日期选择下拉列表小控件

using System;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

[assembly: TagPrefix("EFPlatform.WebControls", "efp")]
namespace EFPlatform.WebControls
{
[DefaultProperty("Date")]
[ToolboxData("<{0}:DateDropDownList runat=server></{0}:DateDropDownList>")]
public class DateDropDownList : WebControl, INamingContainer
{
#region Properties

#region Data(数据)
#region Date
[Bindable(true)]
[Category("Data")]
[DefaultValue("1900-1-1")]
public DateTime Date
{
get
{
this.GetDate();
return (ViewState["Date"] == null) ? (new DateTime(1900, 1, 1)) : (DateTime)ViewState["Date"];
}

set
{
ViewState["Date"] = value;
}
}
#endregion

#region FirstYear
[Category("Data")]
[DefaultValue(1900)]
public int FirstYear
{
get
{
return (ViewState["FirstYear"] == null) ? 1900 : (int)ViewState["FirstYear"];
}

set
{
ViewState["FirstYear"] = value;
}
}
#endregion

#region LastYear
[Category("Data")]
public int LastYear
{
get
{
return (ViewState["LastYear"] == null) ? DateTime.Now.Year : (int)ViewState["LastYear"];
}

set
{
ViewState["LastYear"] = value;
}
}
#endregion
#endregion

#region Appearance(外观)
#region SelectCssClass
[Category("Appearance")]
public string SelectCssClass
{
get
{
return (ViewState["SelectCssClass"] == null) ? string.Empty : (string)ViewState["SelectCssClass"];
}

set
{
ViewState["SelectCssClass"] = value;
}
}
#endregion

#region YearTitle
[Category("Appearance")]
[DefaultValue("年")]
public string YearTitle
{
get
{
return (ViewState["YearTitle"] == null) ? "年" : (string)ViewState["YearTitle"];
}

set
{
ViewState["YearTitle"] = value;
}
}
#endregion

#region MonthTitle
[Category("Appearance")]
[DefaultValue("月")]
public string MonthTitle
{
get
{
return (ViewState["MonthTitle"] == null) ? "月" : (string)ViewState["MonthTitle"];
}

set
{
ViewState["MonthTitle"] = value;
}
}
#endregion

#region DayTitle
[Category("Appearance")]
[DefaultValue("日")]
public string DayTitle
{
get
{
return (ViewState["DayTitle"] == null) ? "日" : (string)ViewState["DayTitle"];
}

set
{
ViewState["DayTitle"] = value;
}
}
#endregion
#endregion

#endregion

#region GetDate
private void GetDate()
{
if(Page.IsPostBack)
{
string strYear = Page.Request.Form[this.ClientID + "_Year"];
string strMonth = Page.Request.Form[this.ClientID + "_Month"];
string strDay = Page.Request.Form[this.ClientID + "_Day"];
ViewState["Date"] = DateTime.Parse(string.Format("{0}-{1}-{2}", strYear, strMonth, strDay));
}
}
#endregion

