var ymd = function (id) {   
    return "string" == typeof id ? document.getElementById(id) : id;   
};   
  
function addEventHandler(oTarget, sEventType, fnHandler) {   
    if (oTarget.addEventListener) {   
        oTarget.addEventListener(sEventType, fnHandler, false);   
    } else if (oTarget.attachEvent) {   
        oTarget.attachEvent("on" + sEventType, fnHandler);   
    } else {   
        oTarget["on" + sEventType] = fnHandler;   
    }   
};   
  
var Class = {   
  create: function() {   
    return function() {   
      this.initialize.apply(this, arguments);   
    }   
  }   
}   
  
var Extend = function(destination, source) {   
    for (var property in source) {   
        destination[property] = source[property];   
    }   
    return destination;   
}   
  
var DateSelector = Class.create();   
DateSelector.prototype = {   
  initialize: function(oYear, oMonth, oDay, options) {   
    this.SelYear = ymd(oYear);//年选择对象   
    this.SelMonth = ymd(oMonth);//月选择对象   
    this.SelDay = ymd(oDay);//日选择对象   
       
    this.SetOptions(options);   
       
    var dt = new Date(), iMonth = parseInt(this.options.Month), iDay = parseInt(this.options.Day), iMinYear = parseInt(this.options.MinYear), iMaxYear = parseInt(this.options.MaxYear);   
       
    this.Year = parseInt(this.options.Year) || dt.getFullYear();   
    //this.Year = parseInt(this.options.Year) || dt.getFullYear();   
    this.Month = 1 <= iMonth && iMonth <= 12 ? iMonth : dt.getMonth() + 1;   
    this.Day = iDay > 0 ? iDay : dt.getDate();   
    this.MinYear = iMinYear && iMinYear < this.Year ? iMinYear : this.Year;     
    this.MaxYear = iMaxYear && iMaxYear > this.Year ? iMaxYear : this.Year;   
    this.onChange = this.options.onChange;   
       
    //年设置   
    this.SetSelect(this.SelYear, this.MinYear, this.MaxYear - this.MinYear + 1, this.Year - this.MinYear);   
    //月设置   
    this.SetSelect(this.SelMonth, 1, 12, this.Month - 1);   
    //日设置   
    this.SetDay();   
       
    var oThis = this;   
    //日期改变事件   
    addEventHandler(this.SelYear, "change", function(){   
        oThis.Year = oThis.SelYear.value; oThis.SetDay(); oThis.onChange();   
    });   
    addEventHandler(this.SelMonth, "change", function(){   
        oThis.Month = oThis.SelMonth.value; oThis.SetDay(); oThis.onChange();   
    });   
    addEventHandler(this.SelDay, "change", function(){ oThis.Day = oThis.SelDay.value; oThis.onChange(); });   
  },   
  //设置默认属性   
  SetOptions: function(options) {   
    this.options = {//默认值   
        Year:       2010,//年   
        Month:      0,//月   
        Day:        0,//日   
        MinYear:    2010,//最小年份   
        MaxYear:    2010,//最大年份   
        onChange:   function(){}//日期改变时执行   
    };   
    Extend(this.options, options || {});   
  },   
  //日设置   
  SetDay: function() {   
    //取得月份天数   
    var daysInMonth = new Date(this.Year, this.Month, 0).getDate();   
    if (this.Day > daysInMonth) { this.Day = daysInMonth; };   
    this.SetSelect(this.SelDay, 1, daysInMonth, this.Day - 1);   
  },   
  //select设置   
  SetSelect: function(oSelect, iStart, iLength, iIndex) {   
    //添加option   
    oSelect.options.length = iLength;   
    for (var i = 0; i < iLength; i++) { oSelect.options[i].text = oSelect.options[i].value = iStart + i; }   
    //设置选中项   
    oSelect.selectedIndex = iIndex;   
  }   
};