java中如何计算本年上月的开始和结束时间

Posted 2023-05-04

比如 现在时间是 2010年5月17日， 如何计算出 上月的开始和结束日期 ， 也就是 如何计算出 beninDate=2010年3月31日 endDate=2010年5月1日 ？ 

package com.javasky.test2;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class Test6
public static void main(String[] args)
Date nowdate = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Calendar cal = Calendar.getInstance();
/* 设置为当前时间 */
cal.setTime(nowdate);
System.out.println("当前时间是：" + sdf.format(nowdate));
/* 当前日期月份-1 */
cal.add(Calendar.MONTH, -1);
// 得到前一个月的第一天
cal.set(Calendar.DAY_OF_MONTH, cal.getActualMinimum(Calendar.DAY_OF_MONTH));
System.out.println("上个月的第一天是：" + sdf.format(cal.getTime()));
// 得到前一个月的最后一天
cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
System.out.println("上个月的最后一天是：" + sdf.format(cal.getTime()));

参考技术A 用Calendar类比较方便 参考技术B 我没看明白

JS获取本周本季度本月上月的开始日期结束日期

/**
* 获取本周、本季度、本月、上月的开始日期、结束日期
*/
var now = new Date(); //当前日期
var nowDayOfWeek = now.getDay(); //今天本周的第几天
var nowDay = now.getDate(); //当前日
var nowMonth = now.getMonth(); //当前月
var nowYear = now.getYear(); //当前年
nowYear += (nowYear < 2000) ? 1900 : 0; //

var lastMonthDate = new Date(); //上月日期
lastMonthDate.setDate(1);
lastMonthDate.setMonth(lastMonthDate.getMonth()-1);
var lastYear = lastMonthDate.getYear();
var lastMonth = lastMonthDate.getMonth();

//格式化日期：yyyy-MM-dd
function formatDate(date) {
var myyear = date.getFullYear();
var mymonth = date.getMonth()+1;
var myweekday = date.getDate();

if(mymonth < 10){
mymonth = "0" + mymonth;
}
if(myweekday < 10){
myweekday = "0" + myweekday;
}
return (myyear+"-"+mymonth + "-" + myweekday);
}

//获得某月的天数
function getMonthDays(myMonth){
var monthStartDate = new Date(nowYear, myMonth, 1);
var monthEndDate = new Date(nowYear, myMonth + 1, 1);
var days = (monthEndDate - monthStartDate)/(1000 * 60 * 60 * 24);
return days;
}

//获得本季度的开始月份
function getQuarterStartMonth(){
var quarterStartMonth = 0;
if(nowMonth<3){
quarterStartMonth = 0;
}
if(2<nowMonth && nowMonth<6){
quarterStartMonth = 3;
}
if(5<nowMonth && nowMonth<9){
quarterStartMonth = 6;
}
if(nowMonth>8){
quarterStartMonth = 9;
}
return quarterStartMonth;
}

//获得本周的开始日期
function getWeekStartDate() {
var weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek);
return formatDate(weekStartDate);
}

//获得本周的结束日期
function getWeekEndDate() {
var weekEndDate = new Date(nowYear, nowMonth, nowDay + (6 - nowDayOfWeek));
return formatDate(weekEndDate);
}

//获得本月的开始日期
function getMonthStartDate(){
var monthStartDate = new Date(nowYear, nowMonth, 1);
return formatDate(monthStartDate);
}

//获得本月的结束日期
function getMonthEndDate(){
var monthEndDate = new Date(nowYear, nowMonth, getMonthDays(nowMonth));
return formatDate(monthEndDate);
}

//获得上月开始时间
function getLastMonthStartDate(){
var lastMonthStartDate = new Date(nowYear, lastMonth, 1);
return formatDate(lastMonthStartDate);
}

//获得上月结束时间
function getLastMonthEndDate(){
var lastMonthEndDate = new Date(nowYear, lastMonth, getMonthDays(lastMonth));
return formatDate(lastMonthEndDate);
}

//获得本季度的开始日期
function getQuarterStartDate(){

var quarterStartDate = new Date(nowYear, getQuarterStartMonth(), 1);
return formatDate(quarterStartDate);
}

//或的本季度的结束日期
function getQuarterEndDate(){
var quarterEndMonth = getQuarterStartMonth() + 2;
var quarterStartDate = new Date(nowYear, quarterEndMonth, getMonthDays(quarterEndMonth));
return formatDate(quarterStartDate);
}