = dTime.AddDays(-(index-1));
DateTime retEndDay = dTime.AddDays(7-index);

return WeekRangeToString(retStartDay,retEndDay);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}

}

public static string GetWeekRange(int year,int weekIndex)
{
try
{
if(weekIndex < 1)
{
throw new Exception("请输入大于0的整数");
}

int allDays = (weekIndex-1)*7;
//确定当年第一天
DateTime firstDate = new DateTime(year,1,1);
int firstDayOfWeek = (int)firstDate.DayOfWeek;

firstDayOfWeek = firstDayOfWeek==0?7:firstDayOfWeek;

//周开始日
int startAddDays = allDays + (1 - firstDayOfWeek);
DateTime weekRangeStart = firstDate.AddDays(startAddDays);
//周结束日
int endAddDays = allDays + (7 - firstDayOfWeek);
DateTime weekRangeEnd = firstDate.AddDays(endAddDays);

if(weekRangeStart.Year > year ||
(weekRangeStart.Year == year && weekRangeEnd.Year > year))
{
throw new Exception("今年没有第"+weekIndex+"周。");
}

return WeekRangeToString(weekRangeStart,weekRangeEnd);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}
}
public static string GetWeekRange(int weekIndex)
{
try
{
return GetWeekRange(DateTime.Now.Year,weekIndex);
}
catch(Exception ex)
{
throw new Exception(ex.Message);
}
}

private static string WeekRangeToString(DateTime weekRangeStart,DateTime weekRangeEnd)
{
string strWeekRangeStart = weekRangeStart.ToString("yyyy/MM/dd");
string strWeekRangeend = weekRangeEnd.AddDays.ToString("yyyy/MM/dd");

return strWeekRangeStart + "～" + strWeekRangeend;

}
#endregion

//*******************************************************************//
#region 转换星期的表示方法

private static string GetWeekDay(int index)
{
string retVal = string.Empty;
switch(index)
{
case 0:
{
retVal = "星期日";
break;
}
case 1:
{
retVal = "星期一";
break;
}
case 2:
{
retVal = "星期二";
break;
}
case 3:
{
retVal = "星期三";
break;
}
case 4:
{
retVal = "星期四";
break;
}
case 5:
{
retVal = "星期五";
break;
}
case 6:
{
retVal = "星期六";
break;
}
}

return retVal;
}
#endregion
}
}