#region BuildJScript
private string BuildJScript()
{
StringBuilder sb = new StringBuilder();
sb.Append(" <script language="jscript"> <!-- ");
sb.Append("function {0}_Day_Check() {{ ");
sb.Append("var {0}_obj_Year = document.getElementById("{0}_Year"); ");
sb.Append("var {0}_obj_Month = document.getElementById("{0}_Month"); ");
sb.Append("if(parseInt({0}_obj_Month.value) == 2) {{ ");
sb.Append("if(parseInt({0}_obj_Year.value) % 4 == 0) {{ ");
sb.Append("{0}_Day_SetOptions(29); }} ");
sb.Append("else {{ ");
sb.Append("{0}_Day_SetOptions(28); }} }} ");
sb.Append("else {{ ");
sb.Append("switch(parseInt({0}_obj_Month.value)) {{ ");
sb.Append("case 1: {0}_Day_SetOptions(31); break; ");
sb.Append("case 3: {0}_Day_SetOptions(31); break; ");
sb.Append("case 5: {0}_Day_SetOptions(31); break; ");
sb.Append("case 7: {0}_Day_SetOptions(31); break; ");
sb.Append("case 8: {0}_Day_SetOptions(31); break; ");
sb.Append("case 10: {0}_Day_SetOptions(31); break; ");
sb.Append("case 12: {0}_Day_SetOptions(31); break; ");
sb.Append("case 4: {0}_Day_SetOptions(30); break; ");
sb.Append("case 6: {0}_Day_SetOptions(30); break; ");
sb.Append("case 9: {0}_Day_SetOptions(30); break; ");
sb.Append("case 11: {0}_Day_SetOptions(30); break; ");
sb.Append("default: break; }} }} }} ");
sb.Append(" ");
sb.Append("function {0}_Day_SetOptions({0}_Day_Count) {{ ");
sb.Append("var {0}_obj_Day = document.getElementById("{0}_Day"); ");
sb.Append("var {0}_Day_SelectedDay; ");
sb.Append("if({0}_obj_Day.value == "") {{ ");
sb.Append("{0}_Day_SelectedDay = 1; }} ");
sb.Append("else {{ ");
sb.Append("{0}_Day_SelectedDay = parseInt({0}_obj_Day.value); }} ");
sb.Append("if({0}_Day_SelectedDay > {0}_Day_Count) {{ ");
sb.Append("{0}_Day_SelectedDay = {0}_Day_Count; }} ");
sb.Append("{0}_obj_Day.length = 0; ");
sb.Append("for(var i = 1; i <= {0}_Day_Count; i++) {{ ");
sb.Append("{0}_obj_Day.options.add(new Option(i, i)); }} ");
sb.Append("{0}_obj_Day.value = {0}_Day_SelectedDay; }} ");
sb.Append("--> </script> ");
return string.Format(sb.ToString(), this.ClientID);
}
#endregion

#region BuildHtmlElement
private string BuildHtmlElement()
{
StringBuilder sb = new StringBuilder();
sb.AppendFormat(" <select id="{0}_Year" name="{0}_Year" onchange="{0}_Day_Check();" class="{1}">", this.ClientID, this.SelectCssClass);

for(int i = this.FirstYear; i <= this.LastYear; i++)
{
if(i == this.Date.Year)
{
sb.AppendFormat(" <option value="{0}" selected>{0}</option>", i);
}
else
{
sb.AppendFormat(" <option value="{0}">{0}</option>", i);
}
}

sb.AppendFormat(" </select> {1}<select id="{0}_Month" name="{0}_Month" onchange="{0}_Day_Check();" class="{2}">", this.ClientID, this.YearTitle, this.SelectCssClass);

for(int i = 1; i <= 12; i++)
{
if(i == this.Date.Month)
{
sb.AppendFormat(" <option value="{0}" selected>{0}</option>", i);
}
else
{
sb.AppendFormat(" <option value="{0}">{0}</option>", i);
}
}

sb.AppendFormat(" </select>{1}<select id="{0}_Day" name="{0}_Day" onmouseover="{0}_Day_Check();" class="{2}">", this.ClientID, this.MonthTitle, this.SelectCssClass);

for(int i = 1; i <= DateTime.DaysInMonth(this.Date.Year, this.Date.Month); i++)
{
if(i == this.Date.Day)
{
sb.AppendFormat(" <option value="{0}" selected>{0}</option>", i);
}
else
{
sb.AppendFormat(" <option value="{0}">{0}</option>", i);
}
}

sb.AppendFormat(" </select>{0} ", this.DayTitle);
return sb.ToString();
}
#endregion

#region override RenderChildren
protected override void RenderChildren(HtmlTextWriter writer)
{
writer.Write(this.BuildJScript());
writer.Write(this.BuildHtmlElement());
base.RenderChildren(writer);
}
#endregion
}
}