Ｊａｖａ　日期加减　该当日期是所在月的第几周　所在月的最后一天

/**

* 根据日期，取得星期几

*

* @param date

* @return

*/

private String getWeek(Date date) {

SimpleDateFormat sdf = new SimpleDateFormat("EEEE");

String week = sdf.format(date);

return week.substring(0, 1);

}

@SuppressWarnings("unused")

private String getWeek(String date) throws ParseException {

SimpleDateFormat sdf = new SimpleDateFormat("EEEE");

String week = sdf.format(stringToDate(date));

return week.substring(0, 1);

}

/**

* 日期的天数的加减

*

* @param date

* @param con

* @return

* @throws ParseException

*/

@SuppressWarnings("unused")

private String getDateTO(String date, int count) throws ParseException {

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

SimpleDateFormat sdf = new SimpleDateFormat("EEEE");

String week = sdf.format(stringToDate(date));

Calendar rightNow = Calendar.getInstance();

rightNow.setTime(stringToDate(date));

rightNow.add(Calendar.DATE, count);

Date dt1 = rightNow.getTime();

String str = dateFormat.format(dt1).replaceAll("-", "");

return str;

}

/**

* String类型变为DATE类型

*

* @param dateStr

* @param con

* @return

* @throws ParseException

*/

@SuppressWarnings("unused")

private Date stringToDate(String dateStr) throws ParseException {

String dateString = "0000-00-00";

if (!"".equals(dateStr) && dateStr != null) {

if (dateStr.contains("-")) {

dateString = dateStr;

} else {

dateString = dateStr.substring(0, 4) + "-"

+ dateStr.substring(4, 6) + "-"

+ dateStr.substring(6, 8);

}

}

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

return dateFormat.parse(dateString);

}

/**

* 取得一个月的第一天

*

* @param someDate

* @return

*/

@SuppressWarnings("unused")

private String getMonthFirstDay(Date someDate) {

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

String getMonthFirstDay = "";

Calendar ca = Calendar.getInstance();

ca.setTime(someDate);

ca.set(Calendar.DAY_OF_MONTH, 1);

// 一日目

Date firstDate = ca.getTime();

getMonthFirstDay = dateFormat.format(firstDate);

return getMonthFirstDay;

}

/**

* 取得一个月的最后一天

*

* @param someDate

* @return

*/

@SuppressWarnings("unused")

private String getMonthLastDay(Date someDate) {

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

String getMonthLastDay = "";

Calendar ca = Calendar.getInstance();

ca.setTime(someDate);

ca.add(Calendar.MONTH, 1);

ca.add(Calendar.DATE, -1);

// 最後日

getMonthLastDay = dateFormat.format(ca.getTime());

return getMonthLastDay;

}

/**取得一个日期是所在月的第几周

*

* @param str

* @return

* @throws Exception

*/

private int getWeekNum(String str) throws Exception {

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

Date date = sdf.parse(str);

Calendar calendar = Calendar.getInstance();

calendar.setTime(date);

int week = calendar.get(Calendar.WEEK_OF_MONTH);

int day = calendar.get(Calendar.DAY_OF_WEEK);

return week;

}