java 日期相关

获取本月第一天

public Date firstDayOfMonth(Date date){Calendar cal = Calendar.getInstance();cal.setTime(date);cal.set(Calendar.DAY_OF_MONTH, 1); return cal.getTime();}

获取本月最后一天

public Date lastDayOfMonth(Date date) {Calendar cal = Calendar.getInstance();cal.setTime(date);cal.set(Calendar.DAY_OF_MONTH, 1);cal.roll(Calendar.DAY_OF_MONTH, -1);return cal.getTime();}public Date lastDayOfMonth2(Date date) {Calendar cal = Calendar.getInstance();cal.setTime(date);int value = cal.getActualMaximum(Calendar.DAY_OF_MONTH);cal.set(Calendar.DAY_OF_MONTH, value);return cal.getTime();}