自定义 java 日期、时间 处理函数集

import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.TimeZone;

public class MyDateUtil {

	public static String TIME_FORMAT = "yyyy-MM-dd HH:mm:ss"; // 注意 HH 和 hh 的区别！
	public static String DATE_FORMAT = "yyyyMMdd";

	// 计算起始日期间隔多少天
	public static String getDayInterval(String st, String ed) {
		SimpleDateFormat myFormatter = new SimpleDateFormat(
				"yyyy-MM-dd HH:mm:ss");
		long day = 0;
		try {
			java.util.Date startDate = myFormatter.parse(st);
			java.util.Date endDate = myFormatter.parse(ed);
			day = (endDate.getTime() - startDate.getTime())
					/ (24 * 60 * 60 * 1000);
		} catch (Exception e) {
			return "";
		}
		return day + "";
	}

	// 判断起始时间差是否在多少分钟内
	public static boolean getMinitueInterval(String st, String ed, int mins) {
		SimpleDateFormat myFormatter = new SimpleDateFormat(
				"yyyy-MM-dd HH:mm:ss");
		boolean inMins = false;
		try {
			java.util.Date startDate = myFormatter.parse(st);
			java.util.Date endDate = myFormatter.parse(ed);
			double minitue = (endDate.getTime() * 1.0 - startDate.getTime())
					/ (60 * 1000);
			System.out.println(minitue);
			if (minitue >= 0 && minitue <= mins) {
				inMins = true;
			} else {
				inMins = false;
			}

		} catch (Exception e) {
			inMins = false;
		}
		return inMins;
	}

	// 指定日期 N 天以前的日期
	public static String getNDaysAgo(String date, int nDaysAgo) {
		Calendar cal1 = Calendar.getInstance();
		Date dateFormat = null;
		try {
			dateFormat = new SimpleDateFormat(DATE_FORMAT).parse(date);
		} catch (ParseException e) {
			e.printStackTrace();
		}
		Long dateLong = dateFormat.getTime(); // 得到的是 long，类似 date
												// -d"2012-11-12 12:00:00" +%s
		cal1.setTime(new java.util.Date(dateLong));
		cal1.add(Calendar.DATE, -nDaysAgo);
		SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd");
		return formatter.format(cal1.getTime());
	}

	// 得到起始范围内的日期列表，包含起始日期，可设置间隔天数
	public static List<String> getDateList(String startDate, String endDate,
			int intervalDay) {
		List<String> listDate = new ArrayList<String>();

		SimpleDateFormat f = new SimpleDateFormat("yyyyMMdd");
		Date dBegin;
		Date dEnd;
		try {
			dBegin = f.parse(startDate);
			dEnd = f.parse(endDate);
			if (dBegin.getTime() <= dEnd.getTime()) {
				for (long i = dBegin.getTime(); i <= dEnd.getTime(); i += 86400000 * (intervalDay + 1)) {
					Date d = new Date(i);
					String date = f.format(d);
					// System.out.println(date);
					listDate.add(date);
				}
			} else {
				for (long i = dBegin.getTime(); i >= dEnd.getTime(); i -= 86400000 * (intervalDay + 1)) {
					Date d = new Date(i);
					String date = f.format(d);
					// System.out.println(date);
					listDate.add(date);
				}
			}
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return listDate;
	}

	// 获取指定日期的前一周（1~7天）时间
	public static List<String> getWeekList(String startDate) {
		List<String> listDate = new ArrayList<String>();

		SimpleDateFormat f = new SimpleDateFormat("yyyyMMdd");
		Date dBegin;
		try {
			dBegin = f.parse(startDate);
			for (long i = 1; i <= 7; i++) {
				Date d = new Date(dBegin.getTime() - 86400000 * i);
				String date = f.format(d);
				// System.out.println(date);
				listDate.add(date);
			}
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return listDate;
	}

	// 将长整型字符串转换为日期字符串，注意：不能带毫秒
	public static String millis2Time(String longStr) {
		long seconds = Long.parseLong(longStr);
		long millis = seconds * 1000;
		Date date = new Date(millis);
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",
				Locale.CHINA);
		sdf.setTimeZone(TimeZone.getTimeZone("GMT+8"));
		String formattedDate = sdf.format(date);
		return formattedDate;
	}

