万年历Calendar、js修改日期

//万年历
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE,-1); //改变日期,改变年份、月份类似
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
System.out.println("today is:" + format.format(Calendar.getInstance().getTime()));//格式化现在的时间
System.out.println("yesterday is:" + format.format(cal.getTime()));//格式化改变后的时间
System.out.println(cal.get(Calendar.YEAR));//获得年份
System.out.println(cal.get(Calendar.MONTH));//获得月份
System.out.println(cal.get(Calendar.DATE));//获得日期
System.out.println(cal.get(Calendar.HOUR));//获得小时
System.out.println(cal.get(Calendar.MINUTE));//获得分钟
SimpleDateFormat format1 = new SimpleDateFormat("dd");               
System.out.println("today is:" + format1.format(Calendar.getInstance().getTime()));//格式化现在的时间,获得日期
System.out.println("yesterday is:" + format1.format(cal.getTime()));//格式化改变后的时间,获得日期

//JS
var date = new Date();
console.log(dateToStr(date));  //2015-12-21
date.setFullYear(date.getFullYear()-1);//年份减1年
date.setMonth(date.getMonth()-1);//月份减1月
date.setDate(date.getDate()-1);//日期减1天
date = new Date(date);
console.log(dateToStr(date));//2014-11-20

function dateToStr(date){  //date转成字符串
    var str='';
    var month=date.getMonth()+1;
    str=date.getFullYear()+'-'+(month<=9?('0'+month):month)+'-'+(date.getDate()<=9?('0'+date.getDate()):date.getDate());
    return str;
}
var date = new Date(Date.parse($("#start").val().replace(/-/g, "/")))  //把input标签选择的时间转成date