java计算两个年月日之间相差的天数：
public static int daysBetween(String smdate,String bdate) throws ParseException{
int daysInterval=0;
if(StringUtils.isNoneBlank(smdate)&&StringUtils.isNoneBlank(bdate)){
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
Calendar cal = Calendar.getInstance();
cal.setTime(sdf.parse(smdate));
long time1 = cal.getTimeInMillis();
cal.setTime(sdf.parse(bdate));
long time2 = cal.getTimeInMillis();
long between_days=(time2-time1)/(1000*3600*24);
daysInterval = Integer.parseInt(String.valueOf(between_days));
}
return daysInterval;
} java计算年月之间的加法和减法：
public static void main(String[] args) throws ParseException
{
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
String time=sdf.format(new Date());
Calendar cd = Calendar.getInstance();
cd.setTime(sdf.parse(time));
cd.add(Calendar.MONTH, 0);//往前一月，，如果是整数则进行加法，如果是负数，则进行减法
Date date=cd.getTime();
String endTimeString = sdf.format(date);
cd.add(Calendar.MONTH, -7);//往后7个月
String startTimeString = sdf.format(cd.getTime());
String startTime = startTimeString.replaceAll("-", "");//格式日期yyyyMM
String endTime = endTimeString.replaceAll("-", "");//格式日期yyyyMM
System.out.println(startTime);
System.out.println(endTime);
}
获取一个月中的第一天和最后一天：
public static void main(String[] args)
{
// 获取当前年份、月份、日期
Calendar cale = null;
cale = Calendar.getInstance();
// 获取当月第一天和最后一天
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
// 获取前月的第一天
cale = Calendar.getInstance();
cale.add(Calendar.MONTH, -6);
cale.set(Calendar.DAY_OF_MONTH, 1);
String startTimeString = format.format(cale.getTime());
// 获取前月的最后一天
cale = Calendar.getInstance();
cale.add(Calendar.MONTH, 0);
cale.set(Calendar.DAY_OF_MONTH, 0);
String endTimeString = format.format(cale.getTime());
String startTime =startTimeString.replaceAll("-", "");//格式日期yyyyMMdd
String endTime =endTimeString.replaceAll("-", "");//格式日期yyyyMMdd
String layerTime = startTimeString +"至"+endTimeString;
System.out.println(layerTime);
}
计算两个月份之间相差的月份个数：
public int getMonthInterval(String str1,String str2) throws ParseException{
int monthLength = 0;
if(StringUtils.isNoneBlank(str1)&& StringUtils.isNoneBlank(str2)){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
Calendar bef = Calendar.getInstance();
Calendar aft = Calendar.getInstance();
bef.setTime(sdf.parse(str1));
aft.setTime(sdf.parse(str2));
int result = aft.get(Calendar.MONTH) - bef.get(Calendar.MONTH);
int month = (aft.get(Calendar.YEAR) - bef.get(Calendar.YEAR)) * 12;
monthLength = Math.abs(month + result);
}
return monthLength;
}
java对当前月份进行传值计算：
public static Map<String,Object> getMonth(int length) throws ParseException{
Map<String, Object> map = new HashMap<>();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
String time=sdf.format(new Date());
Calendar cd = Calendar.getInstance();
cd.setTime(sdf.parse(time));
cd.add(Calendar.MONTH, -length);//往前一月
Date date=cd.getTime();
String monthFormat= sdf.format(date);
// System.out.println(monthFormat);
String monthString =monthFormat.replaceAll("-", "");//格式日期yyyyMM
map.put("monthFormat", monthFormat);
map.put("monthString", monthString);
return map;
}
