js/java 获取当前时间和偏移量

1.首先给出获取当前时间的方法

function dateToString(){
    var now=new Date();
    var year = now.getFullYear();
    var month =(now.getMonth() + 1).toString();
    var day = (now.getDate()).toString();
    var hour = (now.getHours()).toString();
    var minute = (now.getMinutes()).toString();
    var second = (now.getSeconds()).toString();
    if (month.length == 1) {
        month = "0" + month;
    }
    if (day.length == 1) {
        day = "0" + day;
    }
    if (hour.length == 1) {
        hour = "0" + hour;
    }
    if (minute.length == 1) {
        minute = "0" + minute;
    }
    if (second.length == 1) {
        second = "0" + second;
    }
    var dateTime = year + "-" + month + "-" + day +" "+ hour +":"+minute+":"+second;
    return dateTime;
}

返回当前时间字符串：dateTime = "2018-10-12 10:40:57"

 

获取一定偏移量的时间

偏移量是毫秒ms，转化成你要偏移的量的单位即可

以下假设以天为单位获取30天之前的的时间

function dateToString(){
    var now=new Date( new Date() - 1000 * 60 * 60 * 24 * 30);//最后一个30就是偏移量30天
    var year = now.getFullYear();
    var month =(now.getMonth() + 1).toString();
    var day = (now.getDate()).toString();
    var hour = (now.getHours()).toString();
    var minute = (now.getMinutes()).toString();
    var second = (now.getSeconds()).toString();
    if (month.length == 1) {
        month = "0" + month;
    }
    if (day.length == 1) {
        day = "0" + day;
    }
    if (hour.length == 1) {
        hour = "0" + hour;
    }
    if (minute.length == 1) {
        minute = "0" + minute;
    }
    if (second.length == 1) {
        second = "0" + second;
    }
    var dateTime = year + "-" + month + "-" + day +" "+ hour +":"+minute+":"+second;
    return dateTime;
}

结果：

new Date()
　　dateTime = "2018-10-12 10:40:57"

30天之前：
　　dateTime = "2018-09-12 10:40:57"

 

java获取当前时间和偏移量

public static  void main(String args[]){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Date today = new Date();
        String endDate = sdf.format(today);//当前日期
        System.out.println(endDate);

        //获取三十天前日期
        Calendar theCa = Calendar.getInstance();
        theCa.setTime(today);
        theCa.add(theCa.DATE, -30);//最后一个数字30可改，30天的意思
        Date start = theCa.getTime();
        String startDate = sdf.format(start);//三十天之前日期
        System.out.println(startDate);
    }

输出：

2018-10-12
2018-09-12

Process finished with exit code 0