java的calendar类常见日期处理

/**
* 得到当前月的上一个月，返回2016-06这样的字符串
*/
public static String getLastMonth() {
Calendar cal = Calendar.getInstance();
cal.add(Calendar.MONTH, -1);
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM");
String date = format.format(cal.getTime());
return date;
}

/**
* 得到当前月的第一天，返回2016-06-01这样的字符串
*
* @return
*/
public static String getCurrentMonthFirstDay() {
Calendar c = Calendar.getInstance();
c.add(Calendar.MONTH, 0);
c.set(Calendar.DAY_OF_MONTH, 1);// 设置为1号,当前日期既为本月第一天
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
String first = format.format(c.getTime());
return first;
}

public static String getCurrentMonthTheLastDay() {
Calendar c = Calendar.getInstance();
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));
return dateToStr(c.getTime(), "yyyy-MM-dd");
}

/**
* 获取当前年的第一个月，返回2016-01这样的数据
*
* @return
*/
public static String getCurrentYearFirstMonth() {
Calendar c = Calendar.getInstance();
c.add(Calendar.YEAR, 0);
c.set(Calendar.DAY_OF_YEAR, 1);
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM");
String first = format.format(c.getTime());
return first;
}

/**
* 获取当前年已过的所有季度的集合(季度包含的月份未完则也算入)<String>
*/
public static List<String> getAllQuarterOfThisYear() {
List<String> quarters = new ArrayList<String>();
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH) + 1;
if (month > 9) {
quarters.add(year + "-" + 1);
quarters.add(year + "-" + 2);
quarters.add(year + "-" + 3);
quarters.add(year + "-" + 4);
return quarters;
}
if (month > 6 && month <= 9) {
quarters.add(year + "-" + 1);
quarters.add(year + "-" + 2);
quarters.add(year + "-" + 3);
return quarters;
}
if (month > 3 && month <= 6) {
quarters.add(year + "-" + 1);
quarters.add(year + "-" + 2);
return quarters;
}
if (month >= 1 && month <= 3) {
quarters.add(year + "-" + 1);
return quarters;
}
return null;
}

/**
* 获取昨天
*
* @return
*/
public static String getYesterDay() {
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
String yesterday = new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime());
return yesterday;
}

/**
* 获取指定时间范围内的所有日期
*
* @param startDate
*            (format="2016-06-01")
* @param endDate
*            (format="2016-07-12")
* @return
* @throws ParseException
*/
public static List<String> getDaysBetween(String startDate, String endDate) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
List<String> result = new ArrayList<String>();
result.add(startDate);
try {
Calendar calBegin = Calendar.getInstance();
// 使用给定的 Date 设置此 Calendar 的时间
Date begin = format.parse(startDate);
calBegin.setTime(begin);
Calendar calEnd = Calendar.getInstance();
// 使用给定的 Date 设置此 Calendar 的时间
Date end = format.parse(endDate);
calEnd.setTime(end);
// 测试此日期是否在指定日期之后
while (end.after(calBegin.getTime())) {
// 根据日历的规则，为给定的日历字段添加或减去指定的时间量
calBegin.add(Calendar.DAY_OF_MONTH, 1);
result.add(format.format(calBegin.getTime()));
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}

/**
* 获取指定时间范围内的所有月份
*
* @param startDate(format="2016-06")
* @param endDate(format="2016-08")
* @return
* @throws ParseException
*/
public static List<String> getMonthsBetween(String startDate, String endDate) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");
List<String> result = new ArrayList<String>();
try {
Calendar calBegin = Calendar.getInstance();
Calendar calEnd = Calendar.getInstance();
calBegin.setTime(sdf.parse(startDate));
calBegin.set(calBegin.get(Calendar.YEAR), calBegin.get(Calendar.MONTH), 1);
calEnd.setTime(sdf.parse(endDate));
calEnd.set(calEnd.get(Calendar.YEAR), calEnd.get(Calendar.MONTH), 2);
Calendar curr = calBegin;
while (curr.before(calEnd)) {
result.add(sdf.format(curr.getTime()));
curr.add(Calendar.MONTH, 1);
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}

/**
* 获取指定日期范围的所有周的周一~周日，格式为周一~周日，如2016-09-19为周一，2016-09-25为周天，返回结果为[2016-09-19
* ~2016-09-25]
*
* @param startDate
*            起始时间(2016-09-19)
* @param endDate
*            结束时间(2016-09-25)
* @return
* @throws ParseException
*/
public static List<String> getWeeksBetween(String startDate, String endDate) {
// startDate不能大于endDate
List<String> result = new ArrayList<String>();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); // 设置时间格式
try {
Calendar calBegin = Calendar.getInstance();
// 使用给定的 Date 设置此 Calendar 的时间
Date begin = sdf.parse(startDate);
calBegin.setTime(begin);
int dayWeek = calBegin.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
if (1 == dayWeek) {
calBegin.add(Calendar.DAY_OF_MONTH, -1);
}
calBegin.setFirstDayOfWeek(Calendar.MONDAY);// 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
Calendar calEnd = Calendar.getInstance();
// 使用给定的 Date 设置此 Calendar 的时间
Date end = sdf.parse(endDate);
calEnd.setTime(end);
// 测试此日期是否在指定日期之后
while (end.after(calBegin.getTime())) {
// 根据日历的规则，为给定的日历字段添加或减去指定的时间量
calBegin.add(Calendar.DAY_OF_MONTH, 1);
int day = calBegin.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
calBegin.add(Calendar.DATE, calBegin.getFirstDayOfWeek() - day);// 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
// 获取周一
String monday = sdf.format(calBegin.getTime());
calBegin.add(Calendar.DATE, 6);
// 获取周日
String sunday = sdf.format(calBegin.getTime());
result.add(monday + "~" + sunday);
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}

