java-计算任意日期所在周、月、年的第一天与最后一天

package com.slk.utils;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;/** * 该模块可实现自动计算当前日期对应的周，月，年的第一天与最后一天日期，并且可直接指定当前日期为任意日期。 *  * @author Administrator *  */public class DateTerminator {// 获取当前日期所在周的上下界public final static int CURRENT_WEEK = 0;// 获取当前日期上一周的上下界public final static int LAST_WEEK = 1;// 获取当前日期所在月的上下界public final static int CURRENT_MONTH = 2;// 获取当前日期上一月的上下界public final static int LAST_MONTH = 3;// 获取当前日期所在月的上下界public final static int CURRENT_YEAR = 4;// 获取当前日期上一月的上下界public final static int LAST_YEAR = 5;/** * 根据日期计算所在周的上下界 *  * @param time */public static Map<String, Object> convertWeekByDate(Date time) {Map<String, Object> map = new HashMap<String, Object>();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); // 设置时间格式Calendar cal = Calendar.getInstance();cal.setTime(time);// 判断要计算的日期是否是周日，如果是则减一天计算周六的，否则会出问题，计算到下一周去了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);}System.out.println("要计算日期为:" + sdf.format(cal.getTime())); // 输出要计算日期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String imptimeBegin = sdf.format(cal.getTime());// System.out.println("所在周星期一的日期：" + imptimeBegin);cal.add(Calendar.DATE, 6);String imptimeEnd = sdf.format(cal.getTime());// System.out.println("所在周星期日的日期：" + imptimeEnd);map.put("first", imptimeBegin);map.put("last", imptimeEnd);return map;}/** * 根据日期计算当月的第一天与最后一天 *  * @param time * @return */public static Map<String, Object> convertMonthByDate(Date date) {Map<String, Object> map = new HashMap<String, Object>();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());// 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());map.put("first", day_first);map.put("last", day_last);return map;}/** * 根据日期计算当年的第一天与最后一天 *  * @param time * @return */public static Map<String, Object> convertYearByDate(Date date) {Map<String, Object> map = new HashMap<String, Object>();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");Calendar calendar = Calendar.getInstance();int year = date.getYear() + 1900;calendar.clear();calendar.set(Calendar.YEAR, year);Date currYearFirst = calendar.getTime();calendar.set(Calendar.YEAR, year + 1);calendar.add(calendar.DATE, -1);Date lastYearFirst = calendar.getTime();map.put("first", sdf.format(currYearFirst));map.put("last", sdf.format(lastYearFirst));return map;}/** * 外部调用函数入口############################################################### *  * @param index * @return * @throws ParseException */public static Map<String, Object> getDateTime(int index)throws ParseException {Map<String, Object> map = null;switch (index) {case 0:map = DateTerminator.convertWeekByDate(new Date());break;case 1:Calendar c = Calendar.getInstance();c.add(c.DATE, -7);map = DateTerminator.convertWeekByDate(c.getTime());break;case 2:Calendar c2 = Calendar.getInstance();c2.add(c2.MONTH, 1);map = DateTerminator.convertMonthByDate(c2.getTime());break;case 3:map = DateTerminator.convertMonthByDate(new Date());break;case 4:map = DateTerminator.convertYearByDate(new Date());break;case 5:Calendar c5 = Calendar.getInstance();c5.add(c5.YEAR, -1);map = DateTerminator.convertYearByDate(c5.getTime());break;default:break;}return map;}}

<strong><span style="font-size:32px;">调用：</span></strong>

                Map<String, Object> map = null;//调用getDateTime方法默认时间为当前时间map = DateTerminator.getDateTime(DateTerminator.CURRENT_WEEK);map = DateTerminator.getDateTime(DateTerminator.LAST_WEEK);//map = DateTerminator.getDateTime(DateTerminator.CURRENT_MONTH);//map = DateTerminator.getDateTime(DateTerminator.LAST_MONTH);//map = DateTerminator.getDateTime(DateTerminator.CURRENT_YEAR);//map = DateTerminator.getDateTime(DateTerminator.LAST_YEAR);//输出日期段上下界System.out.println(map.get("first"));System.out.println(map.get("last"));//也可指定任意时间SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");map = DateTerminator.convertMonthByDate(sdf.parse("2015-06-22"));System.out.println(map.get("first"));System.out.println(map.get("last"));