var $id = function (id) {
        return "string" == typeof id ? document.getElementById(id) : id;
    };
    var Class = {
        create: function() {
            return function() {
                this.initialize.apply(this, arguments);
            }
        }
    }
    Object.extend = function(destination, source) {
        for (var property in source) {
            destination[property] = source[property];
        }
        return destination;
    }
    var Calendar = Class.create();
    Calendar.prototype = {
        initialize: function(container, options) {
            this.Container = $id(container);//table结构容器
            this.Days = [];//日期列表
            this.SetOptions(options);
            this.Year = this.options.Year;
            this.Month = this.options.Month;
            this.SelectDay = this.options.SelectDay ? new Date(this.options.SelectDay) : null;
            this.onSelectDay = this.options.onSelectDay;
            this.onToday = this.options.onToday;
            this.onFinish = this.options.onFinish;
            this.Draw();
        },
        SetOptions: function(options) {
            this.options = {//默认值
                Year: new Date().getFullYear(),
                Month: new Date().getMonth() + 1,
                SelectDay: null,//选择日期
                onSelectDay: function(){},
                onToday: function(){},
                onFinish: function(){}
            };
            Object.extend(this.options, options || {});
        },
        //上月
        PreMonth: function() {
            //取得上月日期对象
            var d = new Date(this.Year, this.Month - 2, 1);
            //设置属性
            this.Year = d.getFullYear();
            this.Month = d.getMonth() + 1;
            //重绘日历
            this.Draw();
        },
        //下月
            
        NextMonth: function() {
            var d = new Date(this.Year, this.Month, 1);
            this.Year = d.getFullYear();
            this.Month = d.getMonth() + 1;
            this.Draw();
        },
        //上年
        PreYear: function() {
            //取得上月日期对象
            var d = new Date(this.Year, this.Month - 2, 1);
            //设置属性
            this.Year = d.getFullYear()-1;
            //重绘日历
            this.Draw();
        },
        //下年
        NextYear: function() {
            var d = new Date(this.Year, this.Month, 1);
            this.Year = d.getFullYear()+1;
            this.Draw();
        },
        Draw: function() {
            //保存日期列表
            var arr = [];
            //用当月第一天在一周中的日期值作为当月离第一天的天数
            for(var i = 1, firstDay = new Date(this.Year, this.Month - 1, 1).getDay(); i <= firstDay; i++){ arr.push(" "); }
            //用当月最后一天在一个月中的日期值作为当月的天数
            for(var i = 1, monthDay = new Date(this.Year, this.Month, 0).getDate(); i <= monthDay; i++){ arr.push(i); }
            //插入日期
            var frag = document.createDocumentFragment();
            this.Days = [];
            while(arr.length > 0){
                //每个星期插入一个tr
                var row = document.createElement("tr");
                //星期
                for(var i = 1; i <= 7; i++){
                    var cell = document.createElement("td");
                    var a     = document.createElement("a"); 
                    var alink = cell.appendChild(a);
                    alink.innerHTML = " ";
                    if(arr.length > 0){
                        var d = arr.shift();
                        alink.innerHTML = d;
                        if(d > 0){
                            this.Days[d] = alink;
                            
                             var on = new Date(this.Year, this.Month - 1, d); 
                            //判断是否今日