/**
* 获取当前日期的前index天(以当前日期开始计算) index = -6表示当天日期的前7天 index = -29表示当前日期的前30天
*
* @return
*/
public static String getLastIndexDayStr(int index) {
Date now = new Date();
Calendar c = Calendar.getInstance();
c.setTime(now);
c.add(Calendar.DAY_OF_MONTH, index);
return dateToStr(c.getTime(), "yyyy-MM-dd");
}

/**
* 获取当天
*/
public static String getTodayStr() {
Date now = new Date();
return dateToStr(now, "yyyy-MM-dd");
}

/**
* 获取最近3个月开始日期(包含当前月所有月)
*
* @return
*/
public static String getLast3MonthsStartDateStr() {
Date now = new Date();
Calendar c = Calendar.getInstance();
c.setTime(now);
c.add(Calendar.MONTH, -2);
return dateToStr(c.getTime(), "yyyy-MM") + "-01";
}

/**
* 获取星期几
* @param dateStr
* @return
*/
public static String getWeekNameOfDate(String dateStr) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
Calendar c = Calendar.getInstance();
try {
c.setTime(format.parse(dateStr));
} catch (ParseException e) {
e.printStackTrace();
}
int dayForWeek = 0;
if (c.get(Calendar.DAY_OF_WEEK) == 1) {
dayForWeek = 7;
} else {
dayForWeek = c.get(Calendar.DAY_OF_WEEK) - 1;
}
String result = "";
switch (dayForWeek) {
case 1:
result = "星期一";
break;
case 2:
result = "星期二";
break;
case 3:
result = "星期三";
break;
case 4:
result = "星期四";
break;
case 5:
result = "星期五";
break;
case 6:
result = "星期六";
break;
case 7:
result = "星期天";
break;
}
return result;
}

/**
* 获取指定日期所在月的第一天
*
* @param date
* @return yyyy-MM-dd
*/
public static String getMonthStartDate(String date) {
try {
Calendar calendar = Calendar.getInstance();
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
calendar.setTime(format.parse(date));
calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
return format.format(calendar.getTime());
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}

/**
* 获取指定日期所在月的最后一天
*
* @param date
* @return yyyy--MM-dd
*/
public static String getMonthEndDate(String date) {
try {
Calendar calendar = Calendar.getInstance();
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
calendar.setTime(format.parse(date));
calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
return format.format(calendar.getTime());
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}

/**
* 获取指定日期所在周的周一
* @param date
* @return yyyy-MM-dd
*/
public static String getMondayOfDate(String date) {
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); // 设置时间格式
Calendar cal = Calendar.getInstance();
cal.setTime(sdf.parse(date));
int dayWeek = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
if (1 == dayWeek) {
cal.add(Calendar.DAY_OF_MONTH, -1);
}
cal.setFirstDayOfWeek(Calendar.MONDAY);// 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
int day = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
return sdf.format(cal.getTime());
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}

/**
* 获取指定日期所在周的周日
* @param date
* @return yyyy-MM-dd
*/
public static String getSundayOfDate(String date) {
try {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); // 设置时间格式
Calendar cal = Calendar.getInstance();
cal.setTime(sdf.parse(date));
int dayWeek = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
if (1 == dayWeek) {
cal.add(Calendar.DAY_OF_MONTH, -1);
}
cal.setFirstDayOfWeek(Calendar.MONDAY);// 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
int day = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
cal.add(Calendar.DATE, cal.getFirstDayOfWeek()-day);//根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
cal.add(Calendar.DATE, 6);
return sdf.format(cal.getTime());
} catch (ParseException e) {
e.printStackTrace();
}
return null;
}

**
* 获取月末到当前时间的秒数
*/
public static long getSecondsBetweenEndMothToNow() {
Calendar c = Calendar.getInstance();
c = Calendar.getInstance();  
        c.add(Calendar.MONTH, 1);  
        c.set(Calendar.DAY_OF_MONTH, 0);
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); 
        String lastday = format.format(c.getTime());
        lastday = lastday + " 23:59:59";
        Date last = null;
        long sec = 0;
try {
last = format.parse(lastday);
long diff = last.getTime() - System.currentTimeMillis();
sec = diff / 1000;
} catch (ParseException e) {
e.printStackTrace();
}
return sec;
}