js实现控制日期月份增减

定义一个当前日期变量

var myDate = new Date();

处理月份添加函数（date当前日期，num增加的月份【正数：增加月份，负数：减少月份】）
function addMonth(date, num) {
num = parseInt(num);
var sDate = dateToDate(date);

var sYear = sDate.getFullYear();
var sMonth = sDate.getMonth() + 1;
var sDay = sDate.getDate();

var eYear = sYear;
var eMonth = sMonth + num;
var eDay = sDay;
while (eMonth > 12) {
eYear++;
eMonth -= 12;
}

var eDate = new Date(eYear, eMonth - 1, eDay);

while (eDate.getMonth() != eMonth - 1) {
eDay--;
eDate = new Date(eYear, eMonth - 1, eDay);
}

return eDate;
};

function dateToDate(date) {
var sDate = new Date();
if (typeof date == 'object'
&& typeof new Date().getMonth == "function"
) {
sDate = date;
}
else if (typeof date == "string") {
var arr = date.split('-')
if (arr.length == 3) {
sDate = new Date(arr[0] + '-' + arr[1] + '-' + arr[2]);
}
}

return sDate;
}；

格式化日期函数

Date.prototype.Format = function(fmt)
{ //author: meizz
var o = {
"M+" : this.getMonth()+1, //月份
"d+" : this.getDate(), //日
"h+" : this.getHours(), //小时
"m+" : this.getMinutes(), //分
"s+" : this.getSeconds(), //秒
"q+" : Math.floor((this.getMonth()+3)/3), //季度
"S" : this.getMilliseconds() //毫秒
};
if(/(y+)/.test(fmt))
fmt=fmt.replace(RegExp.$1, (this.getFullYear()+"").substr(4 - RegExp.$1.length));
for(var k in o)
if(new RegExp("("+ k +")").test(fmt))
fmt = fmt.replace(RegExp.$1, (RegExp.$1.length==1) ? (o[k]) : (("00"+ o[k]).substr((""+ o[k]).length)));
return fmt;
};

//调用函数

var myDate = new Date();
alert(addMonth(myDate, 1).Format("yyyy-MM-dd"));

执行效果

JAVA代码获取日期操作

package test;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.Map;

public class Test {

/**
* @param args
* @throws ParseException
*/
public static void main(String[] args) throws ParseException {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
String str = "2012-05-02";
Date date = df.parse(str);
Map<String, String> map = getFirstday_Lastday_Month(date);
System.out.println("当月第一天：" + getFirstDay());
System.out.println("当月最后一天：" + getLastDay());

System.out.println("一个月前第一天：" + map.get("first"));
System.out.println("一个月前最后一天：" + map.get("last"));
}

/**
* 某一个月第一天和最后一天
* @param date
* @return
*/
private static Map<String, String> getFirstday_Lastday_Month(Date date) {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(Calendar.MONTH, -1);
Date theDate = calendar.getTime();

//上个月第一天
GregorianCalendar gcLast = (GregorianCalendar) Calendar.getInstance();
gcLast.setTime(theDate);
gcLast.set(Calendar.DAY_OF_MONTH, 1);
String day_first = df.format(gcLast.getTime());
StringBuffer str = new StringBuffer().append(day_first).append(" 00:00:00");
day_first = str.toString();

//上个月最后一天
calendar.add(Calendar.MONTH, 1); //加一个月
calendar.set(Calendar.DATE, 1); //设置为该月第一天
calendar.add(Calendar.DATE, -1); //再减一天即为上个月最后一天
String day_last = df.format(calendar.getTime());
StringBuffer endStr = new StringBuffer().append(day_last).append(" 23:59:59");
day_last = endStr.toString();

Map<String, String> map = new HashMap<String, String>();
map.put("first", day_first);
map.put("last", day_last);
return map;
}

/**
* 当月第一天
* @return
*/
private static String getFirstDay() {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
Calendar calendar = Calendar.getInstance();
Date theDate = calendar.getTime();

GregorianCalendar gcLast = (GregorianCalendar) Calendar.getInstance();
gcLast.setTime(theDate);
gcLast.set(Calendar.DAY_OF_MONTH, 1);
String day_first = df.format(gcLast.getTime());
StringBuffer str = new StringBuffer().append(day_first).append(" 00:00:00");
return str.toString();

}

/**
* 当月最后一天
* @return
*/
private static String getLastDay() {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
Calendar calendar = Calendar.getInstance();
Date theDate = calendar.getTime();
String s = df.format(theDate);
StringBuffer str = new StringBuffer().append(s).append(" 23:59:59");
return str.toString();

}

}