	// 将日期字符串转换为长整型数字，注意：输出不带毫秒
	public static long time2Millis(String date) {
		Date dateFormat = null;
		try {
			dateFormat = new SimpleDateFormat(TIME_FORMAT).parse(date);
		} catch (ParseException e) {
			System.out.println(e.toString());
		}
		Long dateLong = dateFormat.getTime(); // 得到的是 long，类似 date
												// -d"2012-11-12 12:00:00" +%s
		return dateLong;
	}

	// 得到指定日期的星期数，注意：1=星期日 2=星期一 7=星期六，其他类推
	public static String getWeek(String sdate) {
		SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd");
		ParsePosition pos = new ParsePosition(0);
		Date strtodate = formatter.parse(sdate, pos);
		// Date date = strToDate(sdate);
		Calendar c = Calendar.getInstance();
		c.setTime(strtodate);
		// int hour=c.get(Calendar.DAY_OF_WEEK);
		// hour中存的就是星期几了，其范围 1~7
		// 1=星期日 2=星期一 7=星期六，其他类推
		// return new SimpleDateFormat("E").format(c.getTime()); // 返回 星期一
		return String.valueOf(c.get(Calendar.DAY_OF_WEEK));
	}

	// 得到 1 年以前的日期
	public static String getOneYearsAgo(String dateStr) {
		SimpleDateFormat f = new SimpleDateFormat("yyyyMMdd");
		Calendar cal = Calendar.getInstance();
		try {
			cal.setTime(f.parse(dateStr));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		cal.add(Calendar.YEAR, -1);
		Date oneYearsAgo = cal.getTime();
		return f.format(oneYearsAgo);
	}

	// 得到 N 个月以前的日期
	public static String getNMonthsAgo(String dateStr, int n) {
		SimpleDateFormat f = new SimpleDateFormat("yyyyMMdd");
		Calendar cal = Calendar.getInstance();
		try {
			cal.setTime(f.parse(dateStr));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		cal.add(Calendar.MONTH, n);
		Date nMonthsAgo = cal.getTime();
		return f.format(nMonthsAgo);
	}

	// 获得上月最后一天的日期
	public static String getPreMonthEnd(String dateStr) {
		String str = "";
		SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
		Calendar lastDate = Calendar.getInstance();
		try {
			lastDate.setTime(sdf.parse(dateStr));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		lastDate.add(Calendar.MONTH, -1);// 减一个月
		lastDate.set(Calendar.DATE, 1);// 把日期设置为当月第一天
		lastDate.roll(Calendar.DATE, -1);// 日期回滚一天，也就是本月最后一天
		str = sdf.format(lastDate.getTime());
		return str;
	}

	// 获得上月最第一天的日期
	public static String getPreMonthFirst(String dateStr) {
		String str = "";
		SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
		Calendar lastDate = Calendar.getInstance();
		try {
			lastDate.setTime(sdf.parse(dateStr));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		lastDate.set(Calendar.DATE, 1);// 设为当前月的1号
		lastDate.add(Calendar.MONTH, -1);// 减一个月，变为下月的1号
		str = sdf.format(lastDate.getTime());
		return str;
	}

	public static void main(String[] args) {

		// List<String> dateList = getDateList("20130108", "20130107", 0);
		// for (String date : dateList) {
		// System.out.println(date);
		// }

		// List<String> dateList = getWeekList("20121112");
		// for(String date : dateList){
		// System.out.println(date);
		// }

		// System.out.println(millis2Time("1318521600"));

		// System.out.println(time2Millis("2012-12-16 00:05:13")/1000/60);

		// System.out.println(getNDaysAgo("20130114", 1));
		// System.out.println(getNDaysAgo("20130114", 7));

		System.out.println(getWeek("20130122"));

		// System.out.println(getOneYearsAgo("20120227"));

		// System.out.println(getNMonthsAgo("20110827", -6));
		// System.out.println(getNMonthsAgo("20110829", -6));
		// System.out.println(getNMonthsAgo("20120229", -12));

		// System.out.println("20110827".substring(6, 8));

		// System.out.println(getPreMonthFirst("20130430"));

		// System.out.println(getMinitueInterval("2012-12-16 00:05:13",
		// "2012-12-16 00:10:13", 5));
	